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Articles 3151 - 3180 of 11124

Full-Text Articles in Engineering

Scheduling Allocation And Inventory Replenishment Problems Under Uncertainty: Applications In Managing Electric Vehicle And Drone Battery Swap Stations, Amin Asadi Jul 2021

Scheduling Allocation And Inventory Replenishment Problems Under Uncertainty: Applications In Managing Electric Vehicle And Drone Battery Swap Stations, Amin Asadi

Graduate Theses and Dissertations

In this dissertation, motivated by electric vehicle (EV) and drone application growth, we propose novel optimization problems and solution techniques for managing the operations at EV and drone battery swap stations. In Chapter 2, we introduce a novel class of stochastic scheduling allocation and inventory replenishment problems (SAIRP), which determines the recharging, discharging, and replacement decisions at a swap station over time to maximize the expected total profit. We use Markov Decision Process (MDP) to model SAIRPs facing uncertain demands, varying costs, and battery degradation. Considering battery degradation is crucial as it relaxes the assumption that charging/discharging batteries do not …


Modernization Of Scienttific Mathematics Formula In Technology, Iwasan D. Kejawa Ed.D, Prof. Iwasan D. Kejawa Ed.D Jul 2021

Modernization Of Scienttific Mathematics Formula In Technology, Iwasan D. Kejawa Ed.D, Prof. Iwasan D. Kejawa Ed.D

Department of Mathematics: Faculty Publications

Abstract
Is it true that we solve problem using techniques in form of formula? Mathematical formulas can be derived through thinking of a problem or situation. Research has shown that we can create formulas by applying theoretical, technical, and applied knowledge. The knowledge derives from brainstorming and actual experience can be represented by formulas. It is intended that this research article is geared by an audience of average knowledge level of solving mathematics and scientific intricacies. This work details an introductory level of simple, at times complex problems in a mathematical epidermis and computability and solvability in a Computer Science. …


Europa Environmental Testing Of Thermal Hardware For The Mapping Imaging Spectrometer For Europa (Mise) Instrument, Ian M. Mckinley, Jose I. Rodriguez, Mason Mok, Kristen S. Maynard, Curtis Bingham, Andrew Ostler, Patrick Strong Jul 2021

Europa Environmental Testing Of Thermal Hardware For The Mapping Imaging Spectrometer For Europa (Mise) Instrument, Ian M. Mckinley, Jose I. Rodriguez, Mason Mok, Kristen S. Maynard, Curtis Bingham, Andrew Ostler, Patrick Strong

Space Dynamics Laboratory Publications

The Europa Clipper spacecraft, scheduled for launch in June 2022, hosts a suite of instruments including the Mapping Imaging Spectrometer for Europa (MISE). MISE is a high-optical through-put push-broom infrared imaging spectrometer that can collect measurements within Europa’s challenging radiation environment. It is externally mounted to the spacecraft and as a result is exposed to high radiation levels and cold temperatures. The instrument consists of a scan mirror assembly, an optical bench including a Dyson spectrometer and a telescope, and a structure that supports a cryocooler and a radiator. The cryocooler is used to actively cool the focal plane array …


Scaling Flight Test Data Between A Scaled Aircraft And A Cessna 172 For Use In Trajectory Energy Model Validation, Cody William Nettleton Jul 2021

Scaling Flight Test Data Between A Scaled Aircraft And A Cessna 172 For Use In Trajectory Energy Model Validation, Cody William Nettleton

Theses and Dissertations

Currently in the general aviation sector, a new type of aircraft is rising to prominence. It is known as Urban Air Mobility (UAM) and takes many shapes and sizes. The goal of UAM is to produce aircraft that can be used to travel into and out of the city in an efficient manner through the sky. This may cut down on many people’s commutes and lower the amount of ground traffic in cities. One core component of UAM research is to determine the fuel consumption during phases of flight such as conventional takeoff and landing, as well as cruise travel …


The Importance Of Strategic Communication For Building Employee Resource Groups In Aviation, Lynnette Darnell Jul 2021

The Importance Of Strategic Communication For Building Employee Resource Groups In Aviation, Lynnette Darnell

Doctoral Dissertations and Projects

In this qualitative case study, the research explores the importance of strategic communication for building employee resource groups in aviation, specifically at a regional airline. To expand and develop knowledge regarding employee resource groups, the researcher looks at a widely distributed workforce to understand how the lack of strategically planned communication can impact employee resource group development and employee engagement. The data were collected through semi-structured interviews and a focus group of the employee resource group members, which provided insight on their experience engaging with the employee resource groups, preferred communication methods and tools, and their perception of leadership involvement. …


Additively Manufactured Dielectric Elastomer Actuators: Development And Performance Enhancement, Stanislav Sikulskyi Jul 2021

Additively Manufactured Dielectric Elastomer Actuators: Development And Performance Enhancement, Stanislav Sikulskyi

Doctoral Dissertations and Master's Theses

The recently emerging and actively growing areas of soft robotics and morphing structures promise endless opportunities in a wide range of engineering fields, including biomedical, industrial, and aerospace. Soft actuators and sensors are essential components of any soft robot or morphing structure. Among the utilized materials, dielectric elastomers (DEs) are intrinsically compliant, high energy density polymers with fast and reversible electromechanical response. Additionally, the electrically driven work principle allows DEs to be distributed in a desired fashion and function locally with minimum interference. Thus, a great effort is being made towards utilizing additive manufacturing (AM) technologies to fully realize the …


Reduced Sample Minimum Strength Estimates For Novel Material Systems: Effects On Confidence And Structural Risk, Andrew Carl Ollikainen Jul 2021

Reduced Sample Minimum Strength Estimates For Novel Material Systems: Effects On Confidence And Structural Risk, Andrew Carl Ollikainen

Theses and Dissertations

There are ongoing efforts to standardize the materials, methods and process controls used in additive manufacturing. To support the broader use of additive manufacturing (AM) in the aerospace industry, the statistics working group of the Composite Materials Handbook (CMH-17) is evaluating whether its current methods of calculating minimum strength values are suitable for these new materials. The work presented in this dissertation investigates methods for determining minimum strength estimates in a way that will benefit application of AM materials in engineering practice. The greatest challenge in conducting such an assessment is accounting for the many variables in material, processing, and …


Monte-Carlo-Based Analysis Of Traffic Flow For Urban Air Mobility Vehicles, Sara Ghayouraneh Jul 2021

Monte-Carlo-Based Analysis Of Traffic Flow For Urban Air Mobility Vehicles, Sara Ghayouraneh

Graduate Theses and Dissertations

The research conducted in this dissertation is focused on developing a simulation tool that can predict the traffic flow patterns of the Urban Air Mobility vehicles to alleviate some of the challenges related to their traffic management. First, an introduction to the concept of Urban Air Mobility is given, the usage of Automatic Dependent Surveillance-Broadcast systems for Urban Air Mobility vehicles is suggested and dynamic addressing concept is introduced as an answer to a part of air traffic management and address scarcity challenge for Urban air Mobility vehicles. Next, in order to simulate the traffic flow patterns of the Urban …


Development And Applications Of Adjoint-Based Aerodynamic And Aeroacoustic Multidisciplinary Optimization For Rotorcraft, Ramiz Omur Icke Jul 2021

Development And Applications Of Adjoint-Based Aerodynamic And Aeroacoustic Multidisciplinary Optimization For Rotorcraft, Ramiz Omur Icke

Mechanical & Aerospace Engineering Theses & Dissertations

Urban Air Mobility (UAM) is one of the most popular proposed solutions for alleviating traffic problems in populated areas. In this context, the proposed types of vehicles mainly consist of rotors and propellers powered by electric motors. However, those rotary-wing components can contribute excessively to noise generation. Therefore, a significant noise concern emerges due to urban air vehicles in or around residential areas. Reducing noise emitted by air vehicles is critically important to improve public acceptance of such vehicles for operations in densely populated areas.

