Practical Engineering Approach Research Articles

Beampattern Synthesis and Optimization Method Based on Circular Frequency Diverse Array Engineering Model

The frequency diverse array (FDA) is capable of generating range-angle-dependent beampatterns by introducing a tiny frequency offset to the transmit carrier frequency of each array element. However, the beam-scanning potential of conventional linear FDA applications is limited, notably in their incapacity for 360° omnidirectional scanning. This paper introduces a method that leverages the geometric configuration of circular frequency diverse arrays (CFDAs) for synthesizing and optimizing beampatterns through a practical engineering approach. Initially, we compute the structural parameters and configurations of CFDA. Subsequently, the isophase plane is utilized to adjust the phase of each array element. Ultimately, the CFDA structure is used to optimize the non-uniform frequency offset, and the beampattern, which is capable of 360° omnidirectional scanning, is realized by low sidelobe optimization. Simulation results affirm that the CFDA antenna, as per the actual engineering model, possesses precise dot-shaped beampattern scanning abilities across both range and angle dimensions.

Achieving enhanced multifunctional performance for structural composite supercapacitors by reinforcing interfaces with polymer coating

Carbon fiber structural composite supercapacitors possess the multifunctionality of storing electrochemical energy and withstanding mechanical loads simultaneously, attracting increased attention in electric vehicles, drones, and aircraft sectors. A polymer-based coating was meticulously constructed at the electrode/electrolyte interface to enhance adhesion and stability between active materials and the carbon fiber fabric collector under diverse conditions, especially mechanical stress. Mechanical testing and corresponding physical characterization substantiated the superior performance of the polymer coating. With the protective polymer coating, the optimized structural composite Zn-ion supercapacitor (SZSC), consisting of carbon fiber@active carbon-P (CF@AC-P) cathode, ionogel electrolyte, and Zn anode, displayed a maximum energy density of 164.6 mWh kg−1, at power density of 563.3 mW kg−1. Moreover, the optimized SZSC demonstrated stable operation over more than 8000 cycles at 0.3 mA cm−2 without capacity degradation. The optimized SZSC exhibited a tensile strength of 399.7 MPa and Young's modulus of 11.5 GPa. Furthermore, employing vacuum infusion techniques, the fabricated three-dimensional (3D) wing skin model shell and tube shell curved-surface structural composite Zn-ion supercapacitor component composites showcased exceptional electrochemical performance. These achievements further validate the practicality of 3D multifunctional composites. Consequently, this research presented a practical and straightforward interface engineering approach to develop multifunctional structural devices with remarkable electrochemical and mechanical properties.

SN-MscaleDNN: A coupling approach for rapid shielding-scheme evaluation of micro gas-cooled reactor in the large design-parameter space

Rapid shielding-scheme evaluation in the large shielding-design parameter space (LSDPS) helps to optimize much better reactor shielding schemes. For this reason, a practical engineering approach utilizing a 1-D SN calculation and MscaleDNN network model is presented for accelerating reactor shielding-scheme evaluation in the LSDPS. We first review two commonly-used neural network-based methods for shielding-scheme evaluation and analyze their difficulties in the LSDPS through theoretical machine learning and data transformation analysis. Based on these discussions, the work transitions from method reviews to our two-step coupling solution to overcome these difficulties arising from high-frequency and multi-scale characteristics in the task. We first adopt equivalent 1-D SN calculations to quickly obtain inaccurate radiation dose rates at target points and then correct them by the frequency-scaled neural network MscaleDNN. The numerical results demonstrate that the proposed method achieves engineering-acceptable evaluation accuracy and higher accuracy than the conventional methods in the LSDPS.

