Exponential Relationship Research Articles

A High Throughput Platform to Minimize Voltage and Fill Factor Losses

AbstractOrganic photovoltaics (OPV) now can exceed 20% power conversion efficiency in single junction solar cells. To close the remaining gap to competing technologies, both fill factor and open‐circuit voltage must be optimized. The Langevin reduction factor is a well‐known concept that measures the degree to which charge extraction is favored over charge recombination. It is therefore ideally suited as an optimization target in high‐throughput workflows; however, its evaluation so far requires expert interaction. Here, an integrated high‐throughput workflow is presented, able to obtain the Langevin reduction factor within a few seconds with high accuracy without human intervention and thus suited for autonomous experiments. This is achieved by combining evidence from UV–vis spectra, current–voltage curves, and a novel implementation of microsecond transient absorption kinetics allowing, for the first time, the intrinsic determination of charge absorption cross‐sections, which is crucial to reporting stationary charge densities. The method is demonstrated by varying the donor:acceptor ratio of the high performance OPV blend PM6:Y12. The high reproducibility of the method allows to find a strictly exponential relationship between the PM6 exciton energy and the Langevin reduction factor.

Joint k-b space diffusion-weighted image reconstruction and apparent diffusion coefficient fitting for diffusion-weighted turbo-spin-echo imaging.

Diffusion-weighted (DW) turbo-spin-echo (TSE) imaging offers improved geometric fidelity compared to single-shot echo-planar-imaging (EPI). However, it suffers from low signal-to-noise ratio (SNR) and prolonged acquisition times, thereby restricting its applications in diagnosis and MRI-guided radiotherapy (MRgRT). To develop a joint k-b space reconstruction algorithm for concurrent reconstruction of DW-TSE images and the apparent diffusion coefficient (ADC) map with enhanced image quality and more accurate quantitative measurements. The joint k-b reconstruction model was formulated as an optimization problem subject to a self-consistency condition comprising the exponential decay relationship between DW images and the ADC map. The objective function included a data fidelity term confirming an agreement between the reconstructed images and measured k-space data, incorporating the mono-exponential decay relationship between DW images and ADC map as a constraint, along with spatial regularization terms on both amplitude and phase images. The optimization problem was solved using the alternating-direction method of multipliers (ADMM). We evaluated the performance of the joint reconstruction (JR) algorithm for DW-TSE in a phantom study and patient studies on five brain and head/neck cancer patients. Image distortion, accuracy, and repeatability of ADC measurements were assessed and compared with those from conventional Fourier-transformed (FFT)-based reconstruction and magnitude-based ADC fitting methods, as well as with the clinically used DW-EPI technique. The proposed joint k-b reconstruction method demonstrated improved SNR and enhanced accuracy of ADC measurements in DW-TSE compared to the conventional method. Additionally, JR-DW-TSE with fewer averages at high b-values provided better image quality than the conventional FFT-reconstructed DW-TSE with full averages. The proposed joint k-b reconstruction method for DW-TSE has the potential to deliver distortion-robust diffusion-weighted MRI (DWI) for clinical applications, which is particularly crucial for MRgRT.

Ablation pressure evolution and applicability of exponential laws in laser ramp compression

The laser ablation pressure is often estimated by an exponential scaling law, which is determined by integral averaging of 1–2 ns short pulses. Here, we report a direct, continuous measurement of ablation pressure of a 3–10 ns ramp 351-nm laser pulse. Aluminum is deposited on LiF window, ablation pressure is inferred from the particle velocity of interface using the backward integration method, combined with incident ramp shaped laser intensity, and the real-time laser-driven ablation pressure as a function of incident laser power density on an aluminum target is obtained. For the same ablation pressure scale, when intensity is higher than 1TW/cm2, the surface illuminated intensity of laser should be modified with the cosine of incident angle, which agrees well with the modified Manheimer model [Scheiner and Schmitt, Phys. Plasmas 26(2), 024502 (2019)]. On the other hand, the incidence angle has the least effect when the intensity is below 0.1 TW/cm2. In the range of 0.1–1 TW/cm2, a significant loss in ablation pressure is observed, deviating notably from the exponential scaling relationship. This characteristic makes the laser direct drive ramp loading technique unfriendly to elastoplastic and phase transition problems.

