In this work, new summation-integral approximation operators based on a versatile generalization of the classic Szász-Mirakjan type operators, and incorporating the Boas-Buck polynomials are ...considered. We show how the proposed operators can get reduced to a multitude of operators involving classic approximation operators studied over past many decades. Wex nomenclate the individual cases hybrid generalizations of Bernstein, Baskakov, Lupaş and Szász-Mirakjan operators, each incorporating the Boas-Buck, Brenke, Sheffer and Appell polynomials. Indispensable properties of the proposed operators based on first and second order modulus of continuity are derived. Approximation on weighted space is also considered. In addition, quantitative Voronovskaja-type theorems have very recently been acknowledged as valuable properties for approximating functions. These form a noteworthy part of the present work.
The significant offshore wind energy potential of Oregon faces several challenges, including a power grid which was not developed for the purpose of transmitting energy from the ocean. The grid ...impacts of the energy resource are considered through the lenses of (i) resource complementarity with Variable Renewable Energy resources; (ii) correlations with load profiles from the four balancing authorities with territory in Oregon; and (iii) spatial value to regional and coastal grids as represented through a production cost model of the Western Interconnection. The capacity implications of the interactions between offshore wind and the historical east-to-west power flows of the region are discussed. The existing system is shown to accommodate more than two gigawatts of offshore wind interconnections with minimal curtailment. Through three gigawatts of interconnection, transmission flows indicate a reduction of coastal and statewide energy imports as well as minimal statewide energy exports.
•Temporal characterization of marine energy resources, at varying time scales.•Characterized wave, tidal, and ocean currents, and compared to wind and solar.•Data based exposition of grid benefits ...for wave power at high renewable scenarios.•Data based exposition of higher capacity adequacy and stability for wave power.•Detailed discussion on market implications of grid integration of marine energy.
In this paper, the applicability of marine renewable energy (MRE) for potential grid applications is presented. We show that many of the unique value streams from marine-based electricity generation resources stem from their inherent temporal characteristics, especially when compared to wind and solar. Specifically, in this work, we evaluate the timing value for three types of MRE resources: (a) tidal, (b) wave, and (c) ocean currents. First, through a suite of novel metrics, such as resource availability, persistence, and versatility, we evaluate the temporal value characteristics of these resources. Second, through a more grid-oriented numerical study, we comment on the potential ramifications of those temporal characteristics in context of energy balancing and effective load carrying capability for one marine-based resource i.e., wave. Finally, we further our understanding of the relative advantages that may be leveraged by operating wave-based generation in tandem with more established renewable resources, such as wind and solar. Our results indicate that compared to wind and solar, MRE resources are consistently more available and persistent on an hourly level throughout an entire year of operation. In addition, wave resources are also seen to reduce the balancing requirements within the power system. Our work focuses on sites specific to the United States (US) and a parallel study for a location in Great Britain (GB). Results are found to be consistent for sites in both the US and GB, implying that the grid benefits discussed in this work could apply to a number of locations globally.
•Biomedical implants demand has increased recently due to poor lifestyles.•Titanium and its alloys have shown promising results for biomedical implants.•HAp based coating has proven better due its ...similar composition as human bone.•The surface modification technique improves the bioactivity of the bio-implants.•The review discusses various recent implant developments with critics the recent developments.
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The need for advancement in biomaterials that stimulate the repair, replacement, or recovery of gentle body tissues and bones keeps growing as the population ages. Although substantial research has been carried out over the last decade to develop medical implants for bone regeneration and healing body tissues, implants still fail due to infection, fracture, corrosion, and extreme load. Depending upon the permanent or temporary implant requirement, various materials such as metals, ceramics, and polymers are used as implantable materials. The article discusses various metals, alloys and polymeric materials and their application as medical implants. Titanium implants have shown promising application as a bone replacement, and their alloys play a critical role in orthopaedic and dental procedures. However, they show various drawbacks such as Ti-6Al-4V alloy shows toxicity, Ti-Zr alloy exhibits lack of mechanical stability and complexity in processing and Ti-Ni alloy show toxicity and low thermal conductivity. Surface modification technique such as PIII&D, CVD, etc., contribute to attaining robust biocompatibility and improving their mechanical properties. Titanium alloys, their properties, and future scope as implantable material have been extensively discussed. Given that biocompatibility and bone response are important determinants of implants’ clinical performance, published studies of in-vitro and in-vivo research have been critically discussed in the article. Bioactivity is an essential characteristic required to stimulate biological response with host tissue and bond with the surrounding tissue. A critical discussion on bioactive materials and enhancement of bioactivity has been included in the article. The paper also examines and discusses several physical and chemical surface modification techniques and their utilization in the development of medical implants. This study discusses biomaterials’ overall performance and applications in biological systems, vital for enhancing medical implants and tissue engineering. This review contains critics for young researchers planning to embark on the development of implants for biomedical applications.
