Conventional Transport Research Articles

Identification of Local Overpotentials and Their Spatial Distributions in Polymer Electrolyte Water Electrolyzers

Polymer electrolyte water electrolyzers (PEWEs) are pivotal in the transition to a clean energy economy, promising green and efficient hydrogen production. Understanding the complexities of overpotentials within PEWEs is crucial for optimizing their performance and efficiency1. For PEWEs to attain the highest possible system efficiency, considering a specific material set and operating parameters, meticulous design is imperative. The goal is to achieve a high reaction rate that is not only optimal but also uniform across the entire active surface area of the electrodes. This uniformity should ideally be maintained with minimal sensitivity to variations in operating conditions.This study focuses on the contribution of different overpotential categories and reveals their spatial variations through in-situ analysis to understand and overcome the issues caused by non-uniformity in reaction. Employing a segmented cell and printed circuit board (PCB) approach2, current density distribution (CDD) and distributed area-specific resistance (DASR) measurements are obtained, enabling a detailed examination of the mass transport overpotentials (as shown in Figure 1). Typically, in the fuel cell community, modeling mass transport limitations is thought of as diffusion-limited transport3. In the anode porous transport layer (PTL), oxygen accumulation (i.e. product transport limitation) can cause membrane dry-out and an increase in ASR4. The experimental results elucidate the intricate relationship between ohmic and mass transport losses, emphasizing the deep coupling induced by the two-phase nature of the system. Figure 1 shows that, as mass transport limitation grows, the highest increase in overpotential comes from mass transport-coupled ohmic losses. Beyond conventional diffusion limited mass transport losses, bubble dynamics significantly impact local hydration and ASR, highlighting the need for a holistic approach in device optimization5.This research contributes to the understanding of PEWE dynamics, providing a basis for informed engineering decisions. By unraveling the intricate interdependencies between overpotentials, this work empowers the efficient utilization of expensive catalyst materials. Moreover, it offers insights into mitigating the challenges associated with bubble removal, accomplishing this with lower pumping requirements that scale non-linearly. These insights enrich both theoretical understanding and are paramount for enhancing system efficiency and economic viability of PEWEs, thereby advancing the prospect of sustainable hydrogen production. Reference N. Danilovic and I. Zenyuk, Electrochem. Soc. Interface, 30 (2021).F. H. Roenning, A. Roy, D. S. Aaron, and M. M. Mench, J. Power Sources, 542, 231749 (2022) https://linkinghub.elsevier.com/retrieve/pii/S037877532200742X.A. Z. Weber et al., J. Electrochem. Soc., 161, F1254–F1299 (2014) https://iopscience.iop.org/article/10.1149/2.0751412jes.C. Immerz, B. Bensmann, P. Trinke, M. Suermann, and R. Hanke-Rauschenbach, J. Electrochem. Soc., 165, F1292–F1299 (2018).P. Satjaritanun et al., iScience, 23, 101783 (2020) https://doi.org/10.1016/j.isci.2020.101783. Figure 1

Advanced Mathematical Model for the Transport of Aggregating Nanoparticles in Water Saturated Porous Media: Nonlinear Attachment and Particle Size‐Dependent Dispersion

AbstractA conceptual mathematical model was developed to describe the migration of aggregating nanoparticles in water saturated, homogeneous porous media with one‐dimensional uniform flow. Nanoparticles can be found suspended in the aqueous phase or attached reversibly and/or irreversibly onto the solid matrix. The Smoluchowski population balance equation (PBE) was used to model the process of particle aggregation and was coupled with the advection‐dispersion‐attachment equation to form a nonlinear transport model. Furthermore, an efficient and accurate solver for the PBE, and an iterative solver for the linear or nonlinear attachment equations were employed. The new numerical model was applied to nanoparticle transport experimental data available in the literature. Although, conventional transport models can be used to describe nanoparticle migration at low ionic strength conditions, such models might not be applicable for high ionic strength conditions, where aggregation becomes a dominant process. Aggregation is significantly affecting the transport characteristics of nanoparticles. Under high ionic strength conditions, the mass retention in the solid matrix of the porous medium increases, and a nonlinear particle attachment behavior may be observed. The proposed model performed remarkably well, successfully capturing numerous physical processes associated with nanoparticle transport, including particle‐size‐dependent dispersion. Ignoring the aggregation process and using conventional colloidal transport models to model nanoparticle transport may lead to erroneous results.

