Access Distance Research Articles

Gateway Placement in Integrated Satellite–Terrestrial Networks: Supporting Communications and Internet of Remote Things

Low Earth orbit (LEO) satellite constellations have become a promising architecture to integrate with terrestrial networks for facilitating communications and Internet of Remote Things (IoRT) services through gateways. Nevertheless, different gateway locations may have various channel conditions and service demands due to differentiated atmospheric conditions, populations, and number of terminal devices required by IoRT services in different areas. Besides, the gateway placement scheme further affects the service coverage performance and the access performance of the network to service demands. Therefore, gateway placement plays a pivotal role in improving network capabilities in the integrated system of LEO satellites and terrestrial networks (ISoLS-TNs). Motivated by the aforementioned facts, in this article, we first formulate the gateway placement problem in ISoLS-TNs as a multiobjective optimization problem to maximize the total revenue of service data demand within coverage while minimizing the average access distance and the number of deployed gateways. In order to enhance network resource utilization and assure local information confidentiality, a distributed resource allocation (DRA) mechanism based on the alternating direction method of multipliers (ADMMs) algorithm is designed to calculate the total revenue of service data demand within coverage. Furthermore, we propose a genetic-based gateway placement algorithm with the ADMM for DRA. Finally, through massive simulations based on real data, we validate the effectiveness of the proposed algorithm in improving resource utilization and coverage performance of the network. In addition, the results also bring lights on the relationship between service data demand distribution and gateway location preference.

Measuring Access and Egress Distance and Catchment Area of Multiple Feeding Modes for Metro Transferring Using Survey Data

Multiple feeding modes, including walking, bus, private bike, docked bike-sharing, private electric bike (e-bike), car, and taxi, are applied for better accessibility in a metro-based trip. It is crucial to understand their access/egress distances and corresponding catchment areas of metro stations. This paper determines these two distances and accessible areas of stations for different feeding modes based on Nanjing Population Survey data and GIS data by using a network-based approach in Nanjing, China. Considering the distribution of access/egress distance, regression models are established for the exploration of the threshold of distance to delineate catchment areas. What is more, the spatio-temporal characteristics of multiple feeding modes are analyzed. The results indicate that the average feeding distance of walking is the shortest, but docked bike-sharing has the shortest average feeding time, about 8 min. The average feeding time of private e-bikes is close to that of the private bike, but the feeding distance of private e-bikes is about 1.3 times as long as that of private bikes. Moreover, the origin of an over-10 km transfer for accessing metro stations is usually far away from metro lines and the transferring station is mostly the terminal station. Generally, longer access distance means larger catchment area but the result is also influenced by the condition of street network. Moreover, catchment areas for the same feeding modes are different between urban and suburban areas.

Memory Space Recycling

Many program codes from different application domains process very large amounts of data, making their cache memory behavior critical for high performance. Most of the existing work targeting cache memory hierarchies focus on improving data access patterns, e.g., maximizing sequential accesses to program data structures via code and/or data layout restructuring strategies. Prior work has addressed this data locality optimization problem in the context of both single-core and multi-core systems. Another dimension of optimization, which can be as equally important/beneficial as improving data access pattern is to reduce the data volume (total number of addresses) accessed by the program code. Compared to data access pattern restructuring, this volume minimization problem has relatively taken much less attention. In this work, we focus on this volume minimization problem and address it in both single-core and multi-core execution scenarios. Specifically, we explore the idea of rewriting an application program code to reduce its "memory space footprint". The main idea behind this approach is to reuse/recycle, for a given data element, a memory location that has originally been assigned to another data element, provided that the lifetimes of these two data elements do not overlap with each other. A unique aspect is that it is "distance aware", i.e., in identifying the memory/cache locations to recycle it takes into account the physical distance between the location of the core and the memory/cache location to be recycled. We present a detailed experimental evaluation of our proposed memory space recycling strategy, using five different metrics: memory space consumption, network footprint, data access distance, cache miss rate, and execution time. The experimental results show that our proposed approach brings, respectively, 33.2%, 48.6%, 46.5%, 31.8%, and 27.9% average improvements in these metrics, in the case of single-threaded applications. With the multi-threaded versions of the same applications, the achieved improvements are 39.5%, 55.5%, 53.4%, 26.2%, and 22.2%, in the same order.