Two main objectives of the present dissertation are: (1) to expand the multidisciplinary optimization to …


A Digital One Degree Of Freedom Model Of An Electromagnetic Position Sensor, Michelle Elizabeth Weinmann Jul 2021

A Digital One Degree Of Freedom Model Of An Electromagnetic Position Sensor, Michelle Elizabeth Weinmann

Mechanical & Aerospace Engineering Theses & Dissertations

The purpose of this project was to improve an existing system currently in use by NASA Langley Research Center (LaRC). The 6-inch Magnetic Suspension and Balance System (MSBS) built at MIT is operational with control in three degrees of freedom, with two additional degrees of freedom exhibiting passive stability. The means for measuring model displacement within the magnetic environment is an Electromagnetic Position Sensor (EPS), consisting of excitation coils at 20 kHz and multiple sets of pickup coils. The pickup coil voltages are proportional to model displacement in each degree of freedom. However, the EPS electronic signal processing system is …


Issue 7: Contributors, David Hartshorn, Martin Jarrold Jun 2021

Issue 7: Contributors, David Hartshorn, Martin Jarrold

Online Journal of Space Communication

List of Issue 7 Contributors.


Future Solutions: Access To Ict: A Tale Of Three Briefings, David Hartshorn Jun 2021

Future Solutions: Access To Ict: A Tale Of Three Briefings, David Hartshorn

Online Journal of Space Communication

If your inbox is anything like mine, then you already know that the publication of satellite communications reports has become an industry unto itself. But that's not to say that it's always an end unto itself. On the contrary.


Future Solutions: Universal Access, David Hartshorn Jun 2021

Future Solutions: Universal Access, David Hartshorn

Online Journal of Space Communication

Today, the nations of the world have an immediate opportunity to advance essential telecommunication policy objectives through harmonisation of regulations governing the use of fixed satellite-based network solutions.


Regulatory Reform: Strengthening Access To Information & Communications Technologies: Guidelines To Facilitate Policy & Regulation For Satellite Services, Global Vsat Forum Jun 2021

Regulatory Reform: Strengthening Access To Information & Communications Technologies: Guidelines To Facilitate Policy & Regulation For Satellite Services, Global Vsat Forum

Online Journal of Space Communication

This document was prepared by GVF, an association of organisations engaged in the delivery of advanced broadband and narrowband satellite services to consumers, and commercial and government enterprises worldwide.


Regulatory Reform: In The Land Of The 'Coffeenet', Martin Jarrold Jun 2021

Regulatory Reform: In The Land Of The 'Coffeenet', Martin Jarrold

Online Journal of Space Communication

Sitting down to write this article at a desk some 30 miles south of central London, and less than one degree west of the Greenwich meridian, I became immediately more conscious than usual of geography. The frequently interwoven use of such western-centric cartographic labels as Middle East, and Far East, with the geographically more precise terms of Western or Central Asia, and East and South-East Asia, sometimes causes us to confuse the actual proximity of Europe's, much larger, near-neighbour.


Regulatory Reform: Asia's Great Step Forward, David Hartshorn Jun 2021

Regulatory Reform: Asia's Great Step Forward, David Hartshorn

Online Journal of Space Communication

This paper was presented at Connect-World Asia Pacific, June 2002.

Forget about a great leap forward. All that's needed to facilitate communications in Asia are a few small steps. Indeed, today all nations of the world have an immediate opportunity to advance essential telecommunication policy objectives through harmonisation of regulations governing the use of telecommunications solutions.