The Extended Diamond Difference - Constant Nodal Method with Decoupled Cell Iteration Scheme in Two-Dimensional Discrete Ordinate Transport Problems

Analytical solutions for the Boltzmann transport equation are typically limited to specific scenarios, prompting the research transport community to extensively explore numerical approaches with special attention to the discrete ordinates (SN) formulation. The spectral nodal methods are widely recognized for their capability to preserve the analytical solution of the SN mathematical model. However, these formulations exhibit notable complexity with high-order polynomial approximations for the transverse leakage terms, motivating researchers to pursue simpler hybrid approaches by partially preserving the analytical solution. Both spectral nodal and hybrid spectral nodal methods introduce nonstandard auxiliary equations not amenable to standard iterative schemes due to a highly coupling in angular directions. Following these ideas, we present a finite element – spectral nodal hybrid method referred to as Extended Diamond Difference-Constant Nodal (EDD-CN) method for two-dimensional fixed-source discrete ordinate transport problems with constant nodal approximation for the leakage terms. The proposed method seeks to preserve eigenfunctions associated with the dominant pair of eigenvalues in the transverse integrated SN equations. In addition, we propose a novel iterative scheme called Decoupled Cell Iteration (DCI) scheme which decouples the angular directions in the nonstandard auxiliary equations and follows conventional iteration transport sweeps for solving SN problems.

The transition between the collision-dominated and ballistic electron transport regimes as the device length is reduced: A continuum analysis

Noting that the conventional collision-dominated electron transport perspective is only relevant when the length scale over which the transit occurs is greater than the electron’s mean free path, one can conceptually partition the electron transport “space” into collision-dominated and ballistic electron transport regimes. As the boundaries between these regimes are quite porous, in this analysis, we devise a means of quantitatively examining the transition between electron transport regimes as the length scale is reduced on a continuum basis. Our approach introduces a collision-dominated fractional scattering parameter, this parameter quantifying the fraction of the total scattering rate that arises purely from bulk scattering processes, contact scattering also contributing to the total scattering rate. We pursue this analysis for two conventional semiconductors of interest, silicon and gallium arsenide. A determination of the dependence of the results on both the length scale and the crystal temperature is pursued. Finally, for the specific case of room temperature, a comparison with the results of experiment is performed.

Asymptotic analysis of MHD chemically reacting boundary layer flow of Jeffrey hybrid nanofluid

AbstractFluids with enhanced heat transport characteristics are essential for efficient convection heat transportation. Hybrid nanofluids have demonstrated their effectiveness as viable substitutes for conventional heat transport fluids. This study explores the heat and mass exchange occurring within a chemically reactive, unsteady boundary layer flow of a copper oxide‐multi‐walled carbon nanotubes (CuO‐MWCNTs)/ethylene glycol Jeffrey hybrid nanofluid. Additionally, the influence of heat source/sink effects in a hydromagnetic environment is carefully added. The study employs a non‐Newtonian flow model and incorporates the Arrhenius activation energy for analysis. The hybrid nanofluid consists of a base fluid, ethylene glycol, enriched with copper oxide nanoparticles and multi‐walled carbon nanotubes. The governing coupled non‐linear partial differential equations are transformed into ordinary differential equations using similarity transformations, considering appropriate free stream, and wall boundary conditions; then, the Shooting method is employed to solve the resulting ordinary differential equations (ODEs) in MATLAB. The graphical and numerical outcomes are studied for various parameter combinations. The graphs illustrate the numerical results for the CuO‐MWCNTs/ethylene glycol hybrid nanofluid. These results are comprehensively discussed to analyze the influence of different thermo‐fluidic parameters on the Jeffrey hybrid nanofluid's heat, mass, and flow characteristics. The skin friction, Nusselt number, and Sherwood number are provided in a numerical table that displays the alterations of these parameters across various parameter values. As the Jeffrey fluid parameter rises, the Nusselt number and skin friction escalate, while the Sherwood number diminishes. Conversely, as the Deborah number rises, the Nusselt number and skin friction decline, but the Sherwood number increases. A comparative analysis with published results confirms the consistency of the present results.

