Practical Design Issues Research Articles

Displacement-potential analysis of ply-stresses in a partially guided non-uniform short-column of hybrid laminated composites

Reliable and accurate analysis of local stresses in structural problems of fiber-reinforced laminated composites involving nonuniform geometry is of utmost practical importance, especially when they are subjected to local loads and supports. In this research, a new study of ply stresses in a partially guided, nonuniform, short composite column of hybrid laminates, subjected to an eccentrically distributed loading is conducted using an efficient computational scheme. The analytical modeling of the present mixed-boundary-value problem of laminated structure is realized in terms of a single scalar function of space variables (called as displacement-potential function), which is defined by the displacement components of plane elasticity, and is governed by a single fourth-order partial-differential equation of equilibrium. In this modeling approach, the original three-dimensional symmetric laminated column is reduced to a plane-stress scalar-field problem of an equivalent imaginary lamina in an attempt to obtain the corresponding strain field (global laminate strain), which is then used to determine the stress fields of individual plies through the respective transformed reduced stiffness matrices. A finite-difference based computational scheme is developed to solve the representative nonuniform equivalent lamina in terms of the displacement-potential function, which is however well capable of dealing with different ply materials as well as fiber orientations, together with the associated mixed and changeable physical conditions along the boundaries of the column. A 28-ply balanced hybrid laminate composed of boron-epoxy and glass-epoxy plies with various fiber orientation is considered as the structural material for the present column. The stress fields obtained for individual plies as well as the overall laminate are analyzed in the perspective of a number of practical issues of structural design, which include material hybridization, eccentricity of loading and attachment of partial guides to the column. The design stresses of the nonuniform laminated column are identified to be affected significantly by the material and orientation of fibers as well as the laminate hybridization. An attempt is also made to verify the soundness and accuracy of the present computational scheme through the comparison of the present potential-function solutions with those obtained by the conventional computational method.

Deep Learning Aided Intelligent Reflective Surfaces for 6G: A Survey

The envisioned sixth-generation (6G) networks anticipate robust support for diverse applications, including massive machine-type communications, ultra-reliable low-latency communications, and enhanced mobile broadband. Intelligent Reflecting Surfaces (IRS) have emerged as a key technology capable of intelligently reconfiguring wireless propagation environments, thereby enhancing overall network performance. Traditional optimization techniques face limitations in meeting the stringent performance requirements of 6G networks due to the intricate and dynamic nature of the wireless environment. Consequently, Deep Learning (DL) techniques are employed within the IRS framework to optimize wireless system performance. This paper provides a comprehensive survey of the latest research in DL-aided IRS models, covering optimal beamforming, resource allocation control, channel estimation and prediction, signal detection, and system deployment. The focus is on presenting promising solutions within the constraints of different hardware configurations. The survey explores challenges, opportunities, and open research issues in DL-aided IRS, considering emerging technologies such as digital twins (DTs), computer vision (CV), blockchain, network function virtualization (NFC), integrated sensing and communication (ISAC), software-defined networking (SDN), mobile edge computing (MEC), unmanned aerial vehicles (UAVs), and non-orthogonal multiple access (NOMA). Practical design issues associated with these enabling technologies are also discussed, providing valuable insights into the current state and future directions of this evolving field.

Augmenting sparse arrays in ocean acoustics: A Gaussian Process approach

Source localization and geoacoustic inversion performance depends on the location of receiving phones, their spacing, their number, and the array aperture. Performance suffers when practical design issues limit the capabilities of the array. In this work, sparse arrays are augmented leading to the generation of virtual arrays for better sampling of the ocean and, thus, improved estimation performance. To that effect, Gaussian Processes are employed, which are shown to create high-fidelity field “measurements” at virtual, densely spaced hydrophones. Kernel functions are key building blocks in the implementation of Gaussian Processes, as they quantify the field coherence at neighboring spatial points. Functions of interest are the squared exponential, Matern, and plane wave kernels. We validate our method with application to synthetic data as well as data collected during the Seabed Characterization Experiment conducted in 2022. [Work supported by ONR.]

