Reduction In Coefficient Research Articles

Complete two-loop QCD amplitudes for tW production at hadron colliders

We have calculated the complete two-loop QCD amplitudes for hadronic tW production by combining analytical and numerical techniques. The amplitudes have been first reduced to master integrals of eight planar and seven non-planar families, which can contain at most four massive propagators. Then a rational transformation of the master integrals is found to obtain a good basis so that the dimensional parameter decouples from the kinematic variables in the denominators of reduction coefficients. The master integrals are computed by solving their differential equations numerically. We find that the finite part of the two-loop squared amplitude is stable in the bulk of the phase space. After phase space integration and convolution with the parton distributions, it increases the LO cross section at the 13 TeV LHC by about 3%.

Mathematical Models of the Phase Voltages of High-, Medium- and Low-Voltage Busbars in a Substation during a Phase-to-Ground Fault on High-Voltage Busbars

The electrical energy supply of industrial equipment is provided by electrical power stations with high- (HT), medium- (MV) and low-voltage (LV) busbars. Consumers are connected to either MV or LV busbars. In this paper, a real power station was considered, through which the gasoline extraction from the well gas installation is powered. Electric consumers (electric motors) supplied by a MV busbar have active power of 13.54 MW, and those fed by a LV busbar have active power of 6.4 MW. Since electrical consumers operate in explosive environments, the design and operating conditions are more severe than in the case of electrical installations operating in non-explosive environments. The case of a single phase-to-ground fault occurring on the HV transmission lines feeding the power station has been analysed. First, the mathematical models for the calculation of the phase voltages, the dissymmetry and asymmetry coefficients, the reduction coefficient of the plus sequence component, and the effective values of the phase voltages were established. The influence of the source impedance (the equivalent impedance of the HV transmission lines) and of the neutral point configuration of the HV/MV medium-voltage transformer on the calculated quantities was analysed. Then, the results obtained using the established mathematical models were compared with those obtained experimentally by provoking a single-phase-to-ground fault near the HV busbars of the real power station. This study has shown that the de-symmetrisation of the phase voltages of the MV and LV busbars is lower when using the Y/Δ connection for the HV/MV transformer. As a result, it is recommended the Y/Δ connection be used for this transformer, instead of the Y0/Δ connection.

Eccentric compressive behavior of square concrete-filled stainless steel tube (CFSST) stub columns

To study the eccentric compressive behavior and mechanism of square concrete-filled stainless steel tube (CFSST) stub columns, a total of 12 specimens with different steel ratio and load eccentricity under eccentric load was investigated. The results demonstrated that the failure modes of all square CFSST stub columns were the outward local buckling of the stainless steel tube at the compression side and two adjacent sides. The load-longitudinal deformation curve of specimens exhibited three stages, including elastic stage, elastic-plastic stage, and descending stage. The longitudinal strain distribution in the cross section at the mid-height of the specimens generally satisfied the plane-section assumption during the loading process. Increasing the steel ratio of specimens significantly improved the ultimate bearing capacity. Meanwhile, the ultimate bearing capacity of the specimens decreased with the load eccentricity, and the second-order effect became more pronounced with the increase in eccentricity. Finally, based on the existing specification, this study proposed a prediction formula for the eccentric bearing capacity of square CFSST stub columns by modifying the eccentric reduction coefficient accompanied by adopting the method of equivalent cross section. The formula was verified using an established database of eccentric compression CFST stub columns in the existing literatures.