Spin Gapless Quantum Materials and Devices.

Quantum materials, with nontrivial quantum phenomena and mechanisms, promise efficient quantum technologies with enhanced functionalities. Quantum technology is held back because a gap between fundamental science and its implementation is not fully understood yet. In order to capitalize the quantum advantage, a new perspective is required to figureout and close this gap. In this review, spin gapless quantum materials, featured by fully spin-polarized bands and the electron/hole transport, are discussed from the perspective of fundamental understanding and device applications. Spin gapless quantum materials can be simulated by minimal two-band models and could help to understand band structure engineering in various topological quantum materials discovered so far. It is explicitly highlighted that various types of spin gapless band dispersion are fundamental ingredients to understand quantum anomalous Hall effect. Based on conventional transport in the bulk and topological transport on the boundaries, various spintronic device aspects of spin gapless quantum materials as well as their advantages in different models for topological field effect transistors arereviewed.

Bone Transport through Induced Membrane Technique versus Conventional Bone Transport Technique in Management of Bone Defects of Lower Limbs

Abstract Objectives To assess whether Bone transport through induced membrane (BTM) has better outcomes regarding docking site union and infection recurrence than conventional bone transport (BT) or not in the treatment of infected lower limb long bones defects. Methods A prospective randomized controlled study in a single institution was conducted. A total of 30 patients with infected non united fractures of long bones of lower limbs were divided into 15 patients (10 femurs, 5 tibias) treated by BTM and 15 patients (3 femurs,12 tibias) treated by BT. The outcome measures includes external fixation time (EFT), external fixation index (EFI), docking time (DT), bone and functional outcomes evaluated by the Association for the Study and Application of the Method of Ilizarov (ASAMI) scoring system, postoperative complications evaluated by Paley classification and number of additional operations. Results The mean docking time (DT) was significantly lower in BTM group in comparison to BT group (3.67 ± 0.82 months vs 4.80 ± 0.86 months respectively) (p value 0.001). Docking site nonunion and infection recurrence were significantly lower in BTM group in comparison to BT group (0% vs 40% respectively) (p value 0.02) and (0% vs 33.3% respectively) (p value 0.04). Mean number of additional operations per patient was significantly lower in BTM group in comparison to BT group (0 vs 0.80 ± 1.08 operations respectively) (p value 0.01) Conclusion Both BTM and BT achieved satisfactory postoperative bone and functional outcomes in patients with infected long bones defects of lower limbs, while BTM had significantly faster docking site union, lower incidence of postoperative complications including docking site nonunion and infection recurrence rates and lower number of additional operations needed at the expense of 2 staged procedure in comparison to BT.

Innovations in daily commuting - what types of solutions are competitive? European case study.

Innovations drive dynamic changes in daily commuting especially in functional urban areas (FUAs), where transport systems are developed. Innovative solutions are being tested in FUAs, and they not only pose an alternative to conventional transport systems, but can also revolutionize daily commuting in cities. The main aim was to classify the innovation drivers identified in literature and to determine their impact on travel behaviour (TB) in FUAs with a use of expert survey. The following research hypothesis was examined: the level of innovation utilization in daily commuting and its impact on TB is similar in countries with similar levels of economic development. The survey results were processed to (1) create a ranking of innovations in TB in European OECD countries and (2) group countries based on similarity in prioritizing innovations influencing TB, using Ward hierarchical clustering method. As a result, innovative factors were comprehensively identified and classified in six categories.

Motorcycle Taxi in Shared Mobility and Informal Transportation: A Bibliometric Analysis

