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Numerical investigation on slip-flow and heat transfer characteristics in the entrance region of elliptical microchannels
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Data will be made available on request.This paper concentrates on the numerical investigation of slip-flow and heat transfer characteristics in the entry region of elliptical microchannels under isothermal or isoflux boundary conditions. Slip boundaries caused by rarefaction effect are implemented using user-defined functions. The impacts of Reynolds number (25≤ Re ≤ 1000), Knudsen number (0.01≤ Kn ≤ 0.1), Peclet number (17.5 ≤ Pe ≤ 700) and aspect ratio (0.2≤ ε ≤ 1) on the apparent friction factor Reynolds number product fappRe and local Nusselt number Nu(x) are discussed in detail. The results demonstrate that at the entrance region, fappRe decreases with increasing Re, especially for ε = 0.33, Kn = 0.01 and Re < 500. However, it is independent of Re at fully developed region. At ε = 0.75 and x∗ = 0.0001, when Pe ranges from 17.5 to 350, Nu(x) is decreases by 87 % at the T boundary. The value of Nu(x) for Kn = 0.04 is reduces by 333 when compared with no-slip case at Pe is 17.5. These indicate that heat transfer near the inlet can be effectively enhanced by axial heat conduction. While rarefaction reduces friction losses and weakens the effect of axial heat conduction. Generalized correlations are proposed for fully developed Nu.This work was financially supported by Chunhui Plan Collaborative Research Project of Ministry of Education (No. HZKY20220343), the Opening Foundation of Hubei Key Laboratory of Hydroelectric Machinery Design & Maintenance (No. 2023KJX05), and International Science and Technology Cooperation Project of Hubei Province (No. 2023EHA016). The authors acknowledge support from the Brunel University London BRIEF award and the Royal Society Research Grant (RGS\R2\222256)
The economics of concentrating solar power (CSP): Assessing cost competitiveness and deployment potential
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No data was used for the research described in the article.A global transition to sustainable energy systems is underway, evident in the increasing proportion of renewables like solar and wind, which accounted for 12 % of global power generation in 2022. The shift to a low-carbon economy will likely require a substantial increase in energy storage in the near future. In this context, concentrating solar power (CSP) is viewed as a promising renewable energy source in the coming decades. However, high generation costs compared to other renewable technologies remain a key barrier inhibiting wider deployment of CSP. Compared to solar PV and onshore wind alternatives, CSP cannot currently compete on the levelized cost of electricity (LCoE). This review provides a comprehensive overview of the vital economic factors and considerations for large-scale CSP expansion. The current state of the market reveals about 8 GW of installed global CSP capacity in 2023, with rapid growth occurring in China, Chile, South Africa and the Middle East. Key economic parameters discussed in this study include capital costs, capacity factors, operating expenses and LCoE. Installation costs for CSP declined by 50 % over the past decade, falling to the current range of 20–60 per kW is now considered economical. Capacity factors increased from 30 % to more than 50 % (depending on location) through larger storage capacities and higher operating temperatures. Operations and maintenance costs now range from 0.31 per kWh in 2010 to $0.10 per kWh in 2022. Ongoing innovations in materials, components integrated systems and optimization can further reduce capital expenditures, enhance performance and decrease LCoE. However, appropriate incentives and financing mechanisms remain vital to support continued CSP technology maturation and cost reductions. With its inherent dispatchability and storage capabilities, CSP can become a cost-competitive renewable energy source, but design optimizations and accurate economic appraisals are imperative for CSP to achieve its vast sustainability potential
Influence of Safety Culture on Safety Outcomes of a Hydrogen–CCS Plant
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All data have been included in the paper, including equations for the Vensim model that is given in Appendix A.This article investigates how safety culture impacts the safety performance of blue hydrogen projects. Blue hydrogen refers to decarbonized hydrogen, produced through natural gas reforming with carbon capture and storage (CCS) technology. It is crucial to decide on a suitable safety policy to avoid potential injuries, financial losses, and loss of public goodwill. The system dynamics approach is a suitable tool for studying the impact of factors controlling safety culture. This study examines the interactions between influencing factors and implications of various strategies using what-if analyses. The conventional risk and safety assessments fail to consider the