1,667 research outputs found

    Implementation of Automatic DC Motor Braking PID Control System on (Disc Brakes)

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    The vital role of an automated braking system in ensuring the safety of motorized vehicles and their passengers cannot be overstated. It simplifies the braking process during driving, enhancing control and reducing the chances of accidents. This study is centered on the design of an automatic braking device for DC motors utilizing disc brakes. The instrument employed in this study was designed to accelerate the vehicle in two primary scenarios - before the collision with an obstacle and upon crossing the safety threshold. It achieves this by implementing the Proportional Integral Derivative (PID) control method. A significant part of this system comprises ultrasonic sensors, used for detecting the distance to obstructions, and rotary encoder sensors, which are utilized to measure the motor's rotational speed. These distance and speed readings serve as essential reference points for the braking process. The system is engineered to initiate braking when the distance value equals or falls below 60cm or when the speed surpasses 8000rpm. During such events, the disc brake is activated to reduce the motor's rotary motion. The suppression of the disc brake lever is executed pneumatically, informed by the sensor readings. Applying the PID method to the automatic braking system improved braking outcomes compared to a system without the PID method. This was proven by more effective braking results when the sensors detected specific distance and speed values. Numerous PID tuning tests achieved optimal results with K_p = 5, K_i = 1, and K_d = 3. These values can be integrated into automatic braking systems for improved performance. The PID method yielded more responsive braking outcomes when applied in distance testing. On the contrary, the braking results were largely unchanged in the absence of PID. Regarding speed testing, the PID method significantly improved the slowing down of the motor speed when it exceeded the maximum speed limit of 8000 rpm. This eliminates the possibility of sudden braking, thus maintaining the system within a safe threshold. The average time taken by the system to apply braking was 01.09 seconds, an indication of its quick responsiveness. This research is a valuable addition to control science, applying the PID control method to automatic DC motor braking. It provides valuable insights and concrete applications of PID control to complex mechatronic systems. It is also noteworthy for its development and optimization of suitable PID parameters to achieve responsive and stable braking. The study, therefore, offers a profound understanding of how PID control can be employed to manage braking systems on automatic DC motors, thereby advancing knowledge and application of control in control science and mechatronics

    Central Iowa Expo Pavement Project: Phase IV Performance Assessment Experimental Test Plan_ TR-817

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    Approximately 4.8 miles of roadways at the Central Iowa Expo facility in Boone, Iowa, were reconstructed in 2012 as part of Iowa Highway Research Board (IHRB) project TR-671. The project included three phases encompassing construction and field testing to assess the performance of several pavement foundation technologies. The Iowa Department of Transportation (DOT) has approved a Phase IV project to assess the long-term performance of the pavements evaluated in Phases I through III. This report provides recommendations for two experimental test plan alternatives for Phase IV, one outlining a minimum recommended scope and another outlining a comprehensive scope to more precisely quantify differences among test sections. The overall goal of the testing program is direct measurement of not only the in situ mechanistic input parameters necessary for AASHTOWare Pavement ME Design but also the impacts of seasonal variations in the measurement values. The report includes a statistical analysis of the data from Phases I through III and, based on this analysis, recommendations regarding the specific sections to test as well as the number and type of tests to perform. The methods proposed for Phase IV field testing include automated plate load testing, core hole permeability testing, and dynamic cone penetrometer testing. The report also summarizes engineering measurement values to be obtained for each test. Tests will be conducted in fall 2023, spring 2024, fall 2024, and spring 2025

    SIMULATING CONSUMABLE ORDER FULFILLMENT VIA ADDITIVE MANUFACTURING TECHNOLOGIES

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    Operational availability of naval aircraft through material readiness is critical to ensuring combat power. Supportability of aircraft is a crucial aspect of readiness, influenced by several factors including access to 9B Cognizance Code (COG) aviation consumable repair parts at various supply echelons. Rapidly evolving additive manufacturing (AM) technologies are transforming supply chain dynamics and the traditional aircraft supportability construct. As of June 2022, there are 595 AM assets within the Navy’s inventory—all for research and development purposes. This report simulates 9B COG aviation consumable fulfillment strategies within the U.S. Indo-Pacific sustainment network for a three-year span, inclusive of traditional supply support avenues and a developed set of user-variable capability inputs. Simulated probabilistic demand configurations are modeled from historical trends that exploit a heuristic methodology to assign a “printability” score to each 9B COG requirement, accounting for uncertainty, machine failure rates, and other continuous characteristics of the simulated orders. The results measure simulated lead time across diverse planning horizons in both current and varied operationalized AM sustainment network configurations. This research indicates a measurable lead time reduction of approximately 10% across all 9B order lead times when AM is employed as an order fulfillment source for only 0.5% of orders.NPS Naval Research ProgramThis project was funded in part by the NPS Naval Research Program.Lieutenant Commander, United States NavyApproved for public release. Distribution is unlimited