Background: Motorcycle taxi (MCT) is a form of widely used informal transportation. Over the last few years, MCT has developed from conventional public transportation into a modern business using digital technology. In these services, digitalization has received a positive response from the public and the increasing number creates many challenges. However, there is a gap in the discussion of new service models for shared mobility transportation. Objective: This research aimed to analyze MCT, providing an overview of the services as informal transportation. Methods: Bibliometric analysis was used to evaluate 366 articles published in the Scopus database between 2011-2023. In addition, annual publications and citation topics, most productive sources and influential articles, relevant affiliations, productive countries, location research, main topics, and future research options were identified. Results: Frequently occurring topics were reported with past and present academic developments related to MCT services. Based on the publication themes, the main topics were arranged into five clusters, namely (a) the development of more sustainable transportation services, (b) environmental and health impact, (c) road safety, (d) risky behaviors or risk factors as MCT drivers, and (e) utilization of MCT for medical or health services. Meanwhile, the research topics comprised themes about travel behavior, health, safety-security, customer satisfaction, and advanced mobility topics. Conclusion: This research increased knowledge about main topics, trends and future analysis options in MCT. The academic developments served as a guide to future topics. Keywords: Motorcycle taxi, public transportation, informal transportation, shared mobility, bibliometric analysis

Enhancing Healthcare Access: Drone-based Delivery of Medicines and Vaccines in hard-to-Reach Terrains of Northeastern India

Background: Ensuring efficient healthcare access in a geographically diverse country like India poses significant challenges, particularly in challenging terrains. Conventional transportation methods often encounter difficulties due to inadequate infrastructure and adverse climatic conditions, resulting in delays in medical supplies. This study aimed to assess the viability of drones for transporting various types of medical supplies across diverse geographical landscapes, also evaluating their impact on transportation time, covered distance, weight carrying capacities and safety of medical supplies. Materials and Methods: The study spanned 4 months across 19 healthcare centres across Manipur and Nagaland. Different types of drones were used for the transportation of vaccines, medications and surgical items across these centres covering terrains such as flatlands, valleys, foothills, islands and hills. Results: Drones were able to successfully transport the medical supplies maintaining the essential temperatures and integrity of the samples. Further, drone-based supplies significantly reduce the delivery time compared to conventional road-based delivery mechanisms. Conclusion: The present study demonstrates the potential application of drones for the delivery of healthcare supplies in remote areas. Despite the logistical challenges, drones offer a time-efficient alternative for medical supply delivery. However, there is a need for further research and logistical infrastructure development in the current field.

Surviving at a Falling Transportation Industry with the Help of Emotional Relationship with your Customers

Introduction Public intercity transportation is an example of a rapidly evolving industry. In developing countries, we observe the increasing popularity of airlines, whereas bus lines start to lose their significance. Methods The successive bankruptcy of bus companies, which have made a large amount of investment and provided significant employment, is a case worth examining. This article offers a case study from the Turkish public intercity transportation industry in which a bus company distinguishes itself by becoming a love brand with the relationship it establishes with its customers. The case shows that the emotional relationship established during the ups and downs of sectors have become insurance that protects companies during the downturn. Results To support our argument, we estimated the occupancy rates of bus companies based on characteristics such as ticket price, travel time, existence of catering service, social media interaction, and year of establishment. We found that the significant variables explaining occupancy rates are the companies' founding year and positive social media interaction frequency. Conclusion In an estimation where even the price is not a significant variable at the 0.01 level, the significance of the above-mentioned variables shows that relationship-based dynamics can be important demand determinants in a conventional transportation sector.

Feasibility Analysis of Solar Energy and Role of Lithium-Ion Battery Reserved in Electric Vehicle Market: A Path Towards Green Transportation

Solar-based vehicular electrification is bound to play a vital role in Green House Gas (GHG) emission reduction from conventional transports and supporting the fight against environmental degradation. This paper presents the feasibility of solar-based electric vehicle charging (SEVC) in India, a shift of the transportation sector to renewable energy implementation. Solar-electric vehicles may transform the scenario in the coming future in India on a larger scale. Extensive negative environmental impact is produced by transport activities as it pours out 14% of global GHG emissions. The transportation sector is the second major contributor to pollution in India. Currently, dealers of non-renewable resources like coal, petroleum, etc. are facing a tough time meeting increasing demand. This results in limited resources which are being suppressed by the dealers and producers to meet this need which leads us to an insecure future, having scarcity of minerals and fuel. In this paper, we perform a graphical analysis of fuel consumption in India, the growing demand for green transportation in the Indian market and solar potential in our country. In Feb 2023, India’s government revealed the finding of a 5.9 million tons stockpile of unexplored lithium deposits in the Jammu and Kashmir state. So, the price of batteries would be significantly impacted by this, making EVs more accessible to customers. This paper also includes challenges in adopting solar-based transportation, steps of the Indian Government towards green transportation and recommended policies.