An Extended Fitts’ Law Model for Hand Interaction Evaluation in Virtual Reality: Accounting for Spatial Variables in 3D Space and the Arm Fatigue Influence

Fitts’ law is a standard tool for assessing user performance and interaction device effectiveness in human-computer interaction (HCI). However, it disregards spatial variables in 3D space and arm fatigue impacts. To address these limitations in evaluating hand interaction performance in virtual reality (VR), a target pointing and acquisition experiment was conducted in which two mapping principles of hand movements (translation, angular rotation) and two interaction methods (hand controller, freehand) were compared. The results indicated that (1) in target acquisition, azimuth and inclination angles exhibited a sinusoidal relationship with hand movement time (MT); (2) arm fatigue significantly affected MT, demonstrating an exponential relationship with task duration; (3) in the case of translational movement mapping, freehand interaction exhibited less influence from fatigue compared to controller interaction; while (4) in the angular rotation mapping case, controller pointing demonstrated greater stability, with fewer declines in efficiency than freehand pointing. Based on the findings, new model formulations were developed to accommodate varying conditions.

Study on the Microstructure and Permeability Characteristics of Tailings Based on CT Scanning Technology

The permeability characteristics of tailings directly affect the position of the infiltration line of the tailings dam, which is the most critical factor affecting tailings dam failures. In order to fully analyze the essence of its permeability characteristics, computed tomography (CT) technology is used to analyze the structure of different types of tailings from a microscopic perspective and carry out microscopic seepage simulation. The results showed the following findings: (1) The porosity of viscous tailings ranges from 25 to 35%, the distribution of surface porosity along the height is relatively uniform, and the distribution is shown as having a certain discrete nature with the increase in particle size. (2) Compared with silty and sandy tailings, the surface of viscous tailings is smoother and more round, and the shape factor can reach 0.95; (3) The data gap between the simulation and the measurements by CT scanning technology is less than 10%, and the estimation of the permeability characteristics is feasible, with good applicability in the simulation of tailings seepage. (4) In the microscopic pore throat structure, the permeability characteristics of the tailings are more affected by the radius of the throat than the pore radius, and the exponential function relationship between the permeability coefficient and the porosity satisfies a high correlation. In this paper, the relationship between the microstructure and permeability characteristics of tailings is analyzed by CT technology; the permeability is simulated and calculated, and a permeability coefficient prediction model for tailings is proposed in combination with the experiment, which can provide a new idea and method for the study of the permeability characteristics of tailings.

Visualization study of the effects of polycarboxylates on CO2 hydrate generation and interfacial property.

Marine carbon sequestration, with its high potential and low risk of leakage, is an attractive technology for effectively addressing global climate change and reducing greenhouse gas emissions. A current concern about marine sequestration lies in the potential negative effects of the carbon sequestration process on the marine environment. CO2 hydrate sequestration is considered to be one of the most stable method of sequestration, and researchers are actively searching for promoters that facilitate hydrate sequestration and are friendly to the marine environment. Therefore, the development and utilization of environment-friendly promoters are of great significance for marine carbon sequestration by the hydrate method. In this study, two novel kinetic promoters, polycarboxylates (SP-409 and SPC-100), were applied. The changes in kinetic properties of CO2 hydrate generation and gas-liquid interfacial properties were investigated under different promoter types and concentrations, temperatures, and pressures. Visual observation reveals that the formation of hydrate first occurs at the gas-liquid interface and on the reactor wall, then gradually starts to diffuse into the interior of the solution, forming a white cylindrical solid with a hollow interior. After a comprehensive comparison of temperatures, pressures, and concentrations, the SP-409 solution promoted hydrate generation better than the SPC-100 solution, and the optimal promotion concentration was 1000ppm. In addition, there is an exponential relationship between the rate of hydrate formation and interfacial tension (IFT), which means that the rate of hydrate generation can be quickly estimated from the interfacial tension data at a certain temperature and pressure.