Heat Conduction in Cylindrical Coordinates with Time-Varying Conduction Coefficients: A Practical Engineering Approach

This research aims to develop a mathematical method for expressing the Laplace operator in cylindrical coordinates and applying it to solve heat conduction equations in various scenarios. The method commences by transforming Cartesian coordinates into cylindrical coordinates and identifying the necessary substitutions. The result is the expression of the Laplace operator in cylindrical coordinates, which is subsequently employed to address heat conduction equations within cylindrical coordinates. Various cases encompassing different initial and boundary conditions, as well as variations in the conduction coefficient over time, are meticulously considered. In each instance, precise mathematical solutions are determined and subjected to thorough analysis. This study carries substantial implications for comprehending heat transfer within cylindrical coordinate systems and finds relevance in a wide array of scientific and engineering contexts. The research's findings can be harnessed for technology development, heating system design, and heat transfer modeling across diverse applications, including mechanical engineering and materials science. Therefore, the research's contribution holds paramount significance in advancing our understanding of heat transfer within cylindrical coordinates and in devising more efficient and accurate solutions for an array of heat-related issues within the realms of science and engineering.

A tale of two communities: Comparing user perceptions of condominial and conventional sewer systems in Salvador, Brazil

Problems of access and quality of sanitary sewage disproportionately impact the health of populations in urban peripheries of low-and middle-income countries. The condominial sewer system is a practical, low-cost, effective, and simplified engineering approach compared to conventional sewer systems. In support of meeting the sanitation needs in highly populated urban settings, there is a need to understand the residents’ perceptions regarding the advantages and disadvantages of this sanitation model compared to conventional sewer systems. We conducted a cross-sectional study from September to December 2021 in two urban communities of Salvador, Bahia, Brazil, where condominial and conventional sewer systems had been implemented in the last five years. Of the 203 residents we interviewed, 50.7% lived in a site served by a condominial sewer system. Residents in the condominial sewer site reported not connecting to public sewage network (23.7% vs. 11.2%; p = 0.022) more often than in the conventional site. They reported more collective action to solve urban sanitation problems (69.9% vs. 54.0%; p = 0.020), such as manhole cleaning and unclogging efforts to fix plumbing. Despite these challenges, these residents expressed that the current service quality is better than it was in the previous two years. Our results suggest that even within urban periphery communities of a large Brazilian city, disparities exist in access to and quality of sanitation services that may be linked to sewage system implementation. Implementing simplified sewer systems is important to meet the growing sanitation demands of urban areas. However, these systems should also play a role in reducing sanitation disparities and the adoption of participatory approaches to meet the needs of populations in the most disadvantaged conditions. Despite challenging conditions, there is the potential for community engagement and active participation in sanitation-related matters, which could enhance the implementation and long-term sustainability of these systems.

Heat-Treated Aramid Pulp/Silica Aerogel Composites with Improved Thermal Stability and Thermal Insulation.

In this work, we prepared heat-treated aramid pulp/silica aerogel composites (AP/aerogels) and investigated in detail the feasibility of improving thermal stability and thermal insulation via tailored heat treatment. The microstructure and FTIR spectra reveal that AP/aerogels are formed by a physical combination of the silica aerogel matrix and aramid pulps. When the heat treatment temperature increases, the density slightly decreases and then increases to the maximum due to the significant volume shrinkage. The pyrolysis of aramid pulp and the collapse of silica skeletons occur during heat treatment; nevertheless, the typical structures of AP/aerogels do not change significantly. It is also found that both the hydrophobicity and the thermal insulation decrease with the increasing heat treatment temperature. We note that when the heat treatment is at 600 °C, the AP/aerogel still maintains a low density of 0.19 g/cm3 and a contact angle of 138.5°. The thermal conductivity is as low as 26.11 mW/m/K, measured using the transient hot wire method. Furthermore, the heat-treated AP/aerogels can avoid heat shock and possible thermal hazards during practical thermal insulation applications. The onset temperatures of the thermal decomposition of AP/aerogels increase from 298.8 °C for an untreated one to 414.7 °C for one treated at 600 °C, indicating that the thermal stability of AP/aerogels is improved significantly. This work provides a practical engineering approach to expand the thermal insulation applications of silica aerogel composites.