interconnectedness between the technical system and its social envelope. After identifying the key factors influencing safety culture, a system dynamics model will be developed to evaluate the impact of those factors on the safety performance of the facility. The emphasis on safety culture is directed by the necessity to prevent major disasters that could threaten a company’s survival, as well as to prevent minor yet disruptive incidents that may occur during day-to-day operations. Enhanced focus on safety culture is essential for maintaining an organization’s long-term viability. H2-CCS is a complex socio-technical system comprising interconnected subsystems and sub-subsystems. This study focuses on the safety culture sub-subsystem, illustrating how human factors within the system contribute to the occurrence of incidents. The findings from this research study can assist in creating effective strategies to improve the sustainability of the operation. By doing so, strategies can be formulated that not only enhance the integrity and reliability of an installation, as well as its availability within the energy networks, but also contribute to earning a good reputation in the community that it serves.This research received no external funding
The ePIC Experiment Physics Program Overview
Get PDFPresented at the 30th Cracow Epiphany Conference on Precision Physics at High Energy Colliders, Cracow, Poland, 8–12 January, 2024.The electron–Proton/Ion Collider Experiment (ePIC) Collaboration was formed to design, build, and operate the Electron–Ion Collider (EIC) project detector. Measurements to be performed with ePIC aim to address some of the most profound questions in Quantum Chromodynamics (QCD) related to the emergence of nuclear properties by precisely imaging gluons and quarks inside protons and nuclei. This paper presents an overview of the current configuration of the ePIC detector and its physics program
Investigation of Pressure Drop and Heat Transfer Characteristics in a Microchannel with Pin-Fins
Get PDFPin-fin heat sinks are now considered one of the possible solutions for the thermal management of small-scale devices requiring high heat dissipation rates. Pin-fins with fixed diameters, different heights and spacing were numerically investigated in the current study for a range of Re=200-1000. The micro-channel cross-section with pins at the bottom surface measures 55 mm in length and has a cross-sectional area of 1 mm x 1 mm. The fin height ranges from 0.2 to 0.8 mm and the distance between pin-fins ranges from 3-6 mm. The Box-Behknen method was used to determine the number of numerical runs based on the parametric range of pin height and spacing and the Re number. Input data and corresponding outputs were presented using the Genetic Aggregation Response Surface Methodology. An optimum pin height and spacing in terms of heat transfer rates was obtained. It has been observed that at the optimum desing considering the highest Performance Evlauation Criteria(PEC) value the microchannel with pin-fins can provide an enhancement of 364% in heat transfer rates compared to the microchannel without pins, while the corresponding increase in pressure drop reaches up to 162%.Engineering & Physical Sciences Research Council project ref. EP/T03338X/1 (BOiliNg flows in SmAll and microchannels (BONSAI)); Alişan Gönül acknowledges support through the TÜBİTAK BİDEB (2219 Programme) for this one-year fellowship for postdoctoral studies at Brunel University London
Investigation of electrostatic properties of pharmaceutical propellants
Get PDFThis thesis was submitted for the award of Doctor of Philosophy and was awarded by Brunel University LondonThis study addresses the intricate field of measuring electrical volume resistivity in hydrofluorocarbons, specifically focusing on the measurement and application of resistivity in pharmaceutical propellants. Presented research introduces a novel method to measure resistivity in propellants used in metered-dose inhalers (MDIs) for respiratory diseases. It also scrutinizes the influence on the generated current in hydrofluorocarbon liquids produced by different valve stem materials and flow rates.
The initial part of this dissertation provides an in-depth review of the resistivity cell designs, developed over the past three decades, emphasizing the practical aspects of cell design and highlighting the development of cells for testing the resistivity of refrigerants in liquid phase under high pressures. This review succinctly addresses contemporary standards, limitations, and constructional details of both academic and commercial cells and intends to serve as an instrumental guide for future researchers aiming to develop custom resistivity cells for dielectric liquids. It also looks into fundamentals of electrostatic charge and charge transfer as well as into previous research about electrostatic charge influence arising from the interaction with inhaler materials, inhaler designs and drug formulation. It explores measurement methods of abovementioned charge in previous studies.