The potential of combining passenger rail with freight: A New York City case study

Utilizing passenger rail, including subways, to transport goods can have advantages over trucking in terms of efficiency and emissions. While some experimentation is ongoing in this area, combined passenger and rail opportunities in specific cities merit further attention. To more concretely examine how to leverage passenger rail for freight, this paper explores the potential of utilizing unused capacity in New York City (NYC) subway trains for transporting goods. Using General Transit Feed Specification (GTFS), rail and passenger data for the NYC subway, we found ways to use excess capacity and existing rail lines for freight transportation. We visualized a freight train timetable and graph, analyzed meet-errors between freight and passenger trains, and formulated prevention policies. Using U.S. Environmental Protection Agency data, we estimated emission reductions from replacing trucks with unused subway capacity. Our findings suggest that with adequate policies, investments and redesign, combining passenger rai and freight in the subways could significantly reduce truck trips, traffic congestion, and greenhouse gas emissions compared to trucking alone. However, implementing this approach requires careful collaborative planning, investment, enhanced security screening, and streamlined operations to minimize impacts on passenger transport. Further efforts should explore in more depth the costs and benefits and practical design and policy issues around using excess passenger rail capacity for freight transport in NYC and other cities.

Optimizing PV integration: Addressing energy fluctuations through BIPV and rooftop PV synergy

The widespread availability and affordability of photovoltaic (PV) systems are driving the future of demand-side generation towards end-user-based PV plants. Building-integrated PV systems offer an additional source of electrical energy, but their power output depends on external factors like solar insolation, weather conditions, geographical location, and earth’s rotation, causing non-constant energy generation, even in ideal weather conditions. In grid-connected systems, this variability leads to fluctuations in grid demand. Both BIVP and rooftop PV systems are photovoltaic-based, but their installation differences result in distinct energy generation characteristics. To address this, we propose an innovative approach to optimally integrate BIPV and rooftop PV systems by leveraging their contradictory energy generation nature. By employing mathematical and evolutionary algorithms to design an optimal system and develop a multi-objective optimization model, we address practical design issues. The outcome of these single and multi-objective systems helps minimize fluctuations in grid dependency throughout the year. The proposed system is validated on the IEEE-33 bus radial distribution network using the B&R X20CP1586 PLC, confirming its effectiveness in ensuring a stable and reliable grid performance while mitigating energy fluctuation impacts.

A novel comprehensive optimal PMU placement considering practical issues in design and implementation of a wide-area measurement system

• Several WAMS-based applications are considered in the OPP problem. • Concept of the line-wise observability is presented. • Observability of multi-TSO power systems in the OPP problem is investigated • The proposed OPP model is originally a MILP one and its global solution can be easily found. Since phasor measurement units (PMUs) are increasingly installed in power systems, many research works have investigated the optimal PMU placement (OPP) problem with the sake of maximizing observability over the power grid, while minimizing the cost of purchasing PMUs. However, there are still some practical challenges that have not been considered in the previous research studies, and are needed to be addressed for a real wide-area measurement system (WAMS) implementation. In this paper, a comprehensive OPP model is proposed which employs a set of basic and novel constraints for a WAMS design. In this regard, the line-wise observability concept is proposed for the first time to consider the requirements of observability for a range of WAMS-based applications such as restoration management, model validation of power system components, and dynamic line rating (DLR) monitoring. In addition, observability constraints for multi-transmission system operator (multi-TSO) power systems that are operated by different legal entities are provided, which can considerably affect the OPP result. The proposed model is formulated based on a mixed-integer linear programming (MILP) formulation which enables the optimization problem to be solved easily and effectively by existing commercial optimization tools, without any need for linearization. The performance of the proposed OPP model is first verified through simulation results on an 86-bus real power system. Then, simulations are applied to IEEE 118-bus and 300-bus test systems, to certify the performance of the proposed model in comparison with other OPPs in the literature.

Throughput Guarantees for Multi-Cell Wireless Powered Communication Networks With Non-Orthogonal Multiple Access

The emerging non-orthogonal multiple access (NOMA) technology can effectively improve the throughput performance of Internet of Things (IoT) devices. Besides throughput maximization, ensuring throughput fairness is a practical design issue when implementing NOMA in wireless powered communication networks (WPCN). To this end, we investigate the joint transmission time and power allocation problem for NOMA communication, aiming to improve the sum-throughput while guaranteeing different wireless devices’ (WDs’) throughput in multi-cell WPCN. In particular, we first analyze the feasibility of the problem by deriving the necessary and sufficient conditions for the existence of feasible solutions and propose an efficient algorithm to obtain the set of feasible values of transmission time allocation. We then propose an efficient algorithm for the transmission time allocation to improve the sum-throughput. During each search iteration, we adopt the successive convex approximation (SCA) approach to transform the non-convex power allocation problem into a sequence of convex problems and obtain the locally optimal transmit power under a fixed transmission time. Numerical simulations show that the proposed algorithm can improve the sum-throughput while guaranteeing each WD’s throughput.