Arctic naval launch and recovery operations, under ice impact interactions

This study analyses dynamic influence of stochastic vibro-impact ship behaviour on the ship's launch and recovery capability. To deliver cargo and people to the Arctic regions, ships must withstand harsh environmental conditions and interact with large floating ice pieces. This interaction may result in impact-type loading of a ship hull by ice, preventing planned navigation and even causing to abort of some routine launch and recovery operations of delivering cargo or other equipment. The major safety concern is the risk of collision between the payload and the mother ship hull. The ship-based crane, which served for conducting launch and recovery operations, was assumed to be rigid, mimicking the ship dynamics, whereas the payload is modelled as a single-degree-of-freedom pendulum. This study advocates practical engineering approach, applicable to various scenarios with vessels operating in relevant in situ environmental sea and ice conditions. The proposed study intends to contribute to improving launch and recovery operational reliability, as well as motion control, especially in Arctic aquatic regions. When mentioning Arctic and defence technologies, launch and recovery systems have significant relevance for unmanned vehicles onboard ships.

Understanding Frugal Engineering Process for Frugal Innovations: Socially Conscious Designs for Homeless Individuals, A Case Study

This paper presents the results of a case study regarding understanding frugal engineering design and process methodology through the fabrication of wearable tent-jackets for the protection of homeless individuals. Frugal innovations are being investigated for socially conscious products, but an understanding of frugal engineering methodology remains unexplored and is the focus of this research. Multiple socio-economic drivers are resulting in a lack of access to basic human needs such as housing, healthcare, etc. across the globe. Frugal engineering presents an equitable and practical engineering approach to address these challenges and merits exploring a methodology for innovations. In this paper, an origami-based design approach was employed to create a functional prototype of a tent for shelter that can be morphed into a wearable weather protection jacket. We call it a “wearable tent”. The prototype was successfully fabricated using a reusable material that is used abundantly in the construction industry. The functional prototype was tested for its efficacy and effectiveness in terms of weight, strength, and ease of switching between the two configurations. The results suggest a potential model that could be explored and applied for socially conscious engineering design solutions for such severely resource-constrained cases for disadvantaged communities with future potential for digitally disadvantaged enterprises.

Predicting the tensile stiffness and strength properties of plain woven carbon fiber/epoxy laminates: a practical analytical approach and experimental validations

The difficulties in establishing an analytical model for plain woven fabric composites (PWFC) and its implementation are well-accepted due to the complexity of yarn architecture, approximations assumed, and lack of experimental validations. In this paper, a practical engineering approach is proposed to predict the tensile properties of PWFC. The approach assumes PWFC as cross-ply, the undulation angle an elliptical shape. The approach tremendously simplifies the calculation keeping a close agreement with the tensile experimental results of PWFC. The approach is remarkably compatible with other theoretical models and experiments that existed in the literature.

An engineering approach for the prediction of fatigue damage in the part load regime

Due to the volatile electricity received from solar and wind power plants, the energy market requires highly variable hydropower machines which are able to cope with fast changes of their operating regimes. With the need for flexible operation, Francis runners are exposed to various operating conditions outside the traditional operating range. Hence, the runners must be specifically designed for long time part load operation to meet hydraulic and structural requirements. Therefore, it is inevitable to have a reliable but also practical engineering approach in the design phase of the projects in order to ensure sufficient fatigue life of the Francis runners. Deep part load operation mainly consists of stochastic loads acting on the runner blades. Previous publications show that it is reasonable to normalize the Rainflow matrix of stress amplitudes to represent the characteristic behaviour at deep part load operation. Hence, it is feasible to utilize the normalized Rainflow matrix to predict the fatigue damage of Francis runner designs without prototype measurements. Within this paper, a scaling method to derive project specific fatigue results for deep part load is introduced and subsequently validated through an intercomparison of available strain gauge measurement data and prediction. Based on the results, the accuracy of the proposed engineering approach and possible impacts of different boundary conditions are discussed.

A practical approach to predict the flexural properties of woven plain carbon fiber/epoxy laminates

Analytical predictions of woven plain fabric composite (WPFC) mechanical properties based on the existing models still remain a formidable task due to complex fiber architecture. Therefore, there has been a strong need for a simplified, practical approach to determining the mechanical properties of structural members laminated with WPFC. This paper proposes a practically useful engineering approach to predict the flexural properties of WPFC. The analytical solution of the developed approach was compared to the results of experimental flexural tests performed with three-point bending test specimens. Experimental findings and the results obtained from the practical engineering approach showed a good agreement.