Further, this thesis examines the practical application of measuring the DC volume resistivity of pharmaceutical propellants like R134a, R152a, and R227ea, which are significant in treating respiratory diseases like asthma via metered-dose inhalers. The study elucidates the relationship between the electrical charging of aerosols, valve stem materials and the delivery efficiency of medicaments to the lungs, emphasizing the role of resistivity in this mechanism.
Overall, this thesis integrates theoretical foundations with practical developments to advance the field of electrical volume resistivity measurement in liquid hydrofluorocarbons as well as their interactions with various polymer surfaces, offering significant contributions to the understanding of resistivity in refrigerants and pharmaceutical propellants and proposing innovative solutions to overcome the limitations of existing technologies
Search for <i>CP</i> violation in D° → K<sub>0</sub><sup>S</sup>K<sub>0</sub><sup>S</sup> decays in proton–proton collisions at √ = 13 TeV
No full textA version of the article is available at arXiv:2405.11606v2 [hep-ex] (https://arxiv.org/abs/2405.11606). Comments: Replaced with the published version. Added the journal reference and the DOI. All the figures and tables can be found at https://cms-results.web.cern.ch/cms-results/public-results/publications/BPH-23-005 (CMS Public Pages). Report number: CMS-BPH-23-005, CERN-EP-2024-120. Journal reference: Eur. Phys. J. C 84 (2024) 1264. Submission history: From: The CMS Collaboration: [v1] Sun, 19 May 2024 16:23:57 UTC (722 KB); [v2] Mon, 9 Dec 2024 21:50:13 UTC (722 KB).Data Availability Statement: This manuscript has no associated data. [Authors’ comment: Release and preservation of data used by the CMS Collaboration as the basis for publications is guided by the CMS data preservation, re-use, and open access policy (https://cms-docdb.cern.ch/cgi-bin/PublicDocDB/RetrieveFile?docid=6032&filename=CMSDataPolicyV1.2.pdf&version=2).]Code Availability Statement: The CMS core software is publicly available on GitHub (https://github.com/cms-sw/cmssw).A search is reported for charge-parity CP>/i> violation in D° → KSKS decays, using data collected in proton–proton collisions at √ = 13 TeV recorded by the CMS experiment in 2018. The analysis uses a dedicated data set that corresponds to an integrated luminosity of 41.6 fb⁻¹, which consists of about 10 billion events containing a pair of b hadrons, nearly all of which decay to charm hadrons. The flavor of the neutral D meson is determined by the pion charge in the reconstructed decays D*⁺ → D°π⁺ and D*⁻ → D̅⁰π⁻. The CP>/i> asymmetry in D° → KSKS is measured to be ACP>/i>(KSKS) ═ (6.2 ± 3.0 ± 0.2 ± 0.8)%, where the three uncertainties represent the statistical uncertainty, the systematic uncertainty, and the uncertainty in the measurement of the CP>/i> asymmetry in the D° → KSπ⁺π⁻ decay. This is the first CP>/i> asymmetry measurement by CMS in the charm sector as well as the first to utilize a fully hadronic final state.SCOAP³
Timing resolution of a LAPPD prototype measured with CERN PS test beams
Get PDFThe Electron-Ion Collider (EIC) facility is envisaged for the ultimate exploration of the nucleons, the nuclear matter and the strong force, thanks to its wide range of centre-of-mass energy, its large luminosity, and the polarization of its beams. The ePIC detector, designed to cope with the EIC physics potential, involves several Cherenkov radiation-based sub-systems for Particle Identification. They need reliable and effective Single Photo-Electron (SPE) sensors. We report about the timing performance of a LAPPD prototype tested with Cherenkov light produced in a quartz radiator at a CERN PS hadron test beam. Results show a SPE time resolution of 87 ps rms.SCOAP³
Measurement of inclusive and differential cross sections of single top quark production in association with a W boson in proton-proton collisions at √ = 13.6 TeV