Design of thin steel battens subject to pull-through failures

Localized pull-through failures of cold-formed steel roof battens have often been observed at the roof batten to purlin/rafter/truss screw connections during storms and cyclones. Recent research studies have therefore proposed improved design capacity equations by undertaking both experimental studies and finite element analyses. However, they have not investigated the effects of very thin steel roof and ceiling battens (<0.50 mm), safety lip features and purlin flexibility on the localized pull-through failures. Hence this study was aimed at investigating the effects of all such practical design issues and to assess the suitability of current design equations. For this purpose, a series of static and fatigue pull-through failure tests of roof and ceiling battens was undertaken under simulated static and cyclic wind uplift loads. This paper presents the details and results obtained from this study including suitable design recommendations. It has shown that the recently developed pull-through capacity equations can be used for very thin steel battens. Higher capacity reduction factors are recommended for use with these design equations for battens made of Australian cold-formed steels used in this study. The use of safety lip features did not affect the static pull-through capacities, but it improved the fatigue performance of roof battens. Finally, the suitability of using low strength steel battens instead of high strength steel battens was evaluated.

Low-Power SAR ADC Design: Overview and Survey of State-of-the-Art Techniques

This paper presents an overview for low-power successive approximation register (SAR) analog-to-digital converters (ADCs). It covers the operation principle, error analysis, and practical design issues. Furthermore, this paper provides a comprehensive survey of state-of-the-art low-power design techniques for every circuit block in the SAR ADC, including comparator, capacitive digital-to-analog converter (DAC), and SAR logic. The goal of this paper is to provide a useful overview to SAR ADC designers who want to improve the energy efficiency targeting low-to-medium speed applications.

An optimal far field radiation pattern synthesis of mutually coupled antenna arrays

This article presents a precise approach for far-field radiation pattern (FFRP) correction of mutually coupled discrete dipole element (DDE) array of monopole antennas and concentric circular antenna array (CCAA) of dipole elements by employing the parametric assimilation technique (PAT). The effect of mutual coupling is a crucial part of any practical antenna array design issue. Various techniques have been suggested to calculate, compensate and reduce the mutual coupling effect during the last few decades. This article shows an exact method for mutual coupling inclusive corrected radiation pattern synthesis using PAT. The parameters of mutual impedance are calculated and assimilated with the values of the desired radiation pattern. The employed technique is cost-effective, less complex and easy to implement while achieving better performance for mutually coupled DDE array and CCAA synthesis. Grey wolf optimisation (GWO) is a state-of-the-art stochastic algorithm applied here to find the optimal values of the current amplitude excitation weights and the inter-element spacing between each element of the array in the DDE array and three-rings structure CCAA for the desired, uncorrected and corrected FFRP synthesis. Some well-established evolutionary optimisation techniques like particle swarm optimisation (PSO), differential evolution (DE) and social spider algorithm (SSA) are also employed in this article for the sake of comparison with the results achieved by using the GWO algorithm. Finally, the supremacy of GWO algorithm based design is demonstrated and validated by employing the 16-elements DDE array of monopole antennas and the three-ring CCAA of dipole elements.

In depth mathematical-analysis and experimentation of high-power SiC-FET based single-stage three-phase differential-based flyback inverter with practical design issues for grid-tied applications

This paper presents a detailed mathematical loss-modelling, design, hardware implementation issues, and experimental verification of high-power isolated single-stage three-phase differential-based flyback inverter (DBFI) for grid-tied photovoltaic applications. In addition, this paper studies the loss-modelling analysis of the DBFI components in terms of time and system parameters, which describes the power loss distribution over the circuit components for efficiency enhancement possibility. Also, it studies the practical design issues of DBFI; power stage design, HFT-based F3CC Nano-Crystalline C-Core design, passive elements selection effects on harmonics compensation of grid current waveforms, and the input DC current ripple for PV applications propriety. In addition, the input DC-voltage variation impact on the grid-current THD, system efficiency, and operational power factor are investigated. Also, continuous modulation scheme (CMS) is used to control the proposed DBFI for low-order harmonic components mitigation. The system is simulated by PSIM computer-aided simulator. Then, the proposed system is verified experimentally using a laboratory prototype controlled by TMS320C6713 DSP controller.