Research on the Non-Uniform Temperature Field Distribution of Q355B Steel for Grain Storage under Fire Conditions

To reveal the distribution characteristics of the non-uniform temperature field of structural steel under fire conditions, Q355B steel for grain storage was taken as the research object. A multi-channel temperature detection instrument was used to monitor the temperature distribution of Q355B test plate in real time under gas fire, and the distribution characteristics of the non-uniform temperature field of the steel were studied under different heat inputs. The results showed that the temperature changes within 600 mm from the flame point were significant, while the temperature changes beyond 600 mm were not sensitive. The peak temperature Tmax and the heating rate vr at the fire source points of each test plate increased linearly with the increase of heat input Q at the fire source. With the increase of distance d, the variation trend of the time tmax for each test plate to reach the peak temperature in the rolling direction, was the same. As d increased, tmax gradually increased and tended to stabilize. The average cooling rates vd1 and vd2 of each test plate decreased with the increase of d. The temperature distribution patterns of each test plate were the same. The Tmax-d curve of each test plate followed the Boltzmann function distribution, the Q-∆T followed a linear relationship, and the Q-d0 followed an exponential function relationship. By combining the three, a non-uniform distribution model of Tmax-Q temperature field under gas fire was obtained.

The Coupled Thermal Response Analysis of Green Roofs Based on the Discrete Element Method

As an effective energy-saving measure, green roofs significantly improve the thermal environment of buildings by covering the roof with vegetation and soil. This paper compares the thermal transfer performance of concrete roofs and green roofs under different temperature conditions. First, a uniaxial compression discrete element method (DEM) was used to calibrate the mesoscopic parameters of concrete, ensuring an accurate representation of concrete properties. The results indicate that green roofs have significant insulation effects under high-temperature conditions in summer. After being exposed to high temperatures for 5 h, the temperature of the green roof was 23.4 degrees Celsius lower than that of the ordinary concrete roof. In addition, different initial temperatures of the model also have a certain impact on heat transfer. The higher the initial temperature, the slower the temperature increase under high-temperature conditions. In winter, the green roof significantly delays the cooling at the top of the building, demonstrating excellent thermal insulation performance. The maximum temperature difference compared with the concrete roof is 8 °C. Finally, there is an exponential relationship between the thermal resistivity of the green roof and the temperature. In conclusion, green roofs have significant energy-saving and environmental protection value.

Analysis of the Relationship Between Groundwater Dynamics and Changes in Water and Salt in Soil Under Subsurface Pipe Salt Drainage Technology

Groundwater conditions are crucial for understanding the evolution of soil salinization. The installation of subsurface pipes significantly alters both the distribution of water and salt in the soil and the groundwater depth; these dynamics and their interrelationships warrant further investigation. To clarify the relationship between groundwater dynamics and changes in water and salt in soil under subsurface pipe salt drainage conditions in the Yinchuan region of Ningxia, groundwater observation wells and soil sample monitoring points were established in Pingluo County. A combined approach of in situ monitoring and laboratory testing was employed to analyze changes in groundwater depth and salinity and their effects on water and salt in soil. The findings revealed that changes in groundwater depth and salinity exhibited clear seasonal patterns. The groundwater depth was deepest at 1.97 m in October and shallowest at 1.62 m in July. The salinity was highest at 22.28 g/L in April and lowest at 18.24 g/L in August. In summer, the groundwater was shallower and had lower salinity, while in other seasons, it was deeper with higher salinity. Soil salinity was lowest in July at 4.58 g/kg and highest in April at over 5.5 g/kg. It decreased with increasing groundwater depth, demonstrating a linear relationship. Additionally, soil salinity and groundwater salinity exhibited synchronous fluctuations, exhibiting an exponential relationship. Based on these observations, a model was developed to describe the relationship among groundwater salinity, groundwater depth, and soil salinity under subsurface pipe salt drainage conditions in the Yinbei region of Ningxia. This model was validated against measured data, yielding a correlation coefficient R2 of 0.7238. These findings provide a reference for analyzing the relationship between soil salinity and groundwater in similar regions.

Association between lactate determined at emergency department arrival and the probability of inhospital mortality and intensive care admission in elderly patients.

