arXiv subjects

Roberto Rojas-Cessa

Publications and source records attributed to Roberto Rojas-Cessa.

12 recordsLinked to original sources

arXiv2025

EcoFlight: Finding Low-Energy Paths Through Obstacles for Autonomous Sensing Drones

Obstacle avoidance path planning for uncrewed aerial vehicles (UAVs), or drones, is rarely addressed in most flight path planning schemes, despite obstacles being a realistic condition. Obstacle avoidance can also be energy-intensive, making it a critical factor in efficient point-to-point drone flights. To address these gaps, we propose EcoFlight, an energy-efficient pathfinding algorithm that determines the lowest-energy route in 3D space with obstacles. The algorithm models energy consumption based on the drone propulsion system and flight dynamics. We conduct extensive evaluations, comparing EcoFlight with direct-flight and shortest-distance schemes. The simulation results across various obstacle densities show that EcoFlight consistently finds paths with lower energy consumption than comparable algorithms, particularly in high-density environments. We also demonstrate that a suitable flying speed can further enhance energy savings.

cs.RO↗

arXiv2024

Blockchain in Environmental Sustainability Measures: a Survey

Real and effective regulation of contributions to greenhouse gas emissions and pollutants requires unbiased and truthful monitoring. Blockchain has emerged not only as an approach that provides verifiable economical interactions but also as a mechanism to keep the measurement, monitoring, incentivation of environmental conservationist practices and enforcement of policy. Here, we present a survey of areas in what blockchain has been considered as a response to concerns on keeping an accurate recording of environmental practices to monitor levels of pollution and management of environmental practices. We classify the applications of blockchain into different segments of concerns, such as greenhouse gas emissions, solid waste, water, plastics, food waste, and circular economy, and show the objectives for the addressed concerns. We also classify the different blockchains and the explored and designed properties as identified for the proposed solutions. At the end, we provide a discussion about the niches and challenges that remain for future research.

cs.CR↗

arXiv2024

BalanceDN: Load-Balancing Allocation of Interest for Fast Discovery in Content Centric Networks

In Named Data Networking (NDN), data is identified by unique names instead of IP addresses, and routers use the names of the content to forward Interest packets towards the producers of the requested content. However, the current content search mechanism in NDN is complex and slow. This mechanism not only creates congestion but also hinders practical deployment due to its slowness and cumbersome nature. To address this issue, we propose a methodology, called BalanceDN, that distributes content through the network such that sought content can be found quickly. BalanceDN uses a distributed allocation of resolvers as those used by the domain name system but differs in how content is distributed. Our approach avoids flooding the network with pending interest requests and also eliminates the need for blind search when the location of content is unknown. We tested our approach on ndnSIM; a simulation platform for NDN. The results show that the proposed routing scheme utilizes far fewer network resources compared to the NDN network when retrieving content. The proposed scheme accomplishes this performance gain by leveraging a load-balanced hashing mechanism to distribute and locate the name of the content on the distributed nameserver lookup service nodes.

cs.NI↗

arXiv2023

Experiments on Computer Networks: Quickly Knowing the Protocols in the TCP/IP Suite

Manual of practical experiments on protocols used in the Internet or TCP/IP Suite. This manual is a collection of experiments that have been used in undergraduate and graduate courses taught at New Jersey Institute of Technology for a few years (ECE429 and ECE637). The manual is updated periodically to accommodate emerging needs and technologies, including virtualization of the experiments for their use during lockdowns as the one we experienced during the COVID-19 pandemic in 2020 and part of 2021. The manual may be used by all those interested in knowing and experiencing some of the basic protocols that run on the Internet. The goal is to get some understanding on protocol design and not necessarily on a particular software or operative system. Yet, the exercises will give the interested person a practical perspective. Experiments are targeted towards using Linux but most of them can also be performed on Windows operating systems.