A Survey on Channel Estimation and Practical Passive Beamforming Design for Intelligent Reflecting Surface Aided Wireless Communications

Intelligent reflecting surface (IRS) has emerged as a key enabling technology to realize smart and reconfigurable radio environment for wireless communications, by digitally controlling the signal reflection via a large number of passive reflecting elements in real time. Different from conventional wireless communication techniques that only adapt to but have no or limited control over dynamic wireless channels, IRS provides a new and cost-effective means to combat the wireless channel impairments in a proactive manner. However, despite its great potential, IRS faces new and unique challenges in its efficient integration into wireless communication systems, especially its channel estimation and passive beamforming design under various practical hardware constraints. In this paper, we provide a comprehensive survey on the up-to-date research in IRS-aided wireless communications, with an emphasis on the promising solutions to tackle practical design issues. Furthermore, we discuss new and emerging IRS architectures and applications as well as their practical design problems to motivate future research.

A Review on Multi-Criteria Decision-Making and Its Application

Capable of Multi-Scale Decision Making (MCDM), it improves all areas of decision-making engineering from design production, but is also highly applicable to applications in high-tech market areas. Very small gains in material performance. The full potential of MCDM systems is realized by performance, while complex material selection considers the material, process and form of the problems. Therefore, it is necessary to expand the range of MCDM methods to conceptualize experience in developing a wide range of engineering applications and material selection. It is important to deal with and deal with uncertainty in order to effectively address current practical design issues and data controls, as well as product selection and effective application of MCDM. Design. Products with highly advanced materials and designed properties, especially composites and so on Functional materials are a significant part of starting to use MCDM. With the current emphasis on material design and modeling, it is desirable to incorporate a wide range of analytical capabilities into future versions of computer simulation software.

Introduction to Plastics Engineering

Abstract Industrial and consumer products made of plastics are ubiquitous in our daily lives. Converting raw plastics into useful parts is a scientific and technological challenge that has been progressively overcome in the past several decades. This expansive monograph authored by one of the leading experts with vast experience as an academic at IIT-Kanpur and a practitioner while at GE Corporate R&amp;D tackles this huge subject by expounding aspects of transforming modern plastics into useful day-to-day items based on principles of mechanical engineering and engineering mechanics. It weaves together complex issues related to the mechanics, mechanical design, fabrication, and assembly of engineered plastics. In doing so, the book distinguishes itself from others by emphasizing not just the material science and ‘build-and-test’ approach embraced by the plastics industry, but by adopting approaches from engineering science and materials science synergistically to address practical issues of part design, size, cost, development cycle, and assembly, among others.

Вопросы проектирования построек для экопарков в России

The paper considers a phenomenon that is becoming more and more entrenched in Russian society, namely, the desire for suburban life. For this paper, it does not mean the traditional cottage development in its different forms. On the contrary, it considers the creation of eco-parks, eco-villages and eco-tourism centers, which have recently started to appear across Russia. Presented research is at an early stage and has a clear interdisciplinary character. It is at the intersection of sociology, history, culture, architecture, construction technology, engineering trends and environmental design. The article identifies some promising directions of Russian and Western European architectural, technical, and figurative-symbolic trends in addressing practical design issues, based on historical and cultural studies in different countries. The author specifically notes wood as the most rational and at the same time traditional material for the construction of load-bearing and enclosing structures, as well as decorative and symbolic elements. But this practice will likely lead to similar and already existing scenarios. But at the same time, international experience in this area shows various innovative ways of creating volumes of buildings for suburban eco-life temporarily or permanently. The paper questions the architectural forms and technologies to be developed across Russia and its dependence on the specific place in terms of history and the surrounding landscape. It is proposed to study the problem in depth to identify useful historical and theoretical aspects and constructive and technical means, which will help to develop a methodology for creating visually harmonious, aesthetically acceptable and rational options for the realization of countryside buildings and complexes on the territory of ecovillages, natural tourist centers and eco-parks.