Geodiversity Supports Cultural Ecosystem Services: an Assessment Using Social Media

Geodiversity is under threat from both anthropogenic activities and environmental change which therefore requires active management in the form of geoconservation to minimise future damage. As research on the role of geodiversity on ecosystem service (ES) provision has been limited, there is a need to improve our understanding of which aspects are most important to providing ES to better inform approaches to its conservation. Here, we focus on the cultural ES of hiking in Wales, UK. Harnessing big data from the social media website Flickr, we used the locations of geotagged images of hiking and a range of spatial layers representing geodiversity, biodiversity and anthropogenic predictor variables in habitat suitability models. To gain a deeper understanding of the role of geodiversity in driving the distribution of this cultural service, we estimated the strength and nature of the relationship of each geodiversity, biodiversity and anthropogenic indicator with hiking. Our models show that three geodiversity (distance from coast, range in slope and range in elevation) and two anthropogenic (distance from greenspace access point and distance from road) variables were the most important drivers of hiking. Furthermore, we assessed the content of the images to understand which features of geodiversity people interact with while hiking. We found that people generally take images of geomorphological and hydrological features, such as mountains and lakes. Through understanding the geodiversity, biodiversity and anthropogenic drivers of hiking in Wales, as well as identifying the geodiversity features people interact with while hiking, this analysis can help to inform future geoconservation methods by focusing efforts on these important features.

Evaluating a Tobacco Treatment Program’s Transition to Telehealth Using a Social Determinants of Health Lens

IntroductionWhile strong associations exist between social determinants of health (SDOH), socioeconomic status, and smoking, these factors are not routinely assessed in tobacco treatment programs (TTP). This study addresses this gap by evaluating a composite metric of SDOH and a measure of access to care to determine program reach before and after the implementation of telehealth tobacco treatment delivery.Aims and MethodsWe examined inpatient data from a large TTP during two comparable time periods from April 1, 2019 to September 30, 2019 (pre-telehealth) and from April 1, 2020 to September 30, 2020 (telehealth). The populations were compared using point-of-care data, including 5-digit zip codes mapped to the CDC’s Social Vulnerability Index (SVI) and driving distance (in 60-min increments) to the study hospital. Chi-square tests for homogeneity were performed for SVI and driving distance comparisons.ResultsWhile distance distributions were significantly different between the pre-telehealth and telehealth populations (χ 2 = 13.5 (df = 3, N = 3234), p = .004, no significant differences existed in the proportion of SVI categories between the two populations (χ 2 = 5.8 (df = 3, N = 3234), p = .12). In the telehealth population, patients with the highest SVI vulnerability had the greatest proportions living >1 h from the hospital.ConclusionsThis study offers a novel evaluation of tobacco treatment in relation to an SDOH metric (SVI) and care access (distance to the hospital) for inpatient populations. Patient reach, including to those with high vulnerabilities, remained consistent in a transition to telehealth. These methods can inform future reach and engagement of patients who use tobacco products, including patients with high vulnerability or who reside at greater distances from treatment programs.ImplicationsThis study provides the first analysis of inpatient tobacco use treatment (TUT) transition to telehealth delivery of care during the COVID-19 pandemic using the CDC’s SVI metric and patient distance to the hospital. The transition resulted in consistent reach to patients at the highest vulnerability. These findings can inform efforts to evaluate SDOH measures and improve reach, engagement, and research on telehealth delivery of inpatient TUT.