cs.NI↗

arXiv2022

Scalability Analysis of a Global Blockchain For Immunization Records

While vaccinations continue to be rolled out to curb the ongoing COVID-19 pandemic, their verification is becoming a requirement for the re-incorporation of individuals into many social activities or travel. Blockchain technology has been widely proposed to manage vaccination records and their verification in many politically-bound regions. However, the high contagiousness of COVID-19 calls for a global vaccination campaign. Therefore, a blockchain for vaccination management must scale up to support such a campaign and be adaptable to the requirements of different countries. While there have been many proposals of blockchain frameworks that balance the access and immutability of vaccination records, their scalability, a critical feature, has not yet been addressed. In this paper, we propose a scalable and cooperative Global Immunization Information Blockchain-based System (GEOS) that leverages the global interoperability of immunization information systems. We model GEOS and describe its requirements, features, and operation. We analyze the communications and the delays incurred by the national and international consensus processes and blockchain interoperability in GEOS. Such communications are pivotal in enabling global-scale interoperability and access to electronic vaccination records for verification. We show that GEOS ably keeps up with the global vaccination rates of COVID-19 as an example of its scalability.

cs.CY↗

arXiv2022

Reducing COVID-19 Cases and Deaths by Applying Blockchain in Vaccination Rollout Management

Because a fast vaccination rollout against coronavirus disease 2019 (COVID-19) is critical to restore daily life and avoid virus mutations, it is tempting to have a relaxed vaccination-administration management system. However, a robust management system can support the enforcement of preventive measures, and in turn, reduce incidence and deaths. Here, we model a trustable and reliable management system based on blockchain for vaccine distribution by extending the Susceptible-Exposed-Infected-Recovery (SEIR) model. The model includes prevention measures such as mask-wearing, social distance, vaccination rate, and vaccination efficiency. It also considers negative social behavior, such as violations of social distance and attempts of using illegitimate vaccination proofs. By evaluating the model, we show that the proposed system can reduce up to 2.5 million cases and half a million deaths in the most demanding scenarios.

q-bio.QM↗

arXiv2020

Time Series Analysis and Correlation of Subway Turnstile Usage and COVID-19 Prevalence in New York City

In this paper, we show a strong correlation between turnstile usage data of the New York City subway provided by the Metropolitan Transport Authority of New York City and COVID-19 deaths and cases reported by the New York City Department of Health. The turnstile usage data not only indicate the usage of the city's subway but also people's activity that promoted the large prevalence of COVID-19 city dwellers experienced from March to May of 2020. While this correlation is apparent, no proof has been provided before. Here we demonstrate this correlation through the application of a long short-term memory neural network. We show that the correlation of COVID-19 prevalence and deaths considers the incubation and symptomatic phases on reported deaths. Having established this correlation, we estimate the dates when the number of COVID-19 deaths and cases would approach zero after the reported number of deaths were decreasing by using the Auto-Regressive Integrated Moving Average model. We also estimate the dates when the first cases and deaths occurred by back-tracing the data sets and compare them to the reported dates.

physics.soc-ph↗

arXiv2019

TRIDENT: A load-balancing Clos-network Packet Switch with Queues between Input and Central Stages and In-Order Forwarding

We propose a three-stage load balancing packet switch and its configuration scheme. The input- and central-stage switches are bufferless crossbars, and the output-stage switches are buffered crossbars. We call this switch ThRee-stage Clos-network swItch with queues at the middle stage and DEtermiNisTic scheduling (TRIDENT), and the switch is cell based. The proposed configuration scheme uses predetermined and periodic interconnection patterns in the input and central modules to load-balance and route traffic, therefore; it has low configuration complexity. The operation of the switch includes a mechanism applied at input and output modules to forward cells in sequence. TRIDENT achieves 100% throughput under uniform and nonuniform admissible traffic with independent and identical distributions (i.i.d.). The switch achieves this high performance using a low-complexity architecture while performing in-sequence forwarding and no central-stage expansion or memory speedup. Our discussion includes throughput analysis, where we describe the operations the configuration mechanism performs on the traffic traversing the switch, and proof of in-sequence forwarding. We present a simulation analysis as a practical demonstration of the switch performance under uniform and nonuniform i.i.d. traffic.

cs.NI↗

arXiv2019

A Split-Central-Buffered Load-Balancing Clos-Network Switch with In-Order Forwarding