Study on the intrinsic mechanisms underlying enhanced geothermal system (EGS) heat transfer performance differences in multi-wells

The effectiveness of the multi-well arrangement mode in enhanced geothermal systems in large-scale fields has been well established. However, the mechanisms that lead to variations in heat transfer performance between different numbers of well arrangements have remained unclear. In this study, the multi-well pattern was segmented into several double-well units and a mathematical model was constructed to investigate seepage heat transfer in enhanced geothermal systems using numerical simulation techniques. The lifespan and heat transfer characteristics of both multi-well and corresponding double-well units were examined, with supplementary experimental validation. Additionally, a flow reduction coefficient for multi-well systems was proposed to explain the differences in heat transfer performance caused by the pressure superposition of multiple-well seepage fields. It was found that heat extraction from a multi-well enhanced geothermal system is equivalent to the linear superposition of corresponding double-well units. Furthermore, the lifespan of multi-well systems is significantly longer than that of corresponding double-well systems due to the influence of the multi-well flow reduction coefficient. In fact, this difference can exceed threefold in nine-well arrangements, resulting in reduced efficiency of multi-well heat exchange. This work provides a novel perspective on exploring the intrinsic mechanisms that underlie differences in heat transfer performance in enhanced geothermal systems from a flow field perspective. It contributes to a better understanding of optimal well arrangement modes for enhanced geothermal systems and supports the development of large-scale geothermal fields.

Mycelium Composite with Hierarchical Porous Structure for Thermal Management.

High-performance porous materials with a low carbon footprint provide sustainable alternatives to petroleum-based lightweight foams and can help meet carbon neutrality goals. However, these materials generally face a trade-off between thermal management capabilities and structural strength. Here, a mycelium composite with a hierarchical porous structure, including both macro- and microscale pores, produced from multiple and advanced mycelial networks (elastic modulus of 1.2GPa) binding loosely distributed sawdust is demonstrated. The morphological, biological, and physicochemical properties of the filamentous mycelium and composites are discussed in terms of how they are influenced by the mycelial system of the fungi and the way they interact with the substrate. The composite shows a porosity of 0.94, a noise reduction coefficient of 0.55 at a frequency range of 250-3000Hz (for a 15mm thick sample), a thermal conductivity of 0.042Wm-1 K-1 , and an energy absorption of 18kJm-3 at 50% strain. It is also hydrophobic, repairable, and recyclable. It is expected that the hierarchical porous structural composite with excellent thermal and mechanical properties can make a significant impact on the future development of highly sustainable alternatives to lightweight plastic foams.

The value of blockchain technology in supply chains with capital constraints: from the perspective of demand volatility

AbstractBlockchain technology (BCT) has the potential to revolutionize the supply chain financing (SCF) system and mitigate the detrimental effects of demand volatility on SCF. As one of the first to examine the effects of BCT implementation in SCF from the perspective of demand volatility, we focus on the impacts of BCT on equilibrium and whether the retailer has the incentive to adopt BCT. We perform a comparative analysis of the Stackelberg game involving three parties under scenarios with and without BCT adoption. We find that when the demand volatility reduction coefficient is sufficiently large, BCT can facilitate a reduction of the ordering quantity while still sustaining the same service level, thus avoiding excessive inventory, and reducing the associated risk of bankruptcy. Additionally, the decreased bankruptcy risk enabled the bank to reduce interest rates. The adoption of BCT can improve the profit of the retailer when the adoption cost of BCT is sufficiently low. Our findings provide management insights into when the small and medium‐sized enterprises should adopt BCT and the interactive decision‐making of all parties in the SCF business after BCT adoption.

The machining parameter optimisation during the machining of the Cr-Mn austenitic stainless steel by the topsis method

The Cr-Mn stainless steel (austenitic) was dry turned in a lathe. A carbide tool (Indoloy) was used for the machining. The speed (v), feed (f), and depth of cut (DOC, d) were the input parameters. The experimental work was done following the Taguchi L 27 design plan. The chip reduction coefficients (CRC) and the von Mises stresses (VMS) were determined for all the experimental conditions. The TOPSIS (Technique for Order of Preference by Similarity to the Ideal Solution) method was used to optimise the process parameters. The optimal conditions were attainable at high speed (v = 100 m/min.), moderate feed (f = 0.1 mm/rev.), and moderate DOC (d = 1 mm). At optimized machining conditions, the VMS was 3429.5 MPa and the CRC was 1.6. The VMS was higher for the lower speed, and the VMS was lower for the higher speed. The higher VMS was attributed to the formation of strain-induced martensite (SIM). The lower VMS was due to the dynamic recrystallization (DRX) at the higher temperature for the higher speed. For the higher speed, the DRX and the dynamic precipitation (DP) occurred at the chip surface (under).