Marine energy resources could promote clean energy and resilience of coastal and island microgrids, and thus, these applications are a key future market for marine energy development. To demonstrate ...these benefits, this paper illustrates how inclusion of wave resources into energy resilience solutions can improve overall grid efficiency and sustainability, as well as maintain electricity supply during grid outages. The paper describes a case study evaluation of the potential to add wave energy to the Moloka'i grid as Hawaii strives to meet a 100% clean energy target. The Microgrid Component Optimization for Resilience tool is used to simulate operation in off-grid conditions and size different combinations of wave, solar photovoltaic (PV), wind, storage, and fuel resources required to meet resilience objectives. This research investigates how including wave resources in a microgrid contributes to reducing or eliminating biofuel generation, producing a zero-greenhouse gas emission profile in the latter case, and avoiding the over-sizing of PV and battery systems to accommodate periods of unavailability or high demand. Insight from this paper supports the value proposition of wave resources for future markets and informs the relationship between marine generators and microgrids or isolated grids.
Purpose
The Lumi-Solve photo-angioplasty drug eluting balloon catheter (DEBc) may afford safety advantages over current DEBc. Lumi-Solve utilises the guidewire (GW) port and lumen to deliver ...fibre-optic UV365nm light to the angioplasty balloon which may be problematic. We explore and evaluate alternative Lumi-Solve design options to circumvent fibre-optic use of the GW port and lumen which may enhance efficacy and clinical utility.
Methods
Effects of guidewire shadowing (GWS) on visible and UV365nm light transmission were evaluated and modelled in-silico. To evaluate the effect of a dedicated intra-balloon fibre-optic port, modified angioplasty balloons and sections of translucent polyethylene terephthalate (PET) GW port tubing were utilised. Investigation of the effect of GWS on chemical and biological photo-activation of balloon surface drug was performed utilising LCMS analysis and inhibition of histone deacetylase activity (HDACi) was measured in human umbilical vein endothelial cells (HUVEC).
Results
Parallel fibre-optic and GW port configurations generated a GWS of approximately 18.0% of the evaluable balloon surface area and attenuated both visible and UV light intensity by 20.0–25.0% and reduced chemical photo-activation of balloon surface drug and HDACi by at least 40–45%. Alternative fibre-optic port configurations including a spiral design significantly mitigated GWS effects on UV light transmission.
Conclusions
To avoid use of the GW port and its associated complications a dedicated third port and lumen for the Lumi-Solve fibre-optic may be required. To maximize balloon surface chemical and biological photo-activation, non-parallel, intra-balloon, fibre-optic lumen trajectories, including a spiral design may be useful.
Defining long duration energy storage Twitchell, Jeremy; DeSomber, Kyle; Bhatnagar, Dhruv
Journal of energy storage,
April 2023, 2023-04-00, 2023-04-01, Letnik:
60, Številka:
C
Journal Article
Recenzirano
Odprti dostop
Accelerating the deployment of variable renewable energy is changing the operational characteristics of the electric grid and creating an emerging need for storage technologies with extended ...energy-duration capabilities to maintain grid reliability. Extended or “long-duration” energy storage scales for supporting future grids are not well defined but can be anticipated to grow by estimating gaps in renewable performance of a decarbonized grid. Variable generation resources create a mismatch between electricity generation and use; as the amount of variable generation on the grid grows, so too do mismatches. This study reviews current uses of energy storage and how those uses are changing in response to emerging grid needs, then assesses how the power generation industry and academia are defining long-duration storage and organizing research efforts to develop commercial technologies. Using an illustrative example of a decarbonized grid, the study identifies the depth and breadth of future energy mismatches and concludes that two classes of long-duration energy storage will be needed in a decarbonized grid; one class lasting up to 20 h to manage daily cycles and one lasting for weeks or months to manage seasonal cycles. This study elucidates the necessity of long-duration energy storage in a decarbonized grid and may inform long-term planning processes. Grid planners can play an important role in the development of long-duration energy storage technologies through granular identification of storage needs that creates a market signal for investment in and development of the necessary technologies to provide a reliable and resilient grid for the future.