Co-Registration of Eye Movements and Fixation—Related Potentials in Natural Reading: Practical Issues of Experimental Design and Data Analysis

A growing number of studies are using co-registration of eye movement (EM) and fixation-related potential (FRP) measures to investigate reading. However, the number of co-registration experiments remains small when compared to the number of studies in the literature conducted with EMs and event-related potentials (ERPs) alone. One reason for this is the complexity of the experimental design and data analyses. The present paper is designed to support researchers who might have expertise in conducting reading experiments with EM or ERP techniques and are wishing to take their first steps towards co-registration research. The objective of this paper is threefold. First, to provide an overview of the issues that such researchers would face. Second, to provide a critical overview of the methodological approaches available to date to deal with these issues. Third, to offer an example pipeline and a full set of scripts for data preprocessing that may be adopted and adapted for one’s own needs. The data preprocessing steps are based on EM data parsing via Data Viewer (SR Research), and the provided scripts are written in Matlab and R. Ultimately, with this paper we hope to encourage other researchers to run co-registration experiments to study reading and human cognition more generally.

Practical Design of Electronic Emergency Stop Devices for Machine Safety

A variety of safety protective devices (SPDs) are currently available on the machinery safety market. SPD complexity and cost depend on the safety feature implemented as required for a specific piece of machinery in its working environment. However, one type of inexpensive SPD is mandatory for many types of machines: the emergency stop device (ESD). This paper introduces a novel ESD recently developed by the authors. This electronic ESD is capable of automatically performing emergency stop actions as commanded by a suitable external supervisory safety system connected to it, which may replace or reinforce the human action expected for the provision of safety. In addition, the device allows integration with any emergency stop circuit already designed for machinery by means of configurable features. Both practical design and implementation issues are discussed in detail through a fully exemplified concept-design-prototype-validation procedure.

Preparation of a radiology department in an Italian hospital dedicated to COVID-19 patients.

Preparedness for the ongoing coronavirus disease 2019 (COVID-19) and its spread in Italy called for setting up of adequately equipped and dedicated health facilities to manage sick patients while protecting healthcare workers, uninfected patients, and the community. In our country, in a short time span, the demand for critical care beds exceeded supply. A new sequestered hospital completely dedicated to intensive care (IC) for isolated COVID-19 patients needed to be designed, constructed, and deployed. Along with this new initiative, the new concept of “Pandemic Radiology Unit” was implemented as a practical solution to the emerging crisis, born out of a critical and urgent acute need. The present article describes logistics, planning, and practical design issues for such a pandemic radiology and critical care unit (e.g., space, infection control, safety of healthcare workers, etc.) adopted in the IC Hospital Unit for the care and management of COVID-19 patients.

An Optimal Radiation Pattern Synthesis and Correction of Mutually Coupled Circular Dipole Antenna Array

Abstract – This paper proposes a fundamental approach for radiation pattern correction of the mutually coupled circular dipole antenna array (CDAA) using parametric assimilation technique. The effect of mutual coupling is an indispensable part of any practical design issue of the antenna array. Many analytical and numerical techniques have been put forward in the past few decades for the calculation, compensation and reduction of mutual coupling effect. This paper shows an accurate method for mutual coupling correction by using a recently proposed technique called parametric assimilation technique, where the values of mutual impedance are calculated and assimilated with the values of the desired radiation pattern. The proposed technique is cost-effective, less complicated and easy to implement while achieves better performance for mutually coupled circular dipole antenna array synthesis. Grey Wolf Optimization (GWO) algorithm is a state-of-the-art stochastic algorithm applied here to find the optimal values of the current excitation weights and the inter-element spacing between each element of the CDAA for the desired, uncorrected and corrected far-field radiation pattern synthesis. PSO and DE optimization-based statistical results are also reported to compare the results obtained by using GWO algorithm to confirm the outstanding performance of GWO algorithm based design.

Design of DC‐side fault current limiter for MMC‐HVDC systems: Safety of the MMC along with frequency stability

A high voltage direct current system based on the modular multi-level converter (MMC-HVDC) is introduced as a suitable device for transmission of bulk powers over long distances. A pole-to-pole DC-side fault is a significant challenge for the MMC-HVDC system. Three main problems are the appearance of voltage spikes following a fast DC fault current break up, frequency instability due to insufficient inertia (networks such as renewable energy-based systems) and destruction of anti-parallel diodes within the MMC due to the high fault current. This study proposes a novel method for limiting DC fault current, improving isolation of the three-phase AC system from the DC-side. The suggested design employs high power resistors as virtual load such that continuity in active power flow will be kept on. Further, this prevents frequency deviation from exceeding the allowable limits. Also, transient over-voltages will be limited which are coming from stray inductances linked with electromagnetic effects of fault current level. Simulations and design practical issues have verified the validity of the proposal by using MATLAB/Simulink.