Lifetime Constraints Research Articles

Research on Multi-Core Curvature Sensing Measurement Based on PPP-BOTDA.

To address the issue of spatial resolution limitations in traditional Brillouin optical time-domain analysis systems due to phonon lifetime constraints, we employed pre-pumped pulse technology. Additionally, to mitigate the double-peak phenomenon observed in pre-pumped Brillouin optical time-domain analysis systems, we implemented a two-sided band interference method to reduce the linewidth of the double-peak fitting. We conducted bending measurements on three eccentric cores and intermediate cores spaced 120° apart. Our results demonstrate that the system described in this paper can achieve a spatial resolution of 30 cm, with bimodal linewidths of 23.1 MHz and 16.0 MHz. Using the parallel transmission frame algorithm, we determined the curvature of a seven-core fiber with a curvature diameter of approximately 10 cm to be 20.67 m-1, with an error margin of 3.2%.

First experimental results on lifetime-aware wind farm control

The study presents the methodology, implementation, and first results of the experimental test of a lifetime-aware wind farm control (WFC) approach. The novel strategy goes beyond the conventional WFC formulations and aims to maximise profit while ensuring fulfilment of a desired lifetime. Damage due to fatigue is formulated using a cost model and is also limited by a lifetime constraint. The control strategy is based on yaw-induced wake steering and utilises a tool chain of power and damage estimators. The experiment was conducted with three model turbines in a boundary layer wind tunnel, which allowed the simulation of a realistic dynamic variation of the wind direction. The novel strategy is compared to conventional greedy operation, as well as to the classical maximum power strategy. The results show that the novel control strategy can improve the economic performance of the farm.

JWST detection of extremely excited outflowing CO and H2O in VV 114 E SW: A possible rapidly accreting IMBH

Mid-infrared (mid-IR) gas-phase molecular bands are powerful diagnostics of the warm interstellar medium. We report the James Webb Space Telescope detection of the CO v = 1 − 0 (4.4 − 5.0 μm) and H2O ν2 = 1 − 0 (5.0 − 7.8 μm) ro-vibrational bands, both in absorption, toward the “s2” core in the southwest nucleus of the merging galaxy VV 114 E. All ro-vibrational CO lines up to Jlow = 33 (Elow ≈ 3000 K) are detected, as well as a forest of H2O lines up to 130, 13 (Elow ≈ 2600 K). The highest-excitation lines are blueshifted by ∼180 km s−1 relative to the extended molecular cloud, which is traced by the rotational CO (J = 3 − 2) 346 GHz line observed with the Atacama Large Millimeter/submillimeter Array. The bands also show absorption in a low-velocity component (blueshifted by ≈30 km s−1) with lower excitation. The analysis shows that the bands are observed against a continuum with an effective temperature of Tbck ∼ 550 K extinguished with τ6 μmext ∼ 2.5−3 (Ak ∼ 6.9 − 8.3 mag). The high-excitation CO and H2O lines are consistent with v = 0 thermalization with Trot ≈ 450 K and column densities of NCO ≈ (1.7 − 3.5)×1019 cm−2 and NH2O ≈ (1.5 − 3.0)×1019 cm−2. Thermalization of the v = 0 levels of H2O requires either an extreme density of nH2 ≳ 109 cm−3, or radiative excitation by the mid-IR field in a very compact (< 1 pc) optically thick source emitting ∼1010 L⊙. The latter alternative is favored, implying that the observed absorption probes the very early stages of a fully enshrouded active black hole (BH). On the basis of a simple model for BH growth and applying a lifetime constraint to the s2 core, an intermediate-mass BH (IMBH, MBH ∼ 4.5 × 104 M⊙) accreting at super-Eddington rates is suggested, where the observed feedback has not yet been able to break through the natal cocoon.

Global path planning with lifetime constraint model-based offline optimized loading strategy for vehicle fuel cell system

To promote the commercialization of fuel cell vehicles, simultaneously improving the dynamic response and durability of fuel cells under loading conditions are extremely important. Since it can seriously affect the system design and lifespan of the fuel cell system. Unfortunately, fast and reliable loading is a pair of contradictory relationships and it needs an optimal loading slope under variable loading conditions. Therefore, this paper proposes a global path planning (GPP) model by considering lifetime limitations to solve the problem. Firstly, the initial GPP model is established according to the initial power and target power, which is exploited to determine exploratory and calibration tests. Subsequently, the trade-off relationship between fast and reliable loading is addressed by the multi-objective cost function based on the dynamic weight coefficient adjustment method to construct a complete GPP model. Eventually, the optimal slopes solution is calculated by the Dijkstra algorithm. The superiority, robustness, and feasibility of the presented method are successfully verified under a 90 kW fuel cell system test bench. The verification test results show that compared with the reference solution, the utilization of optimal solution loading can significantly reduce the dynamic response time by 22.22% and improve the loading reliability by 40.93%. Moreover, the number of calibration tests determined based on the GPP model is 85.19% less than that of the traditional method. Thus, the proposed loading strategy can load quickly and reliably.