Elderly patients often have atypical clinical presentations. Lactate measurement on arrival at the Emergency Department (ED) could be useful to identify elderly patients with a bad prognosis. The study aimed to investigate the relationship between serum lactate determined at ED arrival and the probability of inhospital mortality and intensive care (ICU) admission in elderly patients. Retrospective multipurpose registry. Secondary analysis of the EDEN cohort (Elderly Department and Elder Needs). All patients ≥65 years attending 52 Spanish EDs during 2 week and in whom serum lactate was determined at ED arrival. The relationship between serum lactate values and the risk of inhospital all-cause death and transfer from the ED to the ICU was assessed by unadjusted and adjusted logistic regression assuming linearity and restricted cubic spline models assuming nonlinearity. The cohort included 25 557 patients. The 3024 patients in whom lactate was measured were analyzed. The median age was 81 years (74-87), 1506 (27.2%) were women, 591 (19.5%) had serious comorbidities, 475 (15.7%) severe dependency, and 648 (21.4%) dementia. Death occurred during hospitalization in 217 patients (7.2%) and 53 patients (1.75%) were admitted to the ICU. Serum lactate values were nonlinear related to inhospital mortality and ICU admission. Serum lactate >3.1 mmol/L [odds ratio (OR): 1.60, 95% confidence interval (CI): 1.02-2.50] for inhospital mortality and 3.2 mmol/L (OR: 2.83, 95% CI: 1.03-6.79) for ICU admission were associated with significantly increased ORs in the adjusted models. Serum lactate measured at ED arrival has a significant and exponential relationship with inhospital mortality and ICU admission in elderly patients.

Simulation of the Steady Mixing State of Black Carbon With a Two‐Dimensional Sectional Model

AbstractBlack carbon (BC) strongly absorbs solar radiation and has a warming effect on the earth‐atmosphere system. BC experiences continuous aging, making its optical properties a great uncertainty due to the complex mixing state. To address this issue, we developed a sectional model which is capable of tracking both the aerosol size and the BC core size. This model was applied to simulate BC aging process. The atmospheric observational data from a slightly polluted case was employed to drive the model. It is shown that BC's characteristics tend to reach a steady state within 12 hr. Our analysis reveals that, in the steady state, the size distribution of BC‐containing particles demonstrates a notable characteristic: the particle size distribution decreases exponentially as the particle size increases. This exponential relationship provides a simplified yet accurate representation of the complex BC mixing state. This steady‐state size distribution of BC‐containing particles is validated across diverse atmospheric conditions.

Generalized Ghost Pilgrim Dark Energy in Brans–Dicke Theory

This paper aims to investigate, how the Bianchi Type-V cosmological model can be solved using the generalized ghost pilgrim dark energy postulated by the Brans-Dicke theory of gravitation (Phys. Rev.124, 925 1961). To discover the answers, we rely on the assumptions of (i) the correlation between metric potentials and (ii) the exponential relationship between scale factor and scalar field. The generalized ghost pilgrim dark energy model has been found to be correlated with the polytrophic gas dark energy model. A few physical quantities have been used to explain the solutions' physical behavior.

Deterioration characterization of sandstone physical and mechanical properties under mining and water action

Mining geological disasters occur frequently in Guizhou, with mine mining and rainfall-induced avalanche geological disasters mainly, the investigation concluded that the hard rock of the overlying slide body is mostly sandstone, and it is crucial to study the physical and mechanical properties of sandstone under the action of mine mining (hereinafter referred to as the action of mining) and water action. The paper analyzes the deterioration characteristics of sandstone hydrophysical and mechanical properties under the action of mining and water. The main research results are as follows: (1) The water absorption rate of sandstone increased by 0.056% under the action of mining, the water absorption rate of sandstone increased with a good exponential relationship under the action of dry and wet cycles, the swelling rate of sandstone increased by 0.3% under the action of mining, and the index of disintegration resistance decreased by 0.3% in 5 cycles; (2) The damage rate of uniaxial compressive strength of sandstone after being subjected to mining was 6.367%. The total deterioration rate increases with the number of wet and dry cycles, the stage deterioration rate and the average stage deterioration rate first decrease and then increase, and the degree of fragmentation gradually increases; (3) According to the microscopic test results, the microstructural evolution of “mining cracking → water adsorption → water–rock interaction” model was established.