Regulatory Reform: Wanted: A Bridge For Africa's Digital Divide Apply: Pretty Much Anywhere In Africa Quote Reference: Vsat, Martin Jarrold Jun 2021

Regulatory Reform: Wanted: A Bridge For Africa's Digital Divide Apply: Pretty Much Anywhere In Africa Quote Reference: Vsat, Martin Jarrold

Online Journal of Space Communication

For Africa, and for the economy of the whole planet, those hundreds of millions of people across the continent who are currently denied reasonable access to even simple voice service represent a vast untapped pool of creativity. This very large and potentially very powerful economic dynamo demands access to more than the simplest tools of communication, and requires the means to unleash the potential productivity of its own knowledge-base into an increasingly connected world. The International Telecommunications Union acknowledges this, as does its sister organisation, the United Nations. The Global VSAT Forum enjoins you to acknowledge it too.


Overview: A+B+C = Vsat, Martin Jarrold Jun 2021

Overview: A+B+C = Vsat, Martin Jarrold

Online Journal of Space Communication

The benefits of VSAT systems and services are being realised in all spheres across the globe, both private and public. Banks, government departments, schools, hospitals, home offices, small enterprises, multi-national corporates, and rural telephony… all sectors are seizing upon the opportunity to get connected through satellite communications.


Overview: Satellite Communication In Ghana - Challenges And Prospects, Kwasi Boateng Jun 2021

Overview: Satellite Communication In Ghana - Challenges And Prospects, Kwasi Boateng

Online Journal of Space Communication

Busy Internet is a Ghanaian ISP that uses satellite connectivity to bring Internet to West Africans. The operations of this ISP illustrate the reliability, versatility and efficiency of, VSAT, (Very Small Aperture Terminal) networks in delivering fast broadband Internet services.


Overview: The View From 22,300 Miles High, David Hartshorn Jun 2021

Overview: The View From 22,300 Miles High, David Hartshorn

Online Journal of Space Communication

Asia's geography, claiming many of the world's highest peaks, has provided a dramatic setting for a climbing expedition that began decades ago, when the satellite communications community took its first step on the lower slopes of the mountain.


Overview: Politics And Technology Converge: Case Studies On The Effects Of Regulatory Reform On Vsat Adoption In Developing Countries, Emmanuel Adugu, Kwasi Boateng, D. Flournoy, Eric Gavua, Wencelous Kaswoswe, Miao Zhang Jun 2021

Overview: Politics And Technology Converge: Case Studies On The Effects Of Regulatory Reform On Vsat Adoption In Developing Countries, Emmanuel Adugu, Kwasi Boateng, D. Flournoy, Eric Gavua, Wencelous Kaswoswe, Miao Zhang

Online Journal of Space Communication

Developing countries are actively implementing satellite data networks, and have undertaken policy reforms to facilitate such networks. This research examines how regulatory changes have resulted in the removal of barriers relating to the deployment of access technologies and growth in connectivity, especially in VSAT installations for low cost Internet access. In addition, this research seeks to identify the socio-economic impact of emerging data network applications in government, business, health and education. In some cases, government offices have been the driver of change; in other cases, businesses have been the ones to initiate and press these developments forward.


Overview: Pipelines Of The Skies, Errol Olivier Jun 2021

Overview: Pipelines Of The Skies, Errol Olivier

Online Journal of Space Communication

Advances in fixed satellite technology are enabling oil and gas concerns to enhance the efficiency of offshore operations with cost-effective voice and data network solutions.


Issue 7: From The Guest Editors, David Hartshorn, Martin Jarrold Jun 2021

Issue 7: From The Guest Editors, David Hartshorn, Martin Jarrold

Online Journal of Space Communication

During the past 15 years, the international satellite communications industry has been developing and refining network solutions such that today, there are more than one million so-called Very Small Aperture Terminal (VSAT) systems installed and operating in more than 120 countries.


Space And Defense – Volume Twelve – Number One – Winter 2021, Space And Defense Journal Jun 2021

Space And Defense – Volume Twelve – Number One – Winter 2021, Space And Defense Journal

Space and Defense

No abstract provided.