Gauged Le − Lμ − Lτ symmetry, fourth generation, neutrino mass and dark matter

We present two models where the familiar leptonic symmetry Le−Lμ−Lτ is a gauge symmetry. We show how anomaly cancellation constrains the allowed theories, with one of them requiring a fourth sequential chiral standard model fermion generation and a second one with three generations, requiring gauging of (Le−Lμ−Lτ)−(B1−B2−B3) with Ba representing the baryon number of the ath generation quarks. Unlike global Le−Lμ−Lτ models which always leads to inverted mass hierarchy for neutrinos, the gauged version can lead to normal hierarchy. We show how to construct realistic models in both the cases and discuss the dark matter candidate in both. In our model, the breaking of U(1)Le−Lμ−Lτ is responsible for neutrino mass via type-I mechanism whereas the real part of U(1)Le−Lμ−Lτ breaking scalar field (called ϕ here) plays the role of freeze-in dark matter candidate. Since ϕ is unstable, for it to qualify as dark matter, its lifetime must be larger than the age of the Universe, implying that the relic of ϕ is generated through freeze-in mechanism and its mass must be less than an MeV. We also discuss the possibility of explaining both muon and electron g−2 while being consistent with the DM relic density and lifetime constraints.

VAP-A intrinsically disordered regions enable versatile tethering at membrane contact sites.

Membrane contact sites (MCSs) are heterogeneous in shape, composition, and dynamics. Despite this diversity, VAP proteins act as receptors for multiple FFAT motif-containing proteins and drive the formation of most MCSs that involve the endoplasmic reticulum (ER). Although the VAP-FFAT interaction is well characterized, no model explains how VAP adapts to its partners in various MCSs. We report that VAP-A localization to different MCSs depends on its intrinsically disordered regions (IDRs) in human cells. VAP-A interaction with PTPIP51 and VPS13A at ER-mitochondria MCS conditions mitochondria fusion by promoting lipid transfer and cardiolipin buildup. VAP-A also enables lipid exchange at ER-Golgi MCS by interacting with oxysterol-binding protein (OSBP) and CERT. However, removing IDRs from VAP-A restricts its distribution and function to ER-mitochondria MCS. Our data suggest that IDRs do not modulate VAP-A preference toward specific partners but do adjust their geometry to MCS organization and lifetime constraints. Thus, IDR-mediated VAP-A conformational flexibility ensures membrane tethering plasticity and efficiency.

An optimized ticket manager based energy‐aware multipath routing protocol design for IoT based wireless sensor networks

SummaryRecently, wireless sensor networks (WSNs) and Internet of Things (IoTs) have emanated as an indispensable assets that play a critical role in revolutionizing the field of data communication. Owing to the evolution of communication standards, research trends in IoT based wireless sensor networks have been rapidly progressing toward achieving effective data routing with a prolonged network lifetime and minimized energy consumption. In this article, an optimized ticket manager based energy‐aware multipath routing protocol (TMERP) is proposed. The proposed protocol design comprises three important functional entities: ticket manager (TM), routing planner (RP), and backup node (BN). The TM is responsible for controlling and monitoring all the constraints related to networking. Then, the RP minimizes the overall complexity of the optimal resource allocation by avoiding an end‐to‐end delay. Finally, the BN facilitates efficient data routing through the optimal selection of routing paths using the node trust evaluation and backup process to minimize data loss. Hence, the proposed multipath routing system has a distinct advantage in enhancing the network lifetime constraint with minimal energy consumption owing to the collective performance of its functional entities. The simulation results of the experimental studies show that the proposed protocol design achieved an improved performance in terms of network energy, throughput, and network operational lifetime by 39.3%, 47.9%, and 10.5%, respectively when compared with similar existing protocols.

Mathematical programming formulations and metaheuristics for biological sample transportation problems in healthcare

In this paper, a problem arising from a real-world healthcare application is addressed, dealing with the transportation of biological samples from blood draw centers to a main laboratory. The problem can be modeled as a Vehicle Routing Problem with time-windows and samples lifetime constraints, in which transfers and multiple visits at specific nodes (i.e., the spokes) are allowed to get extra lifetimes of the samples. Mixed Integer Linear Programming formulations and Hybrid Adaptive Large Neighborhood Search (H-ALNS) algorithms have been developed for the problem. Computational experiments on different sets of instances based on real-life data provided by the Local Healthcare Authority of Bologna, Italy, show the effectiveness of the proposed algorithms. More precisely, the H-ALNS algorithms are able to find solutions in which all the samples are delivered on time, unlike the real case where lifetime requirements are usually not fully respected.