Water Saturation Modeling Challenges in Oil-Down-to Wells: An Example from a Multidarcy North Sea Reservoir

Summary The initial water saturation in a reservoir is important for both hydrocarbon volume estimation and distribution of multiphase flow properties such as relative permeability. Often, a practical reservoir engineering approach is to relate relative permeability to flow property regions by binning of the initial water saturation. The rationale behind this approach is that initial water saturation is related to both the pore-throat radius distribution and the wettability of the rock, both of which affect relative permeability. However, pore-throat radius and wettability are usually not explicitly included in geomodel property modeling. Therefore, the saturation height model should not only capture an average hydrocarbon pore volume but also reflect the underlying mechanisms from hydrocarbon migration history and its impact on initial water saturation distribution. This work introduces and describes a new term, excess water, for more precise classification of saturation height model scenarios in reservoirs in which multiple mechanisms have interacted and caused a complex water saturation distribution. An example of the presence of transition zones related to drained local perched aquifers (excess water) in oil-down-to (ODT) wells is shown using a limited data set from a North Sea reservoir. The physical basis for drainage and imbibition transition zones connected to both regional and perched aquifers is given. The distribution of initial water saturation in reservoirs containing excess water is demonstrated through numerical modeling of oil migration over millions of years. Highly permeable reservoirs are more likely to have locally trapped water because of lower capillary forces. A static situation occurs in areas where the capillary forces cannot maintain a high enough water saturation for further water drainage. On the other hand, both high- and low-permeability reservoirs may have significant excess water because of ongoing dynamic effects. In both cases, long distances for water to drain laterally to a regional aquifer enhance the possibility for a dynamic excess water situation.

A Service-Oriented Approach for Sensing in the Internet of Things: Intelligent Transportation Systems and Privacy Use Cases

This paper presents a Sensing-as-a-Service run-time Service Oriented Architecture (SOA), called 3SOA, for the development of Internet of Things (IoT) applications. 3SOA aims to allow interoperability among various IoT platforms and support service-oriented modelling at high levels of abstraction where fundamental SOA theories and techniques are fully integrated into a practical software engineering approach. 3SOA abstracts the dependencies of the middleware programming model from the application logic. This abstraction allows the development efforts to focus on writing the application logic independently from hardware platforms, middleware, and languages in which applications are programmed. To achieve this result, IoT objects are treated as independent entities that may interact with each other using a well-defined message exchange sequence. Each object is defined by the services it provides and the coordination protocol it supports. Objects are then able to coordinate their resources to address the global objectives of the system. To practically validate our proposals, we demonstrate an intelligent transportation system and data privacy functional prototypes as proof of concepts. The use cases show that 3SOA and the presented abstraction language allow the amalgamation of macroprogramming and node-centric programming to develop real-time and efficient applications over IoT.

Flame spread simulation of fire occurrence at motorcycle parking building

This research is motivated by the condition of the parking building in A Campus, State University of Jakarta that development that very compact and crowded with wide openings. This study aims to estimate the flame spread of motorcycle parking. This study used computer fire modeling by simulating flame starting point and direction of the wind, numbers of fuel source and forms. This research will discuss about the development of the fire where the fire development will be represented by HRR (Heat Release Rate), burning rate, and visualization of each simulation. This step is very advantageous because it can figure out how the spread of fire during a fire and how fire simulated. With the fire of this modeling can be a practical engineering approach to provide additional review of aspects of fire safety on campus parking building at Jakarta State Univeristy. From these results it can be concluded that the rapid spread of the fire affected by the starting point of fire, wind speed and direction. HRR where the greater value the greater the value of burning rate obtained and the greater the level of occurrence of fire.