•Long duration energy storage is loosely defined, yet will be essential to the reliability of our future grid.•This study examines current definitions, services provided, and forecasts a future scenario involving a decarbonized grid.•Two classes of long duration energy storage emerge, first is a daily ten to twenty hour variety, while the second is a weekly to monthly duration.
Highly nanocrystalline carbonated hydroxyapatite (CHAp) is synthesized by hydrothermal technique with four different stoichiometric compositions for microstructural and mechanical analysis. HAp is ...one of the most biocompatible material and addition of carbonate ions lead to increase in fracture toughness highly required in biomedical applications. The structural properties and its purity as single phase is confirmed by X-ray diffraction. Lattice imperfections and structural defects is investigated using XRD pattern model simulation, i.e. Rietveld's analysis. The substitution of CO32− in HAp structure leads to a decrease in crystallinity which ultimately lessens crystallite size of sample as verified by XRD analysis. FE-SEM micrographs confirms the formation of nanorods with cuboidal morphology and porous structure of HAp and CHAp samples. The particle size distribution histogram validates the constant decrease in size due to carbonate addition. The mechanical testing of prepared samples revealed the increase in mechanical strength from 6.12 MPa to 11.52 MPa due to the addition of carbonate content, which leads to a rise in fracture toughness, a significant property of an implant material from 2.93 kN to 4.22 kN. The cumulative effect of CO32− substitution on HAp structure and mechanical properties has been generalized for the application as biomedical implant material or biomedical smart materials.
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•Investigated the structural properties of Carbonated-Hydroxyapatite using Rietveld Analysis.•Microstructural characterization and particle size distribution are discussed through FESEM images.•Carbonate substitution in HAp matrix enhanced mechanical strength and fracture toughness.•Outlined the scope of Carbonated-Hydroxyapatite biomaterial for biomedical implant application.
Due to natural variability and uncertainty, the ever-increasing penetration of solar generation in Hawaii presents challenges to power grid operators to maintain reliable system operation. Demand ...response (DR) has the potential to be a cost-effective tool for Hawaii to reach its aggressive renewable energy goals while maintaining the reliability of power grids. The Hawaii Public Utilities Commission has approved the Hawaiian Electric Company’s revised portfolio of DR programs. The companies have released a grid services purchase agreement and subscribed an initial tranche of load into their DR programs. This paper presents innovative analytical methods and comprehensive economic assessment for distributed photovoltaics (PV) paired with battery energy storage systems (BESSs) for two new DR programs, including fast frequency response and capacity grid service. Optimal dispatch and sizing methods are proposed for the paired system considering different tariff schedules and PV compensation programs across five islands. It was found that while the best resource configuration and potential economic benefits vary with tariff structure, a BESS paired with PV can be optimally dispatched to generate multiple value streams simultaneously. Compensation from DR programs is an important value stream to help increase the cost-effectiveness of the integrated system.
•Innovative methods are proposed for evaluating photovoltaics paired with batteries.•Key techno-economic characteristics of photovoltaics and batteries are captured.•Photovoltaics compensation and demand response are considered simultaneously.•Techniques are proposed to linearize the optimal dispatch and sizing problems.•Comprehensive assessment is performed by customer type across the Hawaiian Islands.
Coastal communities face unique socio-ecological risks and vulnerabilities due to their geography and related resource dependencies. The resilience of such communities and their capacity to adapt to ...social, economic, and environmental change is consequently shaped by the diverse characteristics and values that guide their development. Marine renewable energy (MRE) is one promising solution for augmenting coastal resilience and environmental sustainability while increasing energy security, energy affordability, and socioeconomic benefits. The socio-technical nature of energy transitions more broadly necessitates place-based and multidisciplinary analyses to gain a full picture of the needs of communities. This article uses potential MRE development (specifically tidal energy) in two coastal communities as a lens to explore how social perceptions and MRE's technical potential might be integrated to improve alignment between community values and energy development. We draw on semi-structured interviews with community representatives from Sitka, Alaska and the San Juan Islands in Washington State and present findings on how energy development objectives are shaped by community values, resource relations, and institutional relations. Through modeling exercises, we also show the grid benefits of MRE deployment in the San Juan Islands, highlighting MRE's role in deferring costly electric infrastructure upgrades and reducing fuel imports when paired with solar photovoltaic (PV) or battery storage. These findings offer viable pathways for future MRE research, commercial validation, and deployment that directly respond to the place-based opportunities and challenges of coastal communities.
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