A Hierarchical Modulation Enabled SNR Allocable Delta-Sigma Digital Mobile Fronthaul System

Internet of everything is being build up rapidly, which causes much higher requirements towards the flexibility of communication resources, especially the adaptivity of the fronthaul to various transmission distances and capacities. In this paper, we proposed a low-cost and spectrum efficient 5G fronthaul broadband connection solution that combines hierarchical modulation technology and delta-sigma modulation. The proposed scheme can double the number of accesses without occupying extra wavelengths. Moreover, such architecture can flexibly allocate the SNR of a group of remote radio units for different user requirement of transmission rate and reaches. Simulation results show that the proposed scheme can increase the access distance of the fronthaul network by 23% and the capacity by 16.7%. The feasibility of the solution is verified through a proof-of-concept experiment. After 20 km transmission, the OFDM-64QAM and -256QAM signal with a center frequency of 3.5 GHz and a bandwidth of 500 MHz can meet the EVM requirements of 8% and 3.5%, respectively. And when the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${R_{LM}}$</tex-math></inline-formula> of the hierarchical PAM4 signal is 0.6, the ROP required by the most-significant bit branch can be reduced by ∼1.5 dB.

Fuzzy-based GIS approach with new MCDM method for bike-sharing station site selection according to land-use types

Bike-Sharing Systems (BSSs) support urban mobility by strengthening the scope of public transport networks, which may be insufficient in smart cities. This paper aims to present a hybrid approach that includes a Fuzzy Logic (FL)-based Geographic Information System (GIS), the Analytic Hierarchy Process (AHP), the VIse Kriterijumska Optimizacija I Kompromisno Resenje (VIKOR) method, and the Psychometric-VIKOR method for the problem of the selection of BSS station sites depending on transportation and recreational land uses. The FL approach was included in the GIS analysis in order to characterize the uncertainty of a potential passenger's tendency to start a trip at a station within an accessible distance from the urban facilities. By combining fuzzy-based GIS analysis with the AHP method, a spatial analysis was performed for the deployment of BSS stations. The VIKOR and Psychometric-VIKOR methods were used to evaluate the performance of current and alternative locations of BSS station. This study is the first known application of the Psychometric-VIKOR method for the problem of the selection of BSS locations. The innovative hybrid approach can be used by authorities as a useful tool in solving decision-making problems that involve uncertainty in future urban investments.

The Station Location Problem of Public Bicycle Systems with the Demand Depending on Access Distance

The Station Location Problem of Public Bicycle Systems with the Demand Depending on Access Distance

Mode choice, substitution patterns and environmental impacts of shared and personal micro-mobility

Shared micro-mobility services are rapidly expanding yet little is known about travel behaviour. Understanding mode choice, in particular, is quintessential for incorporating micro-mobility into transport simulations in order to enable effective transport planning. We contribute by collecting a large dataset with matching GPS tracks, booking data and survey data for more than 500 travellers, and by estimating a first choice model between eight transport modes, including shared e-scooters, shared e-bikes, personal e-scooters and personal e-bikes. We find that trip distance, precipitation and access distance are fundamental to micro-mobility mode choice. Substitution patterns reveal that personal e-scooters and e-bikes emit less CO2 than the transport modes they replace, while shared e-scooters and e-bikes emit more CO2 than the transport modes they replace. Our results enable researchers and planners to test the effectiveness of policy interventions through transport simulations. Service providers can use our findings on access distances to optimize vehicle repositioning.

Providing accessible distance learning for students with disabilities in Saudi Arabia

After the COVID-19 outbreak, Saudi Arabia’s Ministry of Education transformed the education system from traditional learning to distance learning (DL). The aim of this study is to share the Saudi experience including plans, policies, and programs regarding the use of DL for students at various levels of education. This is the pioneer study from Saudi Arabia, which evaluates DL impact on special students and provides recommendations for such students regarding DL. The Saudi Ministry of Education released one of the most powerful and diverse electronic systems with fully interactive technology options through the following platforms: Madrasati School, the IEN National Education Portal, IEN educational television, and virtual kindergarten. The same platforms are accessible for students with disabilities and we have found that such students can equally benefit from them with some modifications. These modifications are on the individual needs of special students. This article presents the details of various tools and programs available for DL to students in Saudi Arabia. Furthermore, we have analyzed the suitability of these programs for special students in our discussion. Finally, we have made our recommendation and provided future directions to improve the DL experience for students with disabilities.