Exploring the effect of building openings and orientation on induced loads due to extreme flood events

Understanding the impact of building features on flood-induced loads remains a major challenge. This study experimentally investigated the effect of building openings and orientation on horizontal forces and overturning moments by unsteady extreme floods. The physical model experiments for flood impacts were conducted concerning three intensity flood events (Hi), four porosities (P) resulting by opening, and seven orientations (γ) by building rotation. Measurement of impact forces and moments on the building model was carried out to explore the flood impacts on structures under unsteady flow conditions. By introducing a reduction coefficient of maximum horizontal force ηF, the influence of the porosity and orientation on flood loads was discussed. Results showed that either the building openings or the orientation exhibit a reduction effect on the resulting force and moment, and the magnitude of the reduction is negatively related to the flood intensity. For the permeable building with oriented exposures, the reduction coefficient ηF showed a W-shaped variation trend concerning γ at certain P, exhibiting a variable behavior of force reduction and increase with changes in P and γ. Finally, the load formulas, including maximum horizontal force and maximum overturning moment, were modified by quantifying the effects of openings and orientation, supporting hydraulic engineers for the load design of building structures.

Method for identifying the strength characteristics of concrete of a reinforced concrete crossbar during heating under conditions of fire

This paper proposes a method that makes it possible to study the patterns of changes in the concrete strength of reinforced concrete crossbars depending on the heating temperature under fire conditions by interpreting the results of their standard fire tests. For the implementation of this method, it is proposed to use similar data obtained using mathematical modeling based on the finite element method and given material properties, including the curve of concrete strength reduction recommended by the guidelines, as data included in the set of measurement results during fire tests depending on temperature. Such data are time dependences of temperature indicators at individual cross-section points and time dependence of the maximum deflection of the crossbar. The article proposes an interpolation method that makes it possible to set the temperature at any point of the section based on the approximation of the isotherms by parabolas with a variable indicator of their power. A method based on the mathematical interpretation of temperature indicators obtained using the proposed interpolation method and the curve of the dependence of the maximum deflection on time using a deformation model for describing the stress-strain state is proposed to identify the dependence of the concrete strength of reinforced concrete crossbars. The work also shows that the results obtained using the proposed method of identifying concrete strength reduction coefficients are adequate as their relative error is on average no more than 7 %. Based on the results, the possibility of its application to study the regularities of the decrease in the strength of reinforced concrete crossbars under fire conditions has been proven

Determination of groundwater buoyancy reduction coefficient in clay: Model tests, numerical simulations and machine learning methods

Groundwater plays an essential role in stabilizing underground structures. However, hydrostatic uplift forces from groundwater can create safety hazards. This paper obtained the groundwater buoyancy reduction coefficients of 36 types of clays through model tests and conducted a finite element simulation to obtain the buoyancy reduction coefficients of additional clays with varying soil properties. Machine learning methods, including extreme gradient boosting (XGBoost) and random forest (RF) algorithms, were used to analyze and identify the soil parameters that have a significant impact on the reduction of groundwater buoyancy. It was found that the permeability coefficient and saturation are the primary factors that influence the reduction of groundwater buoyancy. Additionally, the prediction models developed by XGBoost and RF were compared, and their accuracy was evaluated. These research findings can serve as a reference for designing underground structures that can withstand the potential risk of buoyancy in clay.

Restaging of rectal cancer with hybrid positron emission tomography magnetic resonance imaging after preoperative chemoradiotherapy.