KATP channel–dependent electrical signaling links capillary pericytes to arterioles during neurovascular coupling

The brain has evolved mechanisms to dynamically modify blood flow, enabling the timely delivery of energy substrates in response to local metabolic demands. Several such neurovascular coupling (NVC) mechanisms have been identified, but the vascular signal transduction and transmission mechanisms that enable dilation of penetrating arterioles (PAs) remote from sites of increased neuronal activity are unclear. Given the exponential relationship between vessel diameter and blood flow, tight control of arteriole membrane potential and diameter is a crucial aspect of NVC. Recent evidence suggests that capillaries play a major role in sensing neural activity and transmitting signals to modify the diameter of upstream vessels. Thin-strand pericyte cell bodies and processes cover around 90% of the capillary bed, and here we show that these cells play a central role in sensing neural activity and generating and relaying electrical signals to arterioles. We identify a KATP channel-dependent neurovascular signaling pathway that is explained by the recruitment of thin-strand pericytes and we deploy vascular optogenetics to show that currents generated in individual thin-strand pericytes are sent over long distances to upstream arterioles to cause dilations in vivo. Genetic disruption of vascular KATP channels reduces the arteriole diameter response to neural activity and laser ablation of thin-strand pericytes eliminates the KATP-dependent component of NVC. Together, our findings indicate that thin-strand pericytes sense neural activity and transform this into KATP channel-dependent electrometabolic signals that inform upstream arterioles of local energy needs, promoting spatiotemporally precise energy distribution.

MSCVI: An improved algorithm for mitigating LiDAR noise and occlusion effects in field wheat tiller number calculation

Tiller number is a key agronomic trait of the crop population, reflecting the adaptability of crop to the environment and the status of plant growth, as well as grain yield. As a state-of-the-art form of active remote sensing that penetrates the vegetation canopy and provides a detailed representation of 3D structures, terrestrial laser scanning (TLS) is beginning to show great potential in precisely counting the tiller number. However, current research of TLS-derived wheat canopy tiller number is commonly affected by mutual occlusion among plants and noise problem. In this study, we proposed a novel Mean Shift Clustering algorithm based on Voxel Interpolation (MSCVI) to effectively mitigate those effects by removing excess noise and interpolating unsampled voxels. The findings demonstrated that there was a strong exponential relationship between the gap fraction (Pgap) and point cloud density for wheat plots. In addition, MSCVI was effective to count the tiller number of wheat under different field treatments (R2 = 0.69, RMSE = 79 tilllers/m2), producing better results than previous adaptive layering and hierarchical clustering (ALHC) algorithm. MSCVI could obtain more precise and detailed wheat canopy information by denoising and compensating the point cloud data, which greatly improved the accuracy of detecting tiller numbers under the condition of high plant density, planophile plant type and tiller stage data. This study provides new insights into effectively mitigating noise and occlusion between plants and within dense canopies, and has potential for accurate calculation of the tiller number in the assessment of crop yield phenotype.

Accelerating upper crustal deformation and seismicity of Campi Flegrei caldera (Italy), during the 2000–2023 unrest

Campi Flegrei is the largest active caldera in Europe and it is home to more than 350,000 people. Since 2005, the caldera has shown accelerating ground inflation and an intensification of seismic activity. Here we quantify the decadal accelerating trend alongside oscillations of various frequencies and explore the relationships between deformation and seismic activity over the period 2000 to November 2023. Results highlight the major changes that have occurred in the last four years analyzed and reveal a parabolic increase in vertical uplift and a super-exponential (squared-exponential) rise in the number of earthquakes and seismic energy release. Inspection of data indicate a close temporal correlation between deformation rate and seismicity, and an exponential relationship, with an exponent increasing over time, between ground deformation and cumulative number of earthquakes. These relationships are consistent with a quasi-elastic behavior and a stress memory (Kaiser) effect of the upper crust of the caldera under an increasing stress suggesting a progressive mechanical weakening. Most importantly, they provide evidence of an accelerating sensitivity of seismic activity to caldera inflation and warn of the possibility of significant seismic events in case of continuation, with the same trends and relations, of the bradyseismic crisis in the next years.

