Geometry Factors Research Articles

The Interplay of Strongly and Weakly Exchange-Coupled Triplet Pairs in Intramolecular Singlet Fission.

Singlet fission (SF) and triplet-triplet annihilation upconversