Main Configurations Research Articles

Radiation Environment in the LHC Arc Sections During Run 2 and Future HL-LHC Operations

The Large Hadron Collider (LHC) at the European Organization for Nuclear Research (CERN) is the largest accelerator in the world, spanning a circumference of 26.7 km. During its operation, small fractions of the beams are being continuously lost. This leads to mixed-field radiation that might affect electronic equipment through both cumulative and single-event effects. This article considers the radiation environment during Run 2 (years 2015-2018) in the LHC arc sectors that constitute approximately 70% of the accelerator, housing a huge amount of electronics. There, the main magnets' configuration is periodic, and the main contributor to losses is the interaction of the beams with residual gas molecules, resulting in relatively low-radiation levels, as opposed to different parts of the LHC. However, as presented, there are locations where losses are no longer dominated by residual gas. In these locations, radiation levels are higher by up to more than two orders of magnitude and could, therefore, be problematic in terms of cumulative radiation effects on electronics. In this article, the dose measurements from beam loss monitors have been combined with the FLUKA simulation for the arc sectors in order to indirectly retrieve the residual gas densities and radiation profile under the magnet cryostats, at the equipment level, for the losses caused by residual gas. Estimations for the radiation levels in the arc sectors during the high-luminosity LHC era and potential implications for the electronics are discussed as well.

New design chart for CFRP strengthened RC walls with opening in one-way action

Reinforced Concrete (RC) walls have been widely used in the construction of medium/high-rise buildings due to their substantial advantages, including fast construction and cost-effectiveness. Nowadays, custom architectural designs have given rise to openings in RC walls for various purposes including doors, windows and vents. Creating such openings within the existing walls alters the ultimate strength of the wall and introduces changes to the intended load path through the element. The situation will become more complex when considering the various support conditions and possible opening configurations. In this research, a comprehensive numerical investigation is completed on Carbon Fibre Reinforced Polymer (CFRP) strengthened RC walls. For the first time, a design chart is proposed for the axial load design of CFRP strengthened RC walls considering two main factors, opening configurations and CFRP layouts. The proposed charts have been verified and validated against existing experimental data and available axial load design formulae. It was found that the proposed design chart can reasonably predict the axial ultimate load capacity of CFRP strengthened RC walls. Step by step instructions are presented to employ these charts and case studies are also provided for clarification and illustration.

Ionization of adenine in the presence of Na+ in the gas phase and water

In this work, the photoelectron spectrum of adenine (AD) interacting with one and two bare and microhydrated Na+ (AD-Na+, Na+-AD-Na+, AD-[Na(H2O)n]+ and [Na(H2O)n]+-AD-[Na(H2O)n]+) have been calculated in two environments including the gas phase and water, separately. The symmetry adapted/cluster configuration interaction (SAC-CI) methodology was employed to calculate the first to fifth ionization energies (IEs) of AD. The photoelectron spectra of AD-Na+ structures showed a shift to higher binding energy, depending on the interaction site of Na+, compared to the spectrum of bare AD in gas phase while a slight shift to lower binding energy was observed for the spectrum of the most stable structure of AD-Na+ in water compared to bare AD in the same condition. In the presence of second Na+, the gas phase photoelectron spectrum of Na+-AD-Na+ shifted to higher binding energy compared to the spectrum of AD-Na+. This energy shift was nearly independent of the interaction site of second Na+ and decreased, considerably in the water environment. The microhydration of Na+ in the AD-Na+ and Na+-AD-Na+ structures in the gas phase, shifted their photoelectron spectra to lower binding energies compared to the spectra of corresponding unhydrated structures depending on the number of water molecules. A similar trend was also observed in water. The hydration of Na+ could decrease the ionization energy of AD-Na+ and Na+-AD-Na+ structures in water even lower than the ionization energies of bare AD in the same conditions. The main electronic configurations of the ionization bands of each structure were determined and their changing with the Na+ interaction site, number of Na+ and hydration of Na+ were explained. The kind and contribution of Lewis orbitals in the canonical molecular orbitals participating in ionization were determined for each structure.

Flexible riser-bend stiffener top connection analytical model with I-tube

The flexible riser top connection to the floating unit is a critical region considering extreme loading and fatigue lifetime assessment and is generally protected by a bend stiffener to limit the curvature in this region. The top connection usually interface the floating unit with two main configurations: i) end-fitting and bend stiffener directly connected to a riser balcony or ii) riser connected to the floating unit in the end of an I-tube, which reduces the end-fitting bending loading, and bend stiffener assembled to a bellmouth with a given inclination in relation to the I-tube longitudinal axis. The traditional modeling approach considers the riser/bend stiffener system attached to the floating unit, representative of the first configuration. A more realistic modeling approach, capturing the complex interactions of flexible riser/bend stiffener with I-tube interface can be employed for preliminary assessment with less conservatism. In this work, a large deflection analytical beam model is developed for the riser top connection with I-tube considering the bellmouth transition region with a straight rigid surface followed by a curved section. The riser follows a nonlinear bending behavior described by a bilinear moment vs curvature function and the bend stiffener polyurethane material exhibits nonlinear elastic symmetric response represented by a power law function. It is assumed that there is no gap between the riser and the bend stiffener and the riser is fixed in the end-fitting position. The mathematical formulation of the statically indeterminate system results in three systems of coupled differential equations combined with the corresponding multipoint boundary conditions to be numerically solved by an iterative procedure. A case study is carried out with a 7” flexible riser protected by a bend stiffener connected to an inclined I-tube bellmouth. The system is subjected to extreme loading conditions and the influence of the sleeve shape and I-tube length on the riser curvature distribution, including the end-fitting position, and contact forces between the riser/sleeve and riser/bend stiffener sections are assessed.

Microbial fuel cell system: a promising technology for pollutant removal and environmental remediation.

The microbial fuel cell (MFC) system is a promising environmental remediation technology due to its simple compact design, low cost, and renewable energy producing. MFCs can convert chemical energy from waste matters to electrical energy, which provides a sustainable and environmentally friendly solution for pollutant degradations. In this review, we attempt to gather research progress of MFC technology in pollutant removal and environmental remediation. The main configurations and pollutant removal mechanism by MFCs are introduced. The research progress of MFC systems in pollutant removal and environmental remediation, including wastewater treatment, soil remediation, natural water and groundwater remediation, sludge and solid waste treatment, and greenhouse gas emission control, as well as the application of MFCs in environmental monitoring have been reviewed. Subsequently, the application of MFCs in environmental monitoring and the combination of MFCs with other technologies are described. Finally, the current limitations and potential future research has been demonstrated in this review.

Fabrication of Polymeric Microparticles by Electrospray: The Impact of Experimental Parameters.

Microparticles (MPs) with controlled morphologies and sizes have been investigated by several researchers due to their importance in pharmaceutical, ceramic, cosmetic, and food industries to just name a few. In particular, the electrospray (ES) technique has been shown to be a viable alternative for the development of single particles with different dimensions, multiple layers, and varied morphologies. In order to adjust these properties, it is necessary to optimize different experimental parameters, such as polymer solvent, voltage, flow rate (FR), type of collectors, and distance between the collector and needle tip, which will all be highlighted in this review. Moreover, the influence and contributions of each of these parameters on the design and fabrication of polymeric MPs are described. In addition, the most common configurations of ES systems for this purpose are discussed, for instance, the main configuration of an ES system with monoaxial, coaxial, triaxial, and multi-capillary delivery. Finally, the main types of collectors employed, types of synthesized MPs and their applications specifically in the pharmaceutical and biomedical fields will be emphasized. To date, ES is a promising and versatile technology with numerous excellent applications in the pharmaceutical and biomaterials field and such MPs generated should be employed for the improved treatment of cancer, healing of bone, and other persistent medical problems.

Raman spectroscopy analysis of molecular configuration forms of the macular xanthophylls

AbstractMacula lutea, the yellow spot of the retina of the human eye, comprises three xanthophyll pigments: lutein, zeaxanthin, and meso‐zeaxanthin, playing numerous important biological functions. Macular xanthophylls are exposed to relatively strong illumination in the eye, owing to the fact that the yellow spot is localized on the optical axis, in the frontal layer with respect to photoreceptors. In the present work, we address the problem of photostability and possible photoisomerization of macular xanthophylls with the application of resonance Raman spectroscopy. The results show photostability of the two major isomers of the macular xanthophylls, all‐trans and 9‐cis, and efficient photoconversion of the 13‐cis isomer to the 9‐cis and mostly to the all‐trans form. We report the Raman spectra of the main molecular configuration forms of the macular xanthophylls, opening an avenue for the examination of their possible presence and photoconversion in natural systems.

Machine learning strategies applied to the control of a fluidic pinball

The wake stabilization of a triangular cluster of three rotating cylinders is investigated. Experiments are performed at Reynolds number Re ∼ 2200. Flow control is realized using rotating cylinders spanning the wind-tunnel height. The cylinders are individually connected to identical brushless DC motors. Two-component planar particle image velocimetry measurements and constant temperature hot-wire anemometry were used to characterize the flow without and with actuation. Main open-loop configurations are studied and different controlled flow topologies are identified. Machine learning control is then implemented for the optimization of the flow control performance. Linear genetic algorithms are used here as the optimization technique for the open-loop constant speed-actuators. Two different cost functions J are considered targeting either drag reduction or wake symmetrization. The functions are estimated based on the velocity from three hot-wire sensors in the wake. It is shown that the machine learning approach is an effective strategy for controlling the wake characteristics. More significantly, the results show that machine learning strategies can reveal unanticipated solutions or parameter relations, in addition to being a tool for optimizing searches in large parameter spaces.

Sub-Frame Layer Rate Distortion Optimization for High Efficiency Video Coding

This paper proposes a sub-frame layer RDO algorithm to further improve coding performance of low-delay hierarchical prediction structure in High Efficiency Video Coding. In the proposed algorithm, each frame is segmented into two sub-frames according to motion intensity, and a sub-frame layer is taken as a basic optimizing unit. An inter-frame dependency model is proposed to quantify inter-frame dependency of a frame or a sub-frame. The proposed inter-frame dependency model is composed of two parts, Laplace distribution based direct inter-frame dependency model and distortion propagation chain. The direct inter-frame dependency model is used to evaluate dependency caused by direct reference, and the distortion propagation chain shows the relationship between direct reference and indirect reference. With quantified inter-frame dependency, Lagrange optimization is then used to solve the optimal $\lambda $ -QP pair for each sub-frame layer in frame layer 1 (L1) to frame layer 4 (L4). For frame layer 0 (L0), additional L0 frames are adaptively inserted according to inter-frame dependency of the previous L0 frame, and the optimal $\lambda $ -QP pair for each sub-frame in L0 is solved using Lagrange optimization. When peak signal to noise ratio is used as quality criterion, the proposed algorithm achieves 7.0% and 7.0% bit-rate reduction with lowdelay_P_main (LDP) and lowdelay_main (LDB) configurations respectively; when structural similarity is used as quality criterion, the proposed algorithm achieves 13.3% and 13.1% bit-rate reduction with LDP and LDB configurations respectively.

Optimised annual performance of hybrid solar energy MED-TVC desalination plants with and without preheating

In the current study, energy, exergy, economic and environmental (4E) analysis for a multi-effect desalination plant with and without feed brine preheater integrated with a steam boiler and solar hybrid system for three coastal cities of southern Iran during a year is investigated. Four main configurations of hybrid/MED-TVC, hybrid/MED-TVC.FH, boiler/MED-TVC and boiler/MED-TVC.FH are considered. By using artificial bee colony algorithm, systems were optimised. The results show that: using feed brine preheater, the unit cost reduced by 6.5% for the system with a boiler and 3.8% for the hybrid system.

Optimised annual performance of hybrid solar energy MED-TVC desalination plants with and without preheating

In the current study, energy, exergy, economic and environmental (4E) analysis for a multi-effect desalination plant with and without feed brine preheater integrated with a steam boiler and solar hybrid system for three coastal cities of southern Iran during a year is investigated. Four main configurations of hybrid/MED-TVC, hybrid/MED-TVC.FH, boiler/MED-TVC and boiler/MED-TVC.FH are considered. By using artificial bee colony algorithm, systems were optimised. The results show that: using feed brine preheater, the unit cost reduced by 6.5% for the system with a boiler and 3.8% for the hybrid system.

Analytical methods for the assessment of hanger forces of a suspension bridge based on measured main cable configuration

The accurate measurement of the hanger tensile forces of suspension bridges is crucial for construction control and bridge maintenance. However, the commonly used vibration frequency method is not applicable to the short-hanger force assessment. The configuration of the main cable of a suspension bridge is closely related to hanger forces so that the main cable configuration can reflect the hanger forces. Based on the multi-segment catenary theory, this study proposed an analytical algorithm for the reverse assessment of hanger forces based on the measured configuration data of the main cable. First, the relationship between the hanger force and two critical parameters, that is, the horizontal force of the main cable and the catenary parameter, is established, in which the influence of the saddle arc on the main cable configuration is considered. Then, the horizontal force of the main cable is used as the breakthrough point, and a geometric condition (measuring the coordinates of a non-hanging point on the main cable) or a mechanical condition (measuring the tension of a long hanger by the vibration frequency method) is added. Using the nonlinear generalized reduced gradient method, the nonlinear equations are solved, and all hanger forces are identified. The proposed method feasibility and effectiveness are proved using a suspension bridge with a main span of 730 m as an example. The results show that the algorithm of adding a mechanical condition is lower in sensitivity, less affected by the accuracy of the additional condition, higher in precision, and easier to control, comparing to that of adding a geometric condition. Meanwhile, the horizontal force of the main cable and each hanger force exhibit a nearly perfect linear correlation.

Optimal Main Heat Transport system configuration for a nuclear power plant

Selection of an optimal Main Heat Transport (MHT) system configuration for a nuclear power plant (NPP) is an activity of high significance, as it influences the safety and operational aspects. This paper brings out the methodology for selection of optimal MHT configuration of NPPs which provides enhanced safety along with ease of operation. The criterion for selection of NPP-MHT configuration have been developed for enhancing safety and ease of operation. As a case study, an innovative MHT configuration has been arrived for a channel type Boiling Water Reactor (BWR) which further improves safety. Some of the multiple failure Design Extension Conditions (DEC) scenarios without SCRAM which lead to severe core damage, for commonly deployed MHT configurations, do not encounter any core heat up with this optimal MHT configuration, for a prolonged duration with Emergency Core Cooling System (ECCS). To demonstrate the effect of MHT system configuration on safety, the Natural Circulation Advanced Boiling Water Reactor (NCABWR) has been considered in this study. Though NCABWR is considered for demonstration purpose, similar methodology can be used for devising or conceptualizing an optimal MHT system configuration for any other NPP. The NCABWR is a four inter-connected loop channel type BWR with natural circulation based passive MHT cooling at all power levels. Following the recent DEC events, more emphasis is laid on very low or no radiological impact in the public domain and no requirement of evacuation in the spirit of “more good than harm”. New NPPs like NCABWR come closer to these requirements. With the mostly passive safety systems, NCABWR can avoid and mitigate DEC. The MHT system configuration for such NPPs need to be selected optimally based on the safety enhancement. In this study, optimal NCABWR MHT configuration has been further evolved based on all the Postulated Initiating Events (PIEs) including multiple failures, such as Anticipated Transients without Scram (ATWS), 200% inlet header break Loss of Coolant Accident (LOCA) without reactor trip etc. Several MHT configurations were conceptualized based on comprehensive overall design, layout requirements and reactor specific PIEs like a LOCA with a postulated break in the four partitioned ECCS header compartment. LOCA in one of the four ECCS header compartment required a mandatory interconnection among all the four MHT loops through the Common Reactor Inlet Header (CRIH) without any partition. This analysis and related issues signaled towards requirement of development of an optimal MHT configuration. The objective of the present study is to configure the MHT components and the ECCS in such an optimal formation so as to provide an enhanced performance in terms of heat removal during adverse conditions. This paper brings out clearly the important aspects needed to be considered while selecting the MHT configuration for the NPPs with enhanced safety even for ATWS-DEC scenarios, without compromising the ease of operation. The development of advanced accident tolerant fuels with improved performance, an improved/optimal MHT NPP configuration is inevitable to ensure safety.

Assessment of a Turbo-Electric Aircraft Configuration with Aft-Propulsion Using Boundary Layer Ingestion

In this paper, a turbo-electric propulsion system was analyzed, and its performance was assessed. The aircraft considered here was a single-aisle, medium-range configuration targeting a capacity of 150 Pax. The propulsion concept comprised two boosted geared turbofan engines mounted under-wing. Those main engines were supported by an electrically driven aft-propulsor contributing to the thrust generation and by taking advantage of ingesting the boundary layer of the fuselage for potentially higher levels of propulsive efficiency and allowing for the improved operation of the main engines. The performance assessment as carried out in the context of this paper involved different levels: Firstly, based on the reference aircraft and the detailed description of its major components, the engine performance model for both main engines, as well as for the electrically driven aft-propulsor was set up. The methodology, as introduced, has already been applied in the context of hybrid-electric propulsion and allowed for the aforementioned aircraft sizing, as well as the subsequent gas turbine multi-point synthesis (simulation). A geared turbofan architecture with 2035 technology assumptions was considered for the main engine configuration. The present trade study focused on the design and performance analysis of the aft-propulsor and how it affected the performance of the main engines, due to the electric power generation. In order to allow for a more accurate description of the performance of this particular module, the enhanced streamline curvature method with an underlying and pre-optimized profile database was used to design a propulsor tailored to meet the requirements of the aft propulsor as derived from the cycle synthesis and overall aircraft specification; existing design expertise for novel and highly integrated propulsors could be taken advantage of herein. The resulting performance characteristics from the streamline curvature method were then fed back to the engine performance model in a closely coupled approach in order to have a more accurate description of the module behavior. This direct coupling allowed for enhanced sensitivity studies, monitoring different top-level parameters, such as the thrust/power split between the main engines and the aft propulsor. As a result, different propulsor specifications and fan designs with optimal performance characteristics were achieved, which in return affected the performance of all subsystems considered.

The experience of visual art in the rhythm of global transformations. New models of artistic action

A complete analysis of Ukrainian contemporary visual art’s functioning models and their features, and international scene from the middle of 2010’s until present time. There were comprehended and shown reactions of creative intellectual activity on the cultural globalization and imposed dictate of dominant global art-structures. Outlined is the nature of changes in the main institutional configuration of today’s contemporary art, including forms, connections, means and the amplitude of interaction between the participants. There was noticed a significant shift in the Ukrainian art field, shaped approximately after the year of 2010, connected with the emergence of entirely new communicative relationships, that are developing outside of pyramidal institutional vertical, and are carried out in the network. There were identified new creations of the contemporary art in the texture of artistic life — art-things. Also, there was demonstrated the significance of the artist’s signature in the new alliances of the virtual forms of art. Formulated a new content of the creative aspect of artist’s profession, that is determined and demanded by global trends. Indicated are the main prerequisites to actualize the interest to the artistic collectivism in both local and international environment. Clarified the key points of the phenomena of an overwhelming amount of texts regarding visual arts and the dominance of press-release. Found out the future perspectives of the new formats of artistic actions and the main structural elements of the system of Ukrainian visual arts in the context of global discourse.

Climate Forcing and Trends of Organic Aerosols in the Community Earth System Model (CESM2)

AbstractThe Community Earth System Model version 2 (CESM2) includes three main atmospheric configurations: the Community Atmosphere Model version 6 (CAM6) with simplified chemistry and a simplified organic aerosol (OA) scheme, CAM6 with comprehensive tropospheric and stratospheric chemistry representation (CAM6‐chem), and the Whole Atmosphere Community Climate Model version 6 (WACCM6). Both, CAM6‐chem and WACCM6 include a more comprehensive secondary organic aerosols (SOA) approach using the Volatility Basis Set (VBS) scheme and prognostic stratospheric aerosols. This paper describes the different OA schemes available in the different atmospheric configurations of CESM2 and discusses differences in aerosol burden and resulting climate forcings. Derived OA burden and trends differ due to differences in OA formation using the different approaches. Regional differences in Aerosol Optical Depth with larger values using the comprehensive approach occur over SOA source regions. Stronger increasing SOA trends between 1960 and 2015 in WACCM6 compared to CAM6 are due to increasing biogenic emissions aligned with increasing surface temperatures. Using the comprehensive SOA approach further leads to improved comparisons to aircraft observations and SOA formation of ≈143 Tg/yr. We further use WACCM6 to identify source contributions of OA from biogenic, fossil fuel, and biomass burning emissions, to quantify SOA amounts and trends from these sources. Increasing SOA trends between 1960 and 2015 are the result of increasing biogenic emissions aligned with increasing surface temperatures. Biogenic emissions are at least two thirds of the total SOA burden. In addition, SOA source contributions from fossil fuel emissions become more important, with largest values over Southeast Asia. The estimated total anthropogenic forcing of OA in WACCM6 for 1995–2010 conditions is −0.43 W/m2, mostly from the aerosol direct effect.

Monitoring and Modelling of the LHC Emittance and Luminosity Evolution in 2018

Operating at 6.5 TeV, the LHC surpassed the expectations and delivered an average of 66 fb–1 integrated luminosity to the two high luminosity experiments ATLAS and CMS by the end of 2018. In order to provide a continuous feedback to the machine coordination for further optimizing the performance, an automated tool for monitoring the main beam parameters and machine configurations, has been devised and extensively used. New features like the coupling between the two planes and effects of noise, were added to the numerical model used since 2016 to calculate the machine luminosity. Estimates, based both on simulations and on observed beam parameters, were reported fill-by-fill as well as in overall trends during the year. Highlights of the observations including the observed additional emittance blow up (on top of IBS, SR and elastic scattering) as well as additional losses (on top of the expected proton burn off) are presented for the 2018 data. Finally, cumulated integrated luminosity projections from the model for the entire 2018 data based on different degradation mechanisms are compared also with respect to the achieved luminosity.

Handling Differential Mode Conducted EMC in Modular Converters

This article presents the analysis and management of differential mode conducted EMI in modular converters made from associations of standard conversion cells. Two main configurations, inputs in series—outputs in parallel and inputs in parallel—outputs in series are studied with the objective to define a generic EMI management technique, independent from the number of conversion standard cells implemented. First, analysis is carried out from a theoretical point of view based on simplified models. Second, filtering solutions are introduced and compared. Especially, centralized versus distributed filtering techniques are compared with the objective to find generic solutions. The results are compared and validated with practical characterizations.

Francisco Suárez and the Complexities of Modernity

I present here a key to reading the work of Jesuit thinker Francisco Suárez in the context of the plurality and complexity of modernity. I show the main configuration that defines modernity in its hegemonic version, as well as its limitations. From there, I propose how Suárez’s work can be understood from the perspective of its own Ignatian and Jesuit spiritual framework and in relation to the development of modernity. Although a dominant version of modernity has historically prevailed, modernity cannot be understood as a uniform process but one that has been articulated and expressed in different civilizing missions since the Renaissance. One modern way of responding to the socio-cultural challenges of the Renaissance was articulated by the Society of Jesus. I believe that in light of what I term an “Ignatian modernity,” we can better understand Suárez’s intellectual mission, its historical virtuality, and the possibilities marginalized by hegemonic modernity.

Achilles tendon rupture repair: Biomechanical comparison of the locking block modified Krackow technique and the Giftbox technique

BackgroundOpen Giftbox repair of the Achilles tendon has good biomechanical advantages, but it is not minimally invasive. We designed a peritendon fixation technique, the “Locking Block Modified Krackow” (LBMK) technique, to meet minimally invasive needs. This study used a simulated protocol of early rehabilitation to compare the biomechanics of LBMK with those of the Giftbox technique. MethodsTwenty fresh bovine Achilles tendon specimens were randomly assigned to either the LBMK group or the Giftbox group. The LBMK technique and the Giftbox technique were used as the main suture configurations, and transverse sutures were used as secondary suture configurations in both groups. Each repaired specimen was subjected to two cyclic loading protocols (20–100 N, 20–190 N). The gapping between the tendon ends was measured after each stage of loading. Finally, all specimens underwent a load-to-failure test at a stretching rate of 25 mm/s. ResultsAfter the first loading stage, the mean tendon gapping was 0.76±0.44 mm in the LBMK group and 0.86 ± 0.47 mm in the Giftbox group (p = 0.620). After the second loading test, the average gapping measures of the LBMK and Giftbox groups were 3.8 ± 1.9 mm and 4.2 ± 2.2 mm, respectively (p = 0.466). Finally, the catastrophic load to failure was 732.8 ± 138 N in the LBMK group and 645.5 ± 121 N in the Giftbox group. The difference was statistically significant (p = 0.023). ConclusionBoth the LBMK and Giftbox techniques meet the requirements of early rehabilitation, but the suture strength in the LBMK group was significantly higher than that in the Giftbox group.