Formal and Non-formal Skills Improvement for the Marginalised Youth in Uganda

The aim of the article was to explore ways in which formal and non-formal skills development programmes can be improved for education continuity and employability of marginalised youth. This is attributed to the fact that coronavirus disease (COVID-19) with its related lockdowns is causing not only unprecedented disruption in the provision of skills, but also catalysed innovation in distance learning. A qualitative case study with some elements of action research, systematic inquiry and non-participant classroom observation with capability and empowerment theories supported the inquiries. Thematic analysis was used. Results reveal that while access to skills development was maintained in some spaces through a rapid shift to distance learning, the pre-existing social and digital divides deprived marginalized groups of continued learning and putting them behind schedule. Many institutions and learners lack operational distance-learning platforms, digital skills and devices. Save for the few exceptions, distance learning policies by the government have not yet been able to facilitate the acquisition of practical skills, which are critical components for the success of education and employability. Evidence points not only to pedagogical dimensions with educator’s incompetence to provide a supportive environment, but also to designing structured educational resources versus the abundance of online resources, disruptions to assessment and certification, and a general decline in the quality of practical training causing demotivation among learners and educators. The general increased economic hardship has also increased the likelihood of marginalised youth dropping out of education. The study recommends a robust shift on how skills are delivered-shift to digital literacy and adoption to technology, forge national and regional public private partnerships to increase the availability of accessible distance learning solutions, allocate more financial resources, develop new training programmes by marrying curricula to real life working situations, assess and certify online for educational continuity and employability.

FACTORS RELATING TO THE LEVEL OF PREGNANT WOMEN'S SATISFACTION USING ANC SERVICE

AbstractBackground: Independent Midwifery Practice is a health service provider that has a significant contribution in providing mother and child health services. One important indicator in service is satisfaction. There are still many pregnant women who are not satisfied with the ANC services provided. The purpose of the study was to analyze factors related to satisfaction of pregnant women in using ANC services. Method: Cross sectional, with purposive sampling technique. The number of samples were 89 pregnant women who visited PMB in August - September 2019. The independent variables were maternal characteristics (age, parity, education, occupation), service quality, service facilities, and access (financing and distance systems). The dependent variable was the level of satisfaction. Data analysis used Somers'd Test and contingency coefficients. Results: Factors related to satisfaction level were service quality, service facilities and financing system with a value of p&lt;α&lt; 0.05 and factors not related to satisfaction level were age, education, parity, occupation and distance with a value of p&gt;α&gt;0.05. Conclusion: Good service, good facilities and the financing system used tend to produce high levels of satisfaction.

Demonstration of flexible access in a rate-adaptive visible light communication system with constellation probabilistic shaping.

In this paper, we propose and experimentally demonstrate a distance-based rate-adaptive visible light communication (VLC) system based on constellation probabilistic shaping (PS) for a multiple-user access network. For users with different access distance, we optimize the transmission data rate close to the channel capacity by applying PS combined with code-rate adaptive FEC at the transmitter side according to the per-user signal-to-noise ratio (SNR) budget. This is also proved to be a convenient way to ensure fine granularity of information rate per user with wider flexibility compared with non-PS modulation formats. We also investigate the performances of different PS-QAM modulation formats under different SNR level when considering peak-to-average power ratio (PAPR) in the VLC system. Optimal PS-QAM and FEC code-rate are also studied in the flexible VLC access system. In addition, in order to overcome the nonlinear distortion in the system, a neural network (NN) is used as the post-equalization. Finally, we demonstrate the flexible access with the net data-rate from 1.84 to 3.37 Gbps for 20 and 1-meter distance, with a maximum 28% overall capacity improvement compared with regular non-PS modulations.

OPPORTUNITIES OF DISTANCE LEARNING AT THE MEDICAL UNIVERSITY

COVID-19 pandemic has led to changes in all areas of human activity, and they have not escaped the education system. One of the new and most highly effective and, especially relevant, areas of improvement in the educational process of higher education is the use of distance learning.&#x0D; The aim of the research: to analyze the opportunities, advantages and disadvantages of using distance learning at a medical university.&#x0D; Distance learning is a form of learning with the use of computer and telecommunication technologies, which provide interaction of teachers and students at different stages of learning and independent work with materials from the information network. There are a number of platforms and applications as tools for effective, interesting and interactive learning: Moodle, Google Classroom, Zoom, Skype, Google Hangouts, WebEx, MyOwnConference, Microsoft Teams.&#x0D; Distance learning includes a set of the following components: providing educational material to the student; means of monitoring student performance; student consultations by the program-teacher; means of interactive cooperation between teacher and student; the ability to quickly add new information to the course, error correction.&#x0D; Ivano-Frankivsk National Medical University uses Microsoft Teams as a tool for distance learning. Microsoft Teams is a state-of-the-art real-time video conferencing tool that integrates all Office 365 tools, gathers up to 300 participants, and holds meetings lasting up to 24 hours. Also, this service includes communication in general chat and personal messages, shared access to educational materials in various formats, access to the cloud environment, control of the level of knowledge can be carried out in the form of an oral interview and with the use of test tasks, sending files, it is possible to record video conferences, screen demonstrations, presentations, web pages, use the board.&#x0D; Distance learning has a number of advantages such as: flexibility, relevance, convenience, modularity, cost-effectiveness and the ability to simultaneously use a large amount of educational information for any number of students, interactivity, removing psychological barriers to communication, blurring borders, no direct contact between people, which allows to actively learn even during illness or self-isolation. However, despite these advantages, we should not forget about the disadvantages. Distance education requires a certain level of hardware and software. No matter how accessible computer distance education may seem, it requires the learner to have a computer and Internet access, which not everyone has. These also include: the need for a certain level of hardware and software, depersonalization of communication, negative impact on students' health, problems with mastering practical skills, lack of direct communication with patients, inability to participate in professors wardrounds, supervise patients. As for carrying out diagnostic procedures using special devices and tools, it is an indisputable fact: you can watch videos about a certain manipulation many times, you may perfect know the algorithm of its performance, but without ever trying to do it yourself, it is impossible to master this manipulation.&#x0D; Studying at a medical university has its own specifics, so distance learning cannot completely replace the traditional educational process and prepare future doctors for further practice.

Current Evidence and Directions for Future Research in eHealth Physical Activity Interventions for Adults Affected by Cancer: Systematic Review.