A mobility pilot development process experimented through a MaaS pilot in Budapest

Recently, several new concepts and innovative technologies have emerged to overcome the problems of urbanization, which can be hardly solved with using exclusively private vehicles or conventional public transport services. One of the new solutions is the Mobility-as-a-Service (MaaS) concept, a user-centric mobility distribution scheme, in which the user needs are satisfied via a single platform, and multiple transport options are offered by one MaaS operator (MO). In the last years, a couple of MaaS pilots were performed, but previous papers fail to focus on the pilot development and the proper description of the minimum viable product. A pilot of MaaS in Budapest has been developed by using the innovative Scrum methodology successfully involving six mobility service providers, such as public transport, shared mobility, and taxi, in the live demonstration. Current article provides detailed information about the pilot development including technical, legal, and business use cases for all service providers. The results of the recruitment and the characterization of the early-bird users are presented, too. The iterative pilot development process can be utilized by those MOs and governmental organizations that would like to initiate a new mobility project based on the MaaS concept.

Enhanced efficiency of bifacial perovskite solar cells using computational study

The most rapidly expanding type of solar cells are the Perovskite Solar Cells (PSCs), because of its high device performance, ease of synthesis, high open-circuit voltage, and affordability. Despite these advantages, the development of perovskite-based solar cells continues to be impeded by the issues with perovskite stability and the utilization of the hazardous heavy element lead (Pb). The study emphasizes on the bifacial structure that maintains the conventional absorber layer and electron transport layer (ETL) in the optimized PSC structure. This study employs SCAPS software for device simulation to comprehensively analyze how various parameters affect the performance of solar cells. Additionally, doping concentration variation in both ETL and HTL are explored. The simulation reveals that changing device structure from monofacial to bifacial significantly influences PSC performance, demonstrating that optimizing individual layers effectively enhances overall solar cell performance. The optimized structure achieves impressive PSC performance metrics through parametric analysis, such as voltage (VOC) of 1.18 V, fill factor (FF) of 82.24%, current density (JSC) of 27.12 mA/cm2, power conversion efficiency (PCE) of 27.90% for an incident solar spectrum from the ETL side, and power conversion efficiency (PCE) of 19.86% for an incident solar spectrum from the HTL side, the calculated bifaciality factor (BF) for this structure is 71.18%.

Electricity in Public Passengers’ Transportation and the Impact on Consumption in the National Energy System

Abstract Electric drive systems in mobility solutions are increasingly being used by the manufacturers in the global automotive industry. The European strategy to reduce greenhouse gas emissions to zero by 2050 is also transposed into Romania’s Energy Strategy. An important part of this strategy is the use of electricity in public passenger transport to significantly reduce pollution in urban areas. The rapid pace in terms of the renewal of conventional urban transport with modern electrified solutions requires, at the same time, an analysis of the pressure that this new consumer can exert on the national energy system.

Routes with roots: Pedestrian route choices and sense of place of an urban university community

Understanding how people choose routes in urban environments is essential for effective urban planning. While conventional transportation studies focus on utilitarian decision-making, this research investigates the complex interplay between human-environment interactions and emotional attachments to places, which influence transportation choices. Specifically, we examine the impact of sense of place in pedestrian route choice within a densely populated urban university community. Unlike typical urban settings characterized by clear roads and landmarks, university environments often feature intricate layouts with diffuse pathways, shared spaces, and a lack of clear spatial hierarchies. This complexity challenges conventional spatial knowledge acquisition methods. Individuals navigating such environments tend to rely on socio-sensory wayfinding strategies, developing emotional connections to specific places and routes over time. Consequently, route choices in these contexts may not always be deliberate but rather subconscious and nuanced. Our study focuses on elucidating the impact of the sense of place—a composite of conscious and subconscious perceptions, emotions, and attachments to a location—on daily route decisions. Through structural equation modeling (SEM) analysis, we demonstrate that the sense of place significantly influences route choices within community building complexes, surpassing utilitarian considerations as a primary explanatory factor. These findings underscore the importance of emotional and psychological factors in shaping urban route decisions, offering valuable insights for urban planning and management strategies.