We propose a configuration scheme for a load-balancing Clos-network packet switch that has split central modules and buffers in between the split modules. Our split-central-buffered Load-Balancing Clos-network (LBC) switch is cell based. The switch has four stages, namely input, central-input, central-output, and output stages. The proposed configuration scheme uses a pre-determined and periodic interconnection pattern in the input and split central modules to load-balance and route traffic. The LBC switch has low configuration complexity. The operation of the switch includes a mechanism applied at input and split-central modules to forward cells in sequence. The switch achieves 100\% throughput under uniform and nonuniform admissible traffic with independent and identical distributions (i.i.d.). These high switching performance and low complexity are achieved while performing in-sequence forwarding and without resorting to memory speedup or central-stage expansion. Our discussion includes throughput analysis, where we describe the operations that the configuration mechanism performs on the traffic traversing the switch, and proof of in-sequence forwarding. A simulation study is presented as a practical demonstration of the switch performance on uniform and nonuniform i.i.d. traffic.

cs.NI↗

arXiv2018

Beam with Adaptive Divergence Angle in Free-Space Optical Communications for High-Speed Trains

In this paper, we propose an adaptive beam that adapts its divergence angle according to the receiver aperture diameter and the communication distance to improve the received power and ease the alignment between the communicating optical transceivers in a free-space optical communications (FSOC) system for high-speed trains (HSTs). We compare the received power, signal-to-noise ratio, bit error rate, and the maximum communication distance of the proposed adaptive beam with a beam that uses a fixed divergence angle of 1 mrad. The proposed adaptive beam yields a higher received power with an increase of 33 dB in average over the fixed-divergence beam under varying visibility conditions and distance. Moreover, the proposed adaptive divergence angle extends the communication distance of a FSOC system for HSTs to about three times under different visibility conditions as compared to a fixed divergence beam. We also propose a new ground transceiver placement that places the ground transceivers of a FSOC system for HSTs on gantries placed above the train passage instead of placing them next to track. The proposed transceiver placement provides a received-power increase of 3.8 dB in average over the conventional placement of ground-station transceivers next to the track.

eess.SP↗

arXiv2018

An Energy Packet Switch for Digital Power Grids

We propose the design and electrical description of an energy packet switch for forwarding and delivery of energy in digital power grids in this paper. The proposed switch may receive energy from one or multiple power sources in the form of energy packets, store them and aggregate the contained energy, and forward the accumulated energy to requesting loads connected to one or multiple output ports of the switch. Energy packets are discrete amounts of energy that are associated in- or out-of-band with an address and other metadata. Loads receive these discrete amounts of finely-controlled energy rather than discretionary amounts after. The control and management of the proposed switch are based on a request-grant protocol. Using energy packets helps to manage the delivery of power in a reliable, robust, and function form that may enable features not yet available in the present power grid. The switch, as any element of a digital grid, uses a data network for the transmission of these requests and grants. The energy packet switch may be the centerpiece for creating infrastructure in the realization of the digital power grid. The design of the energy packet switch is based on shared supercapacitors to shape and manage discretization of energy. We introduce the design and analysis of the electrical properties of the proposed switch and describe the procedure used in the switch to determine the amount of energy transmitted to requesting loads.

eess.SP↗

arXiv2016

Power Networks: The Digital Approach

In the current analog grid, power is available at all times, to all users, indiscriminately. This makes the grid vulnerable to demand fluctuations and much effort has been invested to mitigate their effect. The Digital Power Network (DPN) is an energy-on-demand approach to power grids. In the new (digital) approach, the user initiates an energy request. This action alleviates uncertainties in energy demands. The service provider may grant the request fully or partially. Energy is then transmitted in discrete units, analogous to packets of data over a computer network. The packetized energy is routed to the user address. Because energy demands are known ahead of time, the energy provider may optimize the power distribution of the entire power network and isolate pockets of instabilities. For example, under severe energy constraints the energy provider may queue some energy requests and grant these requests later. Alternative energy resources may be seamlessly incorporated into the power network as yet another address in the system and since their energy is coded, they would be connected to specific users directly. In its simplest form, this grid can be realized by overlaying an auxiliary (communication) network on top of an energy delivery network (the current transmission lines) and coupling the two through an array of addressable digital power switches. Optimization of energy requests is the topic of this paper. We investigate the role of the network queue and provide a snapshot of its behavior in time. The DPN with a limited channel capacity and the optimal path for energy flow in a standard IEEE 39 bus are considered, as well.

cs.NI↗