Get PDFA version of the article is available at arXiv:2409.06444v2 [hep-ex] (https://arxiv.org/abs/2409.06444). Comments: Replaced with the published version. Added the journal reference and the DOI. All the figures and tables can be found at https://cms-results.web.cern.ch/cms-results/public-results/publications/TOP-23-008 (CMS Public Pages). Report number: CMS-TOP-23-008, CERN-EP-2024-184. Journal reference: JHEP 01 (2025) 107. Submission history: From: The CMS Collaboration: [v1] Tue, 10 Sep 2024 11:53:30 UTC (672 KB); [v2] Mon, 3 Feb 2025 16:19:11 UTC (856 KB).Data Availability Statement: This article has associated data in a data repository. Release and preservation of data used by the CMS Collaboration as the basis for publications is guided by the CMS data preservation, re-use, and open access policy (https://cms-docdb.cern.ch/cgi-bin/PublicDocDB/RetrieveFile?docid=6032&filename=CMSDataPolicyV1.2.pdf&version=2).Code Availability Statement. This article has associated code in a code repository. The CMS core software is publicly available on GitHub (https://github.com/cms-sw/cmssw).The first measurement of the inclusive and normalised differential cross sections of single top quark production in association with a W boson in proton-proton collisions at a centre-of-mass energy of 13.6 TeV is presented. The data were recorded with the CMS detector at the LHC in 2022, and correspond to an integrated luminosity of 34.7 fb⁻¹. The analysed events contain one muon and one electron in the final state. For the inclusive measurement, multivariate discriminants exploiting the kinematic properties of the events are used to separate the signal from the dominant top quark-antiquark production background. A cross section of 82.3 ± 2.1 (stat)−9.7+9.9 (syst) ± 3.3 lumi pb is obtained, consistent with the predictions of the standard model. A fiducial region is defined according to the detector acceptance to perform the differential measurements. The resulting differential distributions are unfolded to particle level and show good agreement with the predictions at next-to-leading order in perturbative quantum chromodynamics.SCOAP³
Optimised protocols to generate high titre lentiviral vectors using a novel transfection agent enabling extended HEK293T culture following transient transfection and suspension culture
Get PDFData availability statement: The data presented in this paper is available from the corresponding author upon reasonable request.Authors contributed equally to this work.Copyright © 2024 The Author(s). HIV-1 based lentiviral viruses are considered powerful and versatile gene therapy vectors to deliver therapeutic genes to patients with hereditary or acquired diseases. These vectors can efficiently transduce a variety of cell types when dividing or non-dividing to provide permanent delivery and long-term gene expression. Demand for scalable manufacturing protocols able to generate enough high titre vector for widespread use of this technology is increasing and considerable efforts to improve vector production cost-effectively, is ongoing. Current methods for LV production mainly use transient transfection of producer cell lines. Cells can be grown at scale, either in 2D relying on culturing producer cells in multi-tray flask cell culture factories or in roller bottles or can be adapted to grow in 3D suspensions in large batch fermenters. This suits rapid production and testing of new vector constructs pre-clinically for their efficacy, particle titre and safety. In this study, we sought to improve lentiviral titre over time by testing two alternative commercially available transfection reagents Fugene® 6 and Genejuice® with the commonly used polycation, polyethyleneimine. Our aim was to identify less cytotoxic transfection reagents that could be used to generate LV particles at high titre past the often used 72 h period when vector is usually collected before producer cell death is caused due to post transfection cytotoxicity. We show that LV could be produced in extended culture using Genejuice® and even by transfected cells in glass flasks in suspension. Because this delivery agent is less toxic to 293 T producer cells, following optimisation of transfection we found that LV can be harvested for more than 10 days at high titre. Using our protocol, titres of 109 TU/ml and 108 TU/ml were routinely reached via traditional monolayer conditions or suspension cultures, respectively. We propose, this simple change in vector production enables large volumes of high titre vector to be produced, cost effectively for non-clinical in vivo and in vitro applications or for more stringent downstream clinical grade vector purification
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