Design and development of grid independent integrated energy system for electric vehicle charging stations at different locations in Malaysia

Electric vehicles (EVs) have revolutionized the transportation sector as an alternative to conventional fossil fuel-based transportation. It becomes more effective when the charging energy comes from green, renewable, cost-effective, eco-friendly resources. The present work discusses modelling a hybrid renewable energy system for EV charging stations in Malaysia. This work presents techno-economic investigation for different hybrid energy system arrangements of solar photovoltaic (PV), wind turbine (WT), natural gas generator (GS) and battery energy storage (BES) for EV charging station. The EV load demand is calculated based on the transportation fleet of an institution considered for five different climatic locations in Malaysia using HOMER-Pro software. Considering the technical sizing of the hybrid system, the minimization of the energy system and net present cost are discussed for each locations. The optimization study of hybrid energy systems is further examined for social benefits and environmental analysis by including the human development and employment creation index. The comparative analysis of hybrid energy storage systems is performed separately. This study uses sensitivity analysis to elaborate on the cost-effectiveness and technical feasibility of the hybrid system, considering the cost of system components, macroeconomics parameters, and load variation. The finalized results indicate that the solar PV-BES-GS12 hybrid energy system is the most suitable combination for the integrated grid-independent EV charging station operation at each locations.

Simultaneous Li-Doping and Formation of SnO2-Based Composites with TiO2: Applications for Perovskite Solar Cells.

Tin oxide (SnO2) has been recognized as one of the beneficial components in the electron transport layer (ETL) of lead-halide perovskite solar cells (PSCs) due to its high electron mobility. The SnO2-based thin film serves for electron extraction and transport in the device, induced by light absorption at the perovskite layer. The focus of this paper is on the heat treatment of a nanoaggregate layer of single-nanometer-scale SnO2 particles in combination with another metal-dopant precursor to develop a new process for ETL in PSCs. The combined precursor solution of Li chloride and titanium(IV) isopropoxide (TTIP) was deposited onto the SnO2 layer. We varied the heat treatment conditions of the spin-coated films comprising double layers, i.e., an Li/TTIP precursor layer and SnO2 nanoparticle layer, to understand the effects of nanoparticle interconnection via sintering and the mixing ratio of the Li-dopant on the photovoltaic performance. X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HR-TEM) measurements of the sintered nanoparticles suggested that an Li-doped solid solution of SnO2 with a small amount of TiO2 nanoparticles formed via heating. Interestingly, the bandgap of the Li-doped ETL samples was estimated to be 3.45 eV, indicating a narrower bandgap as compared to that of pure SnO2. This observation also supported the formation of an SnO2/TiO2 solid solution in the ETL. The utilization of such a nanoparticulate SnO2 film in combination with an Li/TTIP precursor could offer a new approach as an alternative to conventional SnO2 electron transport layers for optimizing the performance of lead-halide perovskite solar cells.

Feasibility analysis of solar electric vehicles

Feasibility analysis of solar electric vehicles

Study of Activation Energy for Viscous Flow of Mixtures as a Measure of Dilution Efficiency for Heavy Oil-Diluent Systems

As the demand for crude oil continues to increase in response to the continued global needs for it, the development of unconventional crude oil reserves is the only way to sustain global supply. However, the excessively higher viscosity of heavy crude oil makes it less attractive for conventional pipeline transportation. Therefore, reducing the viscosity of heavy crude oil to meet crude oil transporting pipeline regulations is a necessity. This paper has assessed the dilution efficiency of well-known diluents in the petroleum industry, using different dilution ratios based on a thermodynamic approach involving activation energy and heat of vaporization determination. Based on selected dilution ratios, kinematic viscosities of binary and ternary systems of toluene and natural gas condensate as diluents, and Saudi Heavy crude oil as the base oil were measured, using anticipated field based temperatures reported in the literature, which facilitated the experimental approach. The study shows that although the ternary systems have the lowest activation energy for viscous flow and heat of vaporization in accordance with the thermal activation theory of viscous flow, natural gas condensate binary systems have the lowest cost of transportation per barrel of total fluid in the transporting pipeline. The study further shows that the binary systems for toluene and Saudi Heavy crude oil have higher activation energy for viscous flowed compared to the toluene systems.