BackgroundPhysical activity (PA) interventions can increase PA and improve well-being among adults affected by cancer; however, most adults do not meet cancer-specific PA recommendations. Lack of time, facility access, and travel distances are barriers to participation in PA interventions. eHealth technologies may address some of these barriers, serving as a viable way to promote PA behavior change in this population. However, no review from July 2018 has synthesized available evidence across eHealth and cancer types or examined the use of behavioral theory and behavior change techniques (BCTs), leaving important gaps in knowledge.ObjectiveThis review aims to provide a comprehensive, updated overview of evidence on eHealth PA interventions for adults with cancer by describing the current state of the literature, exploring associations between intervention characteristics and effectiveness, and identifying future research needs.MethodsMEDLINE, Embase, CINAHL, SportDiscus, Scopus, and CENTRAL were searched for eHealth PA interventions for adults affected by cancer. Study selection and data extraction were performed in duplicate, with consultation from the senior author (NCR). BCT coding, risk of bias, and completeness of reporting were performed using standardized tools. Results were summarized via narrative synthesis and harvest plots. Weight analyses were conducted to explore the associations between intervention characteristics and effectiveness.ResultsA total of 71 articles (67 studies) involving 6655 participants (mean age 56.7 years, SD 8.2) were included. Nearly 50% (32/67) of the articles were published after July 2018. Significant postintervention PA increases were noted in 52% (35/67) of the studies, and PA maintenance was noted in 41% (5/12) of the studies that included a follow-up. Study duration, primary objectives, and eHealth modality (eg, websites, activity trackers, and SMS text messaging) varied widely. Social cognitive theory (23/67, 34%) was the most used theory. The mean number of BCTs used across the studies was 13.5 (SD 5.5), with self-monitoring, credible sources, and goal setting being used in >90% of studies. Weight analyses showed the greatest associations between increased PA levels and PA as a primary outcome (0.621), interventions using websites (0.656) or mobile apps (0.563), interventions integrating multiple behavioral theories (0.750), and interventions using BCTs of problem solving (0.657) and action planning (0.645). All studies had concerns with high risk of bias, mostly because of the risk of confounding, measurement bias, and incomplete reporting.ConclusionsA range of eHealth PA interventions may increase PA levels among adults affected by cancer, and specific components (eg, websites, use of theory, and action planning) may be linked to greater effectiveness. However, more work is needed to ascertain and optimize effectiveness, measure long-term effects, and address concerns with bias and incomplete reporting. This evidence is required to support arguments for integrating eHealth within PA promotion in oncology.

Students’ Learning Status and Expectations with Online Distance Learning

The Covid-19 pandemic in Malaysia, from the first wave in March 2020 till to-date the third wave has disrupted all formal face-to-face learning at all levels of education. A shift in the teaching mode was necessary from face-to-face to any accessible and feasible online distance learning (ODL) platform. However, due to lack of necessary technological equipment and an unsupportive environment, students are still reluctant to adopt online distance learning, particularly in rural areas. Furthermore, little was known about the readiness of engineering students at Diploma level to experience this new mode of learning. This study looked into students' ODL learning status and their expectations for ODL educational decisions. Data was collected for three weeks in a university in the southern region of Peninsular Malaysia using online Google Forms. Data was analysed descriptively and direct quotes from the open-ended section of the questionnaire were presented to support the descriptive analysis. The data highlights the need to involve many stakeholders and properly plan the ODL instructions for effective technology-based education. The outcomes of this research will help the educators, students and the government to redesign and restructure ODL post-Covid-19 for successful teaching and learning.

Photothermal-Induced Electrochemical Interfacial Region Regulation Enables Signal Amplification for Dual-Mode Detection of Ovarian Cancer Biomarkers.

Detection sensitivity of an electrochemical immunosensor mainly depends on the accessible distance toward the sensing interface; regulating the electrochemical interfacial region thereon is an effective strategy for signal amplification. Herein, a photothermal-regulated sensing interface was designed based on a near-infrared (NIR)-responsive hydrogel probe for ultrasensitive detection of human epididymis protein 4 (HE4). Silver nanoparticle-deposited graphene oxide nanosheet (AgNPs@GO) hybrids as electrochemical signal tags and a photothermal transducer, which were encapsulated in the poly(N-isopropylacrylamide) (pNIPAM) hydrogel, were used to develop the NIR-responsive GO@AgNPs-pNIPAM hydrogel probe. Under NIR light irradiation, the excellent photothermal effect of AgNPs@GO hybrids not only rapidly converted NIR light into heat for temperature readout but also triggered the shrinkage behavior of the hydrogel for electrochemical signal amplification. Compared with the conventional sandwich immunoassay, the shrinkage behavior of the hydrogel signal probe endowed itself with interface regulation capability to improve the electrochemical reaction efficiency; on the basis of ensuring the extended outer Helmholtz plane (OHP) region, the proposed photothermal-induced interface regulation also shortened the OHP, leading to higher sensitivity. Moreover, the obtained dual-mode signals provided satisfactory accuracy for the detection of tumor markers. Therefore, this detection scheme provided an opportunity for the broad applications of the photothermal effect in clinical diagnosis.