New smart home energy management systems based on inclining block-rate pricing scheme

AbstractThere are wide applications of block-rate pricing schemes in many countries. However, there are no significant studies that apply this common tariff for smart home energy management systems. In this paper, a three-time-frame energy management scheme has been proposed for photovoltaic (PV)-powered grid-connected smart homes based on the well-known mixed-integer linear programming optimization technique. This paper provides three original and novel smart home energy management algorithms that depend on the most common residential tariff specifically in developing countries. Three different management concepts have been studied for a typical Egyptian house. The concepts of shifting load, vehicle-to-home and reducing air conditioning have been tested according to a commonly applied slab tariff. The proposed scheme considers the home battery extending lifetime constraints. It also preserves comfortable lifestyle limits for home users according to Arab housing climatic conditions and culture. Moreover, the economic feasibility of integrated PV modules for the studied home has been verified according to the Egyptian tariff. The proposed energy management scheme of PV-powered home reduces the electrical power bill significantly in a wide range from 61% to only 19% of the default case bill according to the applied management technique.

LoRaWAN Communication Protocols: A Comprehensive Survey under an Energy Efficiency Perspective

Long range wide area networks (LoRaWANs) have recently received intense scientific, research, and industrial interest. LoRaWANs play a pivotal role in Internet of Things (IoT) applications due to their capability to offer large coverage without sacrificing the energy efficiency and, thus the battery life, of end-devices. Most published contributions assume that LoRaWAN gateways (GWs) are plugged into the energy grid; thus, neglecting the network lifetime constraint due to power storage limitations. However, there are several verticals, including precision agriculture, forest protection, and others, in which it is difficult or even impossible to connect the GW to the power grid or to perform battery replacement at the end-devices. Consequently, maximizing the networks’ energy efficiency is expected to have a crucial impact on maximizing the network lifetime. Motivated by this, as well as the observation that the overall LoRaWAN network energy efficiency is significantly affected by the selected communication protocol, in this paper, we identify and discuss critical aspects and research challenges involved in the design of a LoRaWAN communication protocol, under an energy efficiency perspective. Building upon our findings, research directions towards a novel GreenLoRaWAN communication protocol are given, focusing on achieving energy efficiency, robustness, and scalability.

An Efficient Swift Routing Model with Node Trust Identity Factor (SRM-NTIF) to Perform Secure Data Transmission Among IoT Gadgets

According to a United Nations survey, the number of users using the internet has increased to 3 billion in recent years. The Auto-ID Center is a research organisation that coined the word "Internet of Things" (IoT) a decade ago, describing how it utilises wired or wireless networking technologies to create a channel of communication among technologies and networks available over the Internet. Despite the fact that a swing of routing protocols has been proposed in the literature, safe and energy-efficient routing protocol is still a work in progress. Many routing protocols expressly designed for resource limited wireless devices take the same approach and have nearly achieved their full improvements. The Internet of Things (IoT) has recently gained prominence as a result of the increasing number of connected devices being used in everyday human life with network lifetime constraints. Routing expertise is essential for establishing communication between nodes. A node should be capable of self-learning, self-configuring, and self-managing by gathering local knowledge and sharing it with its neighbours. The degree of trust determines the degree of cooperation between scattered mobile nodes. The term "trust" refers to a level of assurance based on node behavior. To ensure secure and proper data transmission in IoT network, the trust level of the nodes is calculated based on node behaviour. Because of the unexpected changes in the network structure, the complex existence of IoT network, and the underived prior trust relationship between the nodes, trust computation in IoT network is a difficult task. All IoT nodes willing to engage in data transmission are given a Digital Unique Identifier (DUI), and the proposed model must define their trust identity factors. Using the DUI, the proposed Swift Routing Model with Node Trust Identity Factor (SRM-NTIF) model, node authentication is performed to verify natural and malicious nodes in the network. The proposed model is compared with the traditional methods and the results show that the proposed model performance is better in security and trust levels.