    Advanced Testing of Soft Polymer Materials

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    Manufacturers of soft polymer products, as well as suppliers and processors of polymers, raw materials, and compounds or blends are compelled to use predictive and advanced laboratory testing in their search for high-performance soft polymer materials for future applications. The collection of 12 publications contained in this edition therefore presents different methods used to solve problems in the characterization of various phenomena in soft polymer materials, asks relevant questions and offers appropriate solutions

    Development of numerical and experimental tools for the simulation of train braking operations

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    L'abstract è presente nell'allegato / the abstract is in the attachmen

    Computational and Experimental Investigation of Conventional and Cryogenic Cooling in Milling Operations

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    In machining, high thermo-mechanical loads which limit tool life and efficiency are often managed using coolants. Appropriate coolant selection and well targeted application can transport significant thermal loads away from the cutting region, along with providing lubrication and aiding in chip evacuation. In this work, numerical and experimental studies of coolant applications contribute to both increasing fundamental understanding of coolant behaviours and supporting the design of improved cutting tools. A multiphase conjugate heat transfer computational fluid dynamics (CFD) model is developed in OpenFOAM to study both the coolant coverage and tool temperatures during the application of an oil-water emulsion coolant in milling processes via through-tool channels. Utilising this model to investigate a standard tool design has shown the coolant jet is targeted near to the cutting edge, with coolant spreading out to cover the tool and workpiece surfaces to provide good coverage along the cutting edge. To support the development of improved tool designs, the CFD model has been further utilised in an exploration of the coolant channel design space and optimisation study. As well as providing new tool designs with minimised tool temperatures and maximised coolant coverage in this study of the design space, key physical features such as a shift in coolant spreading behaviour and the presence of designs with significant levels of splashing have been identified for the first time. Cryogenic coolants provide a cleaner alternative to oil-water emulsion coolants in cutting operations. Liquid CO2 is one such coolant which has shown promise in experimental machining tests. To build towards the development of a CO2 CFD model which can support innovation of tool designs to maximise the benefits of this new coolant, fundamental experimental and modelling work is presented in this thesis. An experimental rig design has been developed to analyse heat transfer when using CO2 coolants in a simplified setting and this has been used to successfully validate a CFD model capturing the conjugate heat transfer when using liquid CO2 coolant

    An Investigation Into the Economic Useful Life of Commercial Aircraft as Impacted by Maintenance and Economic Variables

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    This research involved examining the economic useful life of commercial aircraft and the impact of maintenance and economic variables on the viability and longevity of the asset. The data sample consisted of the entire population of Boeing commercial aircraft produced between 1956 and 2021. The objective was to determine the effect of both maintenance and economic variables on the longevity and usefulness of commercial aircraft. As manufacturers work with issues such as service life, economic life, safety, and critical design features, those in the aviation community focus on the operational side of the equation––how long can one operate the asset, and at what point is it no longer effective to continue investing into the asset? The research presents an extensive review of the maintenance and technological advances in commercial aircraft over the last 60 years and an investigation of various aspects of the economic useful life concept in both use and application from an appraisal and industry perspective. The research focus is on the actual age at which an asset is removed from operational service and the underlying causes of such a decision

    Environmental Impact Assessment by Green Processes

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    Primary energy consumption around the world has been increasing steadily since the Industrial Revolution and shows no signals of slowing down in the coming years. This trend is accompanied by the increasing pollutant concentration on the Earth’s biosystems and the general concerns over the health and environmental impacts that will ensue. Air quality, water purity, atmospheric CO2 concentration, etc., are some examples of environmental parameters that are degrading due to human activities. These ecosystems can be safeguarded without renouncing industrial development, urban and economic development through the use of low environmental impact technologies instead of equivalent pollutant ones or through the use of technologies to mitigate the negative impact of high emissions technologies. Pollutant abatement systems, carbon capture technologies, biobased products, etc. need to be established in order to make environmental parameters more and more similar to the pre-industrialization values of the planet Earth. In 15 papers international scientists addressed such topics, especially combining a high academic standard coupled with a practical focus on green processes and a quantitative approach to environmental impacts
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