This study determines the sensitivity and specificity of positron emission tomography/magnetic resonance imaging (PET/MRI) parameters in predicting treatment response in patients with localised rectal cancer who have undergone preoperative chemoradiotherapy (CRT). Patients with stage I-III adenocarcinoma of the rectum planned for preoperative CRT followed by surgery were recruited. Patients had PET/MRI scans at baseline and 6-8 weeks post-CRT. Functional MRI and PET parameters were assessed for their diagnostic accuracy for tumour regression grade (TRG). Nonparametric receiver operating characteristic analysis was employed to determine the area under the ROC curve (AUC), and the sensitivity and specificity of each quantile cut-off. A total of 31 patients were recruited, of whom 20 completed study protocol. All patients included had mid or lower rectal tumours. There were 16 patients (80%) with node-positive disease at presentation. The median time to surgery was 75.5 days (range 52-106 days). Histopathological assessment revealed 20% good responders (TRG 1/2), and the remaining 80% of patients had a poor response (TRG 3/4). When predicting good responders, the AUC values for percent maximum thickness reduction and percent apparent diffusion coefficient (ADC) change were 0.82 and 0.73, respectively. A maximum thickness reduction cut-off of >47% and a percent ADC change of >20% yielded a sensitivity and specificity of 75%/95% and 75%/73%, respectively. Parameters such as percent maximum thickness reduction and percent ADC change may be useful for predicting good responders in patients undergoing preoperative CRT for rectal cancer. Larger studies are warranted to establish the utility of PET/MRI in rectal cancer staging.

Stability bearing capacity of concrete filled steel tubular columns subjected to long-term load

Concrete-filled steel tube (CFST) are commonly used in modern building and bridge applications. Despite their popularity, studies on the investigation of the influence of long-term load on the stability bearing capacity of such elements are scarce. This study investigates how the key parameters including slenderness ratio (λ), axial load ratio (m), and eccentricity ratio (e/r) affect the stability bearing capacity of a CFST column under sustained load. Twenty three CFST columns were fabricated to investigate the effect of long-term load on the stability bearing capacity. Fourteen specimens were subjected to constant compressive loading for 462 days and then tested for failure. The remaining 9 were companion load-free specimens. A three-stage finite element method was used to predict the stability bearing capacity after creep. The results indicate that the stability bearing capacity of CFST columns decrease after being subjected to long-term load. Both the experimental and numerical results indicated that the load of steel tube for long-term load specimens reaching up to the elastic–plastic and plastic process was lower than that of the load-free specimens. Moreover, the corresponding strain of the creep specimens was greater than that of the load-free specimens when the member reached the maximum load. Benchmarking analyses have shown that the creep reduction coefficient (kcr) proposed for CFST columns can be used to predict the reduction of stability bearing capacity after creep. Furthermore, a collected database comprising 49 CFST specimens subjected to long-term load was used to investigate the proposed formulae for kcr. The results show that the formulae were consistent with the experiment results.

Acoustic Characteristics of Jute and Coir Non-woven Fabric

Effective noise reduction is essential because it can influence the health and well-being of living organisms significantly, both physically and psychologically. This necessitates the use of appropriate absorbing materials to minimize the negative impact of noise. In recent years, there has been growing interest in using jute, coir and natural fibre-based acoustic materials in architectural and interior applications due to their exceptional acoustic properties, eco-friendliness, cost-effectiveness and widespread availability. The study focuses on analysing the effects of some scrutinised testing parameters of jute, coir and jute-coir blended non-woven fabric samples on noise reduction coefficient through observing sound absorption coefficient. The sound absorption coefficient was measured using the impedance tube method as per the ASTM E-1050 standard. The mean value of the sound absorption coefficient observed at frequencies 250 Hz, 500 Hz, 1000 Hz, and 2500 Hz was used to calculate the noise reduction coefficient. A three-factor & three-level Box–Behnken experimental design was used for designing research and non-woven jute, coir and jute coir blended fabric sample planning. The experimental work showed that with an increase in non-woven jute fabric sample thickness from 15 mm to 45 mm, blending jute 50 % with coir 50% and non-woven fabric samples tested by creating air gaps (15 mm to 30 mm) resulted in higher sound absorption coefficient and improved noise reduction coefficient. The experimental findings and statistical analysis revealed that blending jute with coir and increasing the thickness of non-woven fabric led to a significant improvement in the acoustic performance of the tested samples. However, increasing the air gap resulted in only a marginal improvement in acoustic performance.