Emerging Trends in Techniques and Technology as Applied to Filter Design

In the last decade, the filter community has innovated both design techniques and the technology used for practical implementation. In design, the philosophy has become “if you can't avoid it, use it”, a very practical engineering approach. Modes previously deemed spurious are intentionally used to create in-line networks incorporating real or imaginary transmission zeros and also reduce the number of components and thus further miniaturize; spurious responses are re-routed to increase the passband width or stopband width, frequency variation in couplings is used to create complex transfer functions, with all of these developments using what was previously avoided. Clever implementations of baluns into passive and active networks is resulting in a new generation of noise-immune filters for 5G and beyond. Finally, the use of a diakoptic approach to synthesis has appeared an evolving approach in which small blocks (“singlets”, “doublets”, etc.) are cascaded to implement larger networks, (reducing the need for very complex synthesis), with this new approach promising a large impact on the implementation of practical structures. Filter technology has migrated towards “observe it and then adapt it”, pragmatically repurposing tools not specifically originally intended for the applications. Combinations of surface wave and bulk wave resonators with L-C networks are improving the loss characteristics of filters in the region below 2 GHz. Lightweight alloys and other materials designed for spacecraft are being used in filters intended for space, to provide temperature stability without the use of heavy alloys such as Invar. Fully-enclosed waveguide is being replaced in some cases by planar and quasiplanar structures propagating quasi-waveguide modes. This is generically referred to as SIW (Substrate Integrated Waveguide). Active filters trade noise figure for insertion loss but perhaps will offer advantage in terms of size and chip-level implementation. Finally, the era of reconfiguration might be approaching, as the basic networks are evolving, perhaps lacking only the appearance of lower-loss, higher-IP solid-state tuning elements.

Kontrolisanje zaostalih napona - razvoj najnovijih inženjerskih metoda za merenje bez razaranja i povoljnu preraspodelu zaostalih napona

Welding is used widely in the automotive industry for joining a variety of structural components and parts. Of paramount importance in these structures are their engineering properties, such as fatigue life, distortions, dimensional stability and corrosion resistance that can be affected considerably by the presence of residual stresses (RS). The knowledge of RS and the ability to control their distribution in welded structures is critical when evaluating their fatigue life and preventing catastrophic failures. An engineering concept of residual stress management (RSM) has been developed that addresses all aspects of residual stresses in structural elements. RSM includes three major stages in stress management, i.e. RS determination, RS analysis and RS redistribution. Using this approach, stresses in structures and materials can be evaluated in each specific case either theoretically or experimentally and the performance and fatigue behavior of such structures optimized. This paper is built as an overview of the RSM concept and its application in the fields of non-destructive measurement of residual and applied stresses and in treatment of structures with residual stresses to achieve better performance and longer fatigue life. All three stages of the RSM concept will be discussed and for each of the stages practical engineering approach examples will be given. An example of a project in which the residual stress distribution in a filet welded joint was measured, analyzed and changed by post-weld treatment will be presented to demonstrate the effectiveness of the RSM approach. The advancements in the modern tools used in this project for non-destructive measurement of residual stresses using an ultrasonic computerized complex for residual stress measurement and the ultrasonic peening for redistribution of the residual stresses that allowed improving the quality of the welds and increasing their fatigue life will also be presented.

Performance of a Magnus effect-based cylindrical roll stabilizer on a full-scale Motor-yacht

The rotor stabilizer systems based on the Magnus principle are among the alternative systems used as an anti-rolling system. The key objective of this paper is to extensively study the performance of the Magnus stabilizer on a ship's roll-heave motions in a regular beam sea and at low velocity, as well as to investigate the hydrodynamic characteristics of the rotating cylinder in the varied diameters and rotation speeds. Two-dimensional rotating cylinders and three-dimensional ship-rotor cases are simulated using the RANS solver by adopting SST k-ω turbulence model. Flow past a rotating cylinder is computed with cylinder diameter-based Reynolds Numbers of 7.33 × 105, 1.01 × 106 and 1.26 × 106 in the spin ratio range of 1.52 < α < 13.09. The rotational motion of the cylinder is simulated by the rotating wall approach. The lift forces obtained from two-dimensional analyses are applied externally as damping moments to examine the effect of Magnus stabilizer on the dynamic motions of the full-scale motor yacht. The results indicate that the increased diameter is effective on the lift force than increased rotation speed. The ship-rotor interaction is successfully modeled by external moment application as a practical engineering approach. Magnus stabilizer presents a high-performance in roll reduction that varies between 9.13% and 85.84%.