Fluid-Structure Interaction Of Nrel 5-Mw Wind Turbine, Mohamed Sayed Elkady Abd-Elhay Jun 2021

Fluid-Structure Interaction Of Nrel 5-Mw Wind Turbine, Mohamed Sayed Elkady Abd-Elhay

Theses and Dissertations

Wind energy is considered one of the major sources of renewable energy. Nowadays, wind turbine blades could exceed 100 m to maximize the generated power and minimize produced energy cost. Due to the enormous size of the wind turbines, the blades are subjected to failure by aerodynamics loads or instability issues. Also, the gravitational and centrifugal loads affect the wind turbine design because of the huge mass of the blades. Accordingly, wind turbine simulation became efficient in blade design to reduce the cost of its manufacturing. The fluid-structure interaction (FSI) is considered an effective way to study the turbine's behavior …


Transport-Based Pattern Recognition Versus Deep Neural Networks In Underwater Oam Communications, Patrick L. Neary, Jonathan M. Nichols, Abbie T. Watnik, K. Peter Judd, Gustavo K. Rohde, James R. Lindle, Nicholas S. Flann Jun 2021

Transport-Based Pattern Recognition Versus Deep Neural Networks In Underwater Oam Communications, Patrick L. Neary, Jonathan M. Nichols, Abbie T. Watnik, K. Peter Judd, Gustavo K. Rohde, James R. Lindle, Nicholas S. Flann

Space Dynamics Laboratory Publications

Comparisons between machine learning and optimal transport-based approaches in classifying images are made in underwater orbital angular momentum (OAM) communications. A model is derived that justifies optimal transport for use in attenuated water environments. OAM pattern demultiplexing is performed using optimal transport and deep neural networks and compared to each other. Additionally, some of the complications introduced by signal attenuation are highlighted. The Radon cumulative distribution transform (R-CDT) is applied to OAM patterns to transform them to a linear subspace. The original OAM images and the R-CDT transformed patterns are used in several classification algorithms, and results are compared. The …


Satellite Security And Performance In An Era Of Dual Use, Joseph N. Pelton Jun 2021

Satellite Security And Performance In An Era Of Dual Use, Joseph N. Pelton

Online Journal of Space Communication

Since the mid-1990s the U.S. Government and military forces have placed more and more reliance on commercial satellite systems for military communications of a non-tactical nature. Requirements such as the U.S. Armed Forces Radio and Television require a great deal of bandwidth but do not require any special security protection. Further there are many other forms of communications involving national security or defense systems where a varying degree of security is required. Many of these applications do not require a very high level of "top secret" protection since these communications do involve tactical, strategic or highly classified messages. For instance, …


International Guidelines For The Preservation Of Space As A Unique Resource, Phillip D. Anz-Meador Jun 2021

International Guidelines For The Preservation Of Space As A Unique Resource, Phillip D. Anz-Meador

Online Journal of Space Communication

n/a


Overview: Satellite Signal Security: Copyright Protection Korean Dbs Content And Transaction Security, Don Flournoy Jun 2021

Overview: Satellite Signal Security: Copyright Protection Korean Dbs Content And Transaction Security, Don Flournoy

Online Journal of Space Communication

As a result of new developments in broadband communication, residential users, office workers and those who move from place to place have more ways to access the programming and services they want when they want them.


Space-Based Offensive Weapons: Have Policymakers Discussed This Enough?, Kathleen M. Sweet Jun 2021

Space-Based Offensive Weapons: Have Policymakers Discussed This Enough?, Kathleen M. Sweet

Online Journal of Space Communication

Arguably, one of the most significant global security policy debates of the 21st century is whether the United States and more specifically the Bush Administration should develop and deploy space-based weaponry. The age of space is upon us. But how convinced is the rest of America, the West and potential adversaries of the legitimate need to do so? For almost half a century, the world's space powers have abstained from deploying such weapons as basic unwritten policy. To date, the military has been limited to surveillance, navigation and communications satellites