Run-Time Thermal Management for Lifetime Optimization in Low-Power Designs

In this paper, the magnitude of the temperature and stress variability of dynamic voltage and frequency scaling (DVFS) designs is analyzed, and their impact on the bias temperature instability (BTI) degradation and lifetime of DVFS designs is assessed. For this purpose, a design-time evaluation framework for BTI degradation was developed, which considered the statistical workload and die temperature profiles of DVFS operating modes. The performed analysis showed that, together with high stress variability, DVFS designs exhibited even higher temperature variability, depending on the workload and utilized operating modes, and the impact of temperature variability on lifetime could be up to 2× higher than that due to stress. In order to account for temperature variability on aging detrimental effects, a thermal management run-time system is proposed that honors the desired lifetime constraints by properly selecting temperature constraints that govern the utilized operating modes. The proposed run-time system was applied on the largest benchmark circuit from the IWLS 2005 suite, Ethernet circuit, synthesized with the 32 nm CMOS technology. The proposed system was verified to obtain lifetime and performance estimation and the trade-off with up to 35.8% and 26.3% higher accuracy, respectively, when compared to a system that ignores temperature variability and accounts for average temperature only. The proposed framework can be suitably utilized for tuning run-time throttling policies of low-power designs, thus allowing designers to optimize lifetime–performance trade-offs, depending on the requirements mandated by specific applications and operating environments.

Multi-messenger lifetime constraints on heavy decaying dark matter

Ultra-high-energy (UHE) neutrino and gamma-ray measurements will help on the dark matter (DM) quest via indirect detection. In this work we used UHE measurements of the astrophysical gamma-ray flux and we forecasted the performance of the future radio neutrino telescopes in order to see the potential limits that they could place on the lifetime of DM particles. We focused in the range of DM masses m DM = [107 — 1015] GeV. We provide the current gamma-ray limits placed by the different experimental collaborations CASA-MIA, KASCADE KASCADE-Grande, Pierre Auger Observatory, Telescope Array and EAS-MSU. We also compare this limits with the projected UHE neutrino ones from future radio neutrino telescopes in order to see the complementarity between both messengers. For a more detailed description of the analysis we refer the reader to [1, 2, 3].

Efficient Node Deployment of Large-Scale Heterogeneous Wireless Sensor Networks

Wireless Sensor Networks (WSNs) became essential in developing many applications, including smart cities and Internet of Things (IoT) applications. WSN has been used in many critical applications such as healthcare, military, and transportation. Such applications depend mainly on the performance of the deployed sensor nodes. Therefore, the deployment process has to be perfectly arranged. However, the deployment process for a WSN is challenging due to many of the constraints to be taken into consideration. For instance, mobile nodes are already utilized in many applications, and their localization needs to be considered during the deployment process. Besides, heterogeneous nodes are employed in many recent applications due to their efficiency and cost-effectiveness. Moreover, the development areas might have different properties due to their importance. Those parameters increase the deployment complexity and make it hard to reach the best deployment scheme. This work, therefore, seeks to discover the best deployment plan for a WSN, considering these limitations throughout the deployment process. First, the deployment problem is defined as an optimization problem and mathematically formulated using Integer Linear Programming (ILP) to understand the problem better. The main objective function is to maximize the coverage of a given field with a network lifetime constraint. Nodes’ mobility and heterogeneity are added to the deployment constraints. The importance of the monitored field subareas is also introduced in this paper, where some subareas could have more importance than others. The paper utilizes Swarm Intelligence as a heuristic algorithm for the large-scale deployment problem. Simulation experiments show that the proposed algorithm produces efficient deployment schemes with a high coverage rate and minimum energy consumption compared to some recent algorithms. The proposed algorithm shows more than a 30% improvement in coverage and network lifetime.

Low-Power Status Updates via Sleep-Wake Scheduling

We consider the problem of optimizing the freshness of status updates that are sent from a large number of low-power sources to a common access point. The source nodes utilize carrier sensing to reduce collisions and adopt an asynchronized sleep-wake scheduling strategy to achieve a target network lifetime (e.g., 10 years). We use <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">age of information</i> (AoI) to measure the freshness of status updates, and design sleep-wake parameters for minimizing the weighted-sum peak AoI of the sources, subject to per-source battery lifetime constraints. When the sensing time (i.e., the time duration of carrier sensing) is zero, this sleep-wake design problem can be solved by resorting to a two-layer nested convex optimization procedure; however, for positive sensing times, the problem is non-convex. We devise a low-complexity solution to solve this problem and prove that, for practical sensing times that are short, the solution is within a small gap from the optimum AoI performance. When the mean transmission time of status-update packets is unknown, we devise a reinforcement learning algorithm that adaptively performs the following two tasks in an “efficient way”: a) it learns the unknown parameter, b) it also generates efficient controls that make channel access decisions. We analyze its performance by quantifying its “regret”, i.e., the sub-optimality gap between its average performance and the average performance of a controller that knows the mean transmission time. Our numerical and NS-3 simulation results show that our solution can indeed elongate the batteries lifetime of information sources, while providing a competitive AoI performance.