How dimensional analysis allows to go beyond Metzner–Otto concept for non-Newtonian fluids

Abstract The concept of Metzner and Otto was initially developed for correlating power measurements in stirred vessels for shear-thinning fluids in the laminar regime with regard to those obtained for Newtonian liquids. To get this overlap, Metzner and Otto postulated and determined an “effective shear rate” which was proportional to the rotational speed of the impeller Although it was not based on a strong theoretical background, it was rapidly admitted as a practical engineering approach and was extended for seeking out a “Newtonian correspondence” with non-Newtonian results (i.e. different classes of fluids). This was applied in a variety of tank processes even for predicting heat transfer or mixing time, which stretches far away from the frame initially envisaged by Metzner and Otto themselves. This paper aimed to show how dimensional analysis offers a theoretically founded framework to address this issue without the experimental determination of effective quantities. This work also aimed to enlarge the underlying questions to any process in which a variable material property exists and impacts the process. For that purpose, the pending questions of Metzner and Otto concept were first reminded (i.e. dependence of the Metzner–Otto constant to rheological parameters, physical meaning of the effective shear rate, etc.). Then, the theoretical background underlying the dimensional analysis was described and applied to the case of variable material properties (including non-Newtonian fluids), by introducing in particular the concept of material similarity. Finally, two examples were proposed to demonstrate how the rigorous framework associated with the dimensional analysis is a powerful method to exceed the concept of Metzner and Otto and can be adapted beyond the Ostwald–de Waele power law model to a wide range of non-Newtonian fluids in various processes, without being restricted to batch reactor and laminar regime.

Verifiable Self-Aware Agent-Based Autonomous Systems

In this article, we describe an approach to autonomous system construction that not only supports self-awareness but also formal verification. This is based on modular construction where the key autonomous decision making is captured within a symbolically described “agent.” So, this article leads us from traditional systems architectures, via agent-based computing, to explainability, reconfigurability, and verifiability, and on to applications in robotics, autonomous vehicles, and machine ethics. Fundamentally, we consider self-awareness from an agent-based perspective. Agents are an important abstraction capturing autonomy, and we are particularly concerned with intentional, or rational, agents that expose the “intentions” of the autonomous system. Beyond being a useful abstract concept, agents also provide a practical engineering approach for building the core software in autonomous systems such as robots and vehicles. In a modular autonomous system architecture, agents of this form capture important decision making elements. Furthermore, this ability to transparently capture such decision making processes, and especially being able to expose their intentions, within an agent allows us to apply strong (formal) agent verification techniques to these systems.

Influence of groove parameters on the thermal hydraulic performance of a composite porous vapor chamber: A numerical study

Composite porous vapor chamber (CPVC) with uniform radial grooves in the evaporator wick demonstrated good thermal hydraulic performance at high heat flux. To reveal the effects of groove parameters on the performance of CPVCs, the temperature, velocity and pressure distributions of CPVCs were analyzed based on a simplified numerical model. Qualitative and quantitative results indicated that: (1) the influence of groove parameters were contradictory; larger parameter values could enhance the thermal performance and benefit the vapor flow, while smaller ones would facilitate the liquid circulation and reduce the maximum pressure drop; (2) the groove width and the number of grooves had more influence on the temperature and velocity distributions, while the effect of the diameter of the circular cavity on the maximum pressure drop was larger; (3) the performance of CPVCs could be obviously improved by adding a wick column at the center of the evaporator wick, which eliminated the risk of insufficient capillary pressure. The study potentially provides a practical engineering approach for the analysis of wicks with multi-artery channels, and a qualitative basis for determining appropriate groove parameters.