Nonlinear effects of board size and board independence on corporate sustainability performance: international evidence

Purpose This study aims to examine the nonlinear effects of board size and board independence on the corporate sustainability performance of listed firms worldwide. Design/methodology/approach This study uses the global environmental, social and governance (ESG) dataset from the Thomson Reuters database, which includes a sample of 23,766 firm-year observations from 33 countries from 2011 to 2022. Findings The results indicate that board size and independence have positive impacts on corporate sustainability performance; however, these relationships are nonlinear. The authors find an inverted U-shaped relationship for board size. After the optimal point, the positive relationship between board size and corporate sustainability performance becomes negative. Board independence, however, has a positive exponential relationship in which the positive effect increases exponentially after the optimal point. The results are robust to a battery of tests, including alternative measures for corporate sustainability performance, board independence and different estimation procedures. Research limitations/implications This study illustrates empirical evidence on the nonlinear effect of board size and board independence on corporate sustainability performance, which explains the mixed evidence involving board size and independence in corporate sustainability literature and offers a complementary research approach in the literature on board dynamics. Practical implications This study has practical implications for investors aiming for sustainable and ethical investment choices, as they should be mindful of matters relating to board composition, particularly the appointment of independent directors and ideal board size. Originality/value Extensive empirical evidence has examined the relationship between corporate governance variables and corporate sustainability performance. This study introduces the effect of the nonlinear relationship between board size and board independence on corporate sustainability performance using international evidence.

Effect of Pore Water Pressure Ratio on Stability of Wind Turbine Shallow Foundations on Saturated Sandy Soil Due to Soil Liquefaction: A Case Study in Coastal Area of Soc Trang Province, Vietnam

Wind turbines are structures whose operation is always affected by dynamic loads. Currently, shallow foundations are common for onshore wind turbines. In the case of saturated sandy soils, dynamic stresses caused by wind turbines can cause the sand to liquefy or reduce its shear strength due to increased excess pore water pressure (ΔU). The pore water pressure ratio (Ru = ΔU/σ’) is now often used to evaluate the effect of ΔU on foundation stability. This paper presents a method for determining Ru and establishing equations to determine the shear strength of saturated sand from Ru. From there, it is possible to estimate the bearing capacity of the foundation on saturated sand (q’ult), taking into account the effect of the pore water pressure ratio. Using the concept of influence factor of liquefaction (Finf), this paper proposes a procedure to evaluate the effect of pore water pressure ratio on the stability factor of shallow foundations on saturated sandy soil. Applying the above method to the coastal area of Soc Trang province, Vietnam shows that the values of q’ult and Ru are inverse exponential relationships while Finf and Ru are exponential relationships. In particular, q’ult and Finf have a very close correlation with Ru and can be expressed as the following expression: Finf=0.9907e3.56Ru; q’ult = 44450e-3.56Ru.

Nighttime Lights and Population Variations in Cities of South/Southeast Asia: Distance-Decay Effect and Implications

Urbanization in South and Southeast Asia is accelerating due to economic growth, industrialization, and rural-to-urban migration, with megacities like Mumbai, Delhi, and Jakarta leading the trend. By analyzing VIIRS nighttime satellite data from 323 cities across 17 countries, we investigated the relationship between nighttime light (NTL) brightness and population density at varying distances from city centers. Our findings reveal a significant distance-decay effect, with both the intensity of NTL brightness and the strength of the NTL-population density relationship decreasing as the distance from city centers increases. A clear negative exponential relationship with the highest R2 was observed between NTL brightness and the distance from the city center. Our analysis indicates that a 105 km radius most effectively captures the extent of major metropolitan areas, showing a peak correlation between NTL brightness and population density. Cities like Delhi and Bangkok exhibit high NTL brightness, reflecting advanced infrastructure, while mountainous or desert cities such as Kabul and Thimphu show lower brightness due to geographical constraints. These results highlight the importance of adaptive urban planning, infrastructure development, and sustainability practices in managing urbanization challenges in South and Southeast Asia.

Development of an integrated model for environmentally and economically sustainable and smart cities

This research introduces a novel integrated approach for smart cities designed to enhance environmentally sustainable economies through innovations and socio-economic transitions. The model is uniquely and comprehensively developed to create a novel smart city index by integrating 32 performance indicators that notably transform the environment, economy, energy, social, governance and transportation dimensions. The present multidisciplinary conceptual model explores the intersection and cross-sectorial impacts in the quest to potentially achieve a smart city. The assessment methodology employs multi-criteria decision-making and principal component analysis to quantify results and visualize a helpful outcome. Geometric weighting schemes were also used to test the robustness of the model. The model is applied to 20 cities worldwide to determine the smart city index for each city. The smart city index is a composite index that considers smart health as a critical factor for humanity. The correlation between the society and economy indexes shows a significant positive exponential relationship. Enhancing the society index will result in potential economic growth for cities. The trend is supported by a relatively high degree of agreement.