Parent-subsidiary temporal closeness and expatriate staffing: the communication synchronicity effect

This study draws insights from media synchronicity theory (MST) to understand why and how temporal closeness between multinational enterprise (MNE) parent and subsidiary locations may affect MNEs’ employment of expatriates in their foreign subsidiaries. Parent-subsidiary temporal closeness, indicated by the working time overlap between the parent and subsidiary location, determines the extent to which synchronicity can be achieved in day-to-day communication directly at a distance. Such communication synchronicity enables MNE parents to excise control and maintain effective knowledge exchange with subsidiaries without having to rely on costly expatriates. As such, we posit a negative relationship between parent-subsidiary temporal closeness and the deployment of expatriates in a subsidiary, such that the expatriate ratio decreases with an increase of overlapping working time between the parent and subsidiary location. Furthermore, we posit that the negative relationship can be further moderated by factors enabling or constraining parent-subsidiary synchronous communication such as digital accessibility and linguistic distance. Empirical analyses of a sample of 3,500 subsidiaries of 1,801 Japanese MNEs between 1990 and 2009 support our theorizing. Theoretical and practical implications for MNEs’ global operations are discussed.

Simultaneous distribution of wired and two 2 × 2 MIMO wireless OFDM signals over an integrated RoF-PON system

Abstract In this paper, the integration of the radio over fiber technology into a passive optical network (RoF-PON) is proposed to simultaneously distribute wired and two wireless standards each one transports 2 × 2 multi-input multi-output orthogonal frequency division multiplexing (MIMO-OFDM) signals. This simultaneous transmission is operated based on a single centralized optical wavelength and enabled by a polarization division multiplexing technique. The proposed RoF-PON system offers high spectral efficiency and is designed for unlicensed industrial, scientific, and medical bands at 2.4 and 5.8 GHz. The system performance is assessed by measuring the bit error rates (BERs) according to different access distances up to 30 km. After determining the optimum extinction ratio (ER) to modulate the baseband wired signal that allows jointly optical modulation of wireless signals using the same optical wavelength; all the 2 × 2 quadrature amplitude modulation (QAM) MIMO-OFDM wireless signals with a wired signal are successfully delivered without using forward error correction limit. Additionally, the system reliability has been confirmed by adopting other modulations schemes such as 8 and 16 phase-shift keying (PSK) that maintained good constellation diagrams performances. Whereas, the wired signal is analyzed according to its BER and quality Q-factor including high-quality eye diagram patterns. Also, the results revealed that the MIMO-OFDM signals mapped by 16 QAM scheme are given a better performance than PSK schemes when they are accompanied with high data rate baseband wired signal via a PON distance of 30 km.

Mobile energy hub planning for complex urban networks: A robust optimization approach

The electricity grid with a high penetration of renewable energy can enable travelers to travel free of emissions using state-of-the-art electric vehicles (EVs). Extensive electric vehicle demands at the peak-times, and an increase in electricity consumption due to population growth, have led to higher utility infrastructure investments. Mobile energy hubs i.e. clustered EVs parked in a dedicated location, can be used as an innovative demand-side management solution to reduce long-term utility infrastructure investments. They can store and release electricity to the grid based on consumer demand. However, a scientific planning approach for grid integration has been overlooked. Accordingly, this study proposes a comprehensive framework required to plan and develop mobile energy hubs based on optimization of life cycle cost, access distance and parking duration considering the temporal variation of EV recharging demands. The results of the study show that the framework developed can minimize lifecycle costs, and improve infrastructure utilization by accounting for the interests of all stakeholders. The total cost with the proposed robust optimization model under uncertainties of 50% is lesser than the robust cost calculated from a scenario-based approach. Furthermore, the developed framework is useful for recharging infrastructure planners to devise the deployment schedules and attract investors based on the economic viability of the planned strategies.