Experimental study and theoretical analysis on lateral stiffness of RC frame-frame truss composite wall

Two reinforced concrete (RC) frame-frame truss composite wall (FTCW) specimens with a scale of 1:2 are implemented for cyclic loading test. The test results of phenomenon, hysteretic curves, backbone curves and stiffness degradation curves are obtained, and the seismic performance of shear capacity, ductility, lateral stiffness are analyzed. The lateral stiffness of RC frame-FTCW and the horizontal displacement are mechanical analyzed, and the results are compared with the test results. The test behaviour shows that a multistage energy consuming system that FTCW works before RC frame and the internal diagonal struts work before the outer frame inside the FTCW, forming a multistage energy consumption system for the design purpose of earthquake resistant structures. The point that the embedded angle steel effectively extend the elastic stage of the internal diagonal struts and the point that the amount of FTCW is proportionateto the shear capacity and lateral stiffness are also concluded by the test results. The comparison results of lateral stiffness between mechanical analysis and test results show that the reduction coefficients in different stages and the mechanical analysis are practical and significant.

Fabrication, sound absorption simulation and performance optimization of multi‐layer gradient fiber‐based composites

AbstractNoise reduction with materials of finite thickness has been a hot research topic. In this study, multi‐layer gradient fiber‐based composites integrating porous, resonant and damping structures were prepared for efficient sound absorption. Here, the effects of composite structure, fiber‐based thickness and micro‐perforated membrane fabric (MPMF) structure on the sound absorption of the composites were investigated. From the results, the sound absorption band of the composite can be effectively tuned by adjusting the structure of the MPMF or the thickness of the fiber‐based. In addition, the established acoustic model can accurately predict the sound absorption performance of the structure. It is worth mentioning that the gradient structure optimized by the algorithm exhibits broadband sound absorption (noise reduction coefficient of 0.42) and thin feature (thickness of 0.9 cm). Moreover, the medium and low frequency sound waves can be propagated and absorbed more easily by optimizing the structure of the composite. This work provides a reference for the preparation of multi‐layer gradient sound‐absorbing structures and the design of acoustic products in a specific frequency range.

Low-rank Representation with Adaptive Dimensionality Reduction via Manifold Optimization for Clustering

The dimensionality reduction techniques are often used to reduce data dimensionality for computational efficiency or other purposes in existing low-rank representation (LRR)-based methods. However, the two steps of dimensionality reduction and learning low-rank representation coefficients are implemented in an independent way; thus, the adaptability of representation coefficients to the original data space may not be guaranteed. This article proposes a novel model, i.e., low-rank representation with adaptive dimensionality reduction (LRRARD) via manifold optimization for clustering, where dimensionality reduction and learning low-rank representation coefficients are integrated into a unified framework. This model introduces a low-dimensional projection matrix to find the projection that best fits the original data space. And the low-dimensional projection matrix and the low-rank representation coefficients interact with each other to simultaneously obtain the best projection matrix and representation coefficients. In addition, a manifold optimization method is employed to obtain the optimal projection matrix, which is an unconstrained optimization method in a constrained search space. The experimental results on several real datasets demonstrate the superiority of our proposed method.

Time dependent analysis of lateral bearing capacity of reinforced concrete piles combined with corrosion and scour

This study investigates the effect of chlorine corrosion and flow scour on the lateral bearing capacity of piles. A chloride diffusion model was established to obtain the initial corrosion time of reinforcement based on Fick's second law. The degradation of stiffness after corrosion is represented by a reduction coefficient. The finite difference method is used to solve the deflection differential equation of laterally loaded piles. The maximum scouring depth of piles in cohesive soil and the variation of scouring depth with time are calculated by empirical model. The calculated results from the analytical solution revealed that the pile stiffness decreases with the exposure time. As the time increase, the lateral displacement and shear force decrease on the other hand the bending moment increases. The increase of flow velocity and pile diameter results in the increase of the maximum scour depth around the pile. The bending moment, shear force, and lateral displacement of piles after scour increase significantly compared to the lateral bearing performance of piles before scour.

Heat-conducting elastic ultrafine fiber sponges with boron nitride networks for noise reduction

Industrial and traffic noise has become increasingly serious with the progress of industrialization. Most existing noise-absorbing materials suffer from poor heat dissipation and insufficient low-frequency (<1000 Hz) noise absorption, which not only reduces working efficiency but also leads to safety risks. Herein, heat-conducting elastic ultrafine fiber sponges with boron nitride (BN) networks were prepared by integrating direct electrospinning and impregnation method. The large acoustic contact area of ultrafine fibers and the vibration effect of BN nanosheets in a three-dimensional direction endow fiber sponges with good noise reduction, which can reduce white noise by 28.3 dB with a high noise reduction coefficient of 0.64. Moreover, thanks to good heat-conducting networks composed of BN nanosheets and porous structures, the obtained sponges exhibit superior heat dissipation with thermal conductivity of 0.159 W m−1 K−1. Besides, the introduction of elastic polyurethane and following crosslinking endow the sponges with good mechanical properties, which have almost no plastic deformation after 1000 compressions, and the tensile strength and strain are as high as 0.28 MPa and 75%. The successful synthesis of heat-conducting elastic ultrafine fiber sponges overcomes poor heat dissipation and low-frequency noise reduction of noise absorbers.

Analysis and Prediction of the Factors Influencing Postconstruction Surface Deformation of Pipe-Jacking Tunnel in Soft Clay Strata in China

During the postconstruction operation period, the engineering structure and operation safety of a pipe-jacking tunnel are more likely to be threatened by the surrounding environment and groundwater when it is located in a soft clay stratum. Surface settlement data related to the construction of 24 rectangular pipe-jacking tunnels in a soft clay stratum in China were collected and analyzed to determine the effect of pipe-jacking tunnel engineering on its deformation based on factors such as structural section form, geotechnical condition, groundwater condition, and buried depth. The postmaximum surface settlement and postformation loss rate were obtained, the correlation coefficients between the postsurface deformation of soft clay strata and various influencing factors were calculated using a software for correlation analysis, and the variation rules for each influencing factor were explored in depth. Subsequently, multiple linear regression methods were used to predict the maximum surface deformation of the pipe-jacking tunnel project in soft clay strata during the postoperation period, and actual engineering cases were verified and analyzed. The results show that the relative buried depth of the pipe-jacking tunnel in soft clay stratum has the greatest influence on the postmaximum ground settlement, followed by the section area of the pipe-jacking tunnel, and the relative height coefficient of groundwater level has the least influence. Under the reduction coefficient of 0.937 − 0.846, a new prediction formula for surface settlement deformation after the construction of the soft clay layer was derived. The error between the formula and the measured data was 9.05%, which can be used as a reference for controlling design parameters to predict the settlement after construction of pipe-jacking engineering.

The Potential of Sawdust and Coconut Fiber as Sound Reduction Materials

In this study, biodegradable materials that could be utilized to reduce noise were examined. Sound absorption test was conducted with an impedance tube. Sawdust, coconut fiber, and expansive clay were used to create test samples. Noise reduction coefficient results for sawdust and expansive clay mixture ranged from 0.24 to 0.62. A mixture of coconut fiber and expansive clay recorded in noise reduction coefficient between 0.31 and 0.58. Coconut fiber mixed with expansive clay recorded noise reduction coefficient ranging from 0.31 to 0.58. The study findings suggests that these materials have good acoustic properties and can therefore be used as alternative noise reduction materials. These findings have important implications in reducing environmental pollution if adopted in the development of noise reducing materials.