Gamma ray signals from cosmic ray scattering on axionlike particles

Dark Matter (DM) may be comprised of axion-like particles (ALPs) with couplings to photons and the standard model fermions. In this paper we study photon signals arising from cosmic ray (CR) electron scattering on background ALPs. For a range of masses we find that these bounds can place competitive new constraints on the ALP-electron coupling, although in many models lifetime constraints may supersede these bounds. In addition to current Fermi constraints, we also consider future e-Astrogram bounds which will have greater sensitivity to ALP-CR induced gamma-rays.

Evaluation of external tubular configurations for a high-temperature chloride molten salt solar receiver operating above 700 °C

Next-generation concentrating solar power (CSP) tower technologies target operating temperatures exceeding 700 °C to increase the thermal-to-electric conversion efficiency. Molten chloride salts are one possible alternative to current commercial molten nitrate salts to enable the higher operating temperature. This paper analyzes the predicted optical, thermal-fluids, and structural performance of traditional external tubular solar receiver configurations applied with a chloride salt heat transfer fluid (HTF) and inlet/outlet temperatures of 500 °C/735 °C, and considers sensitivity analysis and optimization relative to receiver sizing, tube sizing, number of panels, flow circuit configurations, and solar flux concentration under constraints on internal velocity, pressure drop, wall thickness, and required creep-fatigue lifetime. The high temperature conditions increase the significance of inelastic deformation mechanisms such as creep relative to that expected in commercial 565 °C nitrate salt designs. High-temperature creep and creep-fatigue damage in the metal alloy tubes are the key factors that limit allowable solar flux concentration and achievable receiver thermal efficiency at the near-800 °C wall temperature conditions. For a traditional external cylindrical receiver configuration, the design parameters and conditions capable of satisfying all constraints produced, at best, a design point receiver efficiency of 78.2%, or 80.5% when excluding receiver intercept efficiency. Variation in the optimal receiver performance relative to uncertainty in the binding maximum velocity, minimum wall thickness, and minimum lifetime constraints is presented.

Independent Luminescent Lifetime and Intensity Tuning of Upconversion Nanoparticles by Gradient Doping for Multiplexed Encoding.

Luminescent materials with engineered optical properties have been developed for multiplexed labeling detection, where encoding capacity plays a pivotal role in the efficiency. However, multi-dimensional optical identities are usually not independent which essentially hinder the practical encoding numbers to access theoretical capacity. In this work, we carefully studied the sensitizer gradient doping structure in near-infrared (NIR) excitable upconversion nanoparticles (UCNPs) and managed to achieve independent emission intensity and lifetime tuning. With the orthogonally tunability, it breaks the constraint of intensity (k) and lifetime (n) correlation and expands the practical encoding number to theoretical value as (k+1)n -1 in binary encoding. This method can also be combined with previous lifetime engineering as well to realize high level multiplexing.

Independent Luminescent Lifetime and Intensity Tuning of Upconversion Nanoparticles by Gradient Doping for Multiplexed Encoding

AbstractLuminescent materials with engineered optical properties have been developed for multiplexed labeling detection, where encoding capacity plays a pivotal role in the efficiency. However, multi‐dimensional optical identities are usually not independent which essentially hinder the practical encoding numbers to access theoretical capacity. In this work, we carefully studied the sensitizer gradient doping structure in near‐infrared (NIR) excitable upconversion nanoparticles (UCNPs) and managed to achieve independent emission intensity and lifetime tuning. With the orthogonally tunability, it breaks the constraint of intensity (k) and lifetime (n) correlation and expands the practical encoding number to theoretical value as (k+1)n−1 in binary encoding. This method can also be combined with previous lifetime engineering as well to realize high level multiplexing.

Late Acceptance Hill-Climbing Matheuristic for the General Lot Sizing and Scheduling Problem with Rich Constraints

This paper considers the general lot sizing and scheduling problem with rich constraints exemplified by means of rework and lifetime constraints for defective items (GLSP-RP), which finds numerous applications in industrial settings, for example, the food processing industry and the pharmaceutical industry. To address this problem, we propose the Late Acceptance Hill-climbing Matheuristic (LAHCM) as a novel solution framework that exploits and integrates the late acceptance hill climbing algorithm and exact approaches for speeding up the solution process in comparison to solving the problem by means of a general solver. The computational results show the benefits of incorporating exact approaches within the LAHCM template leading to high-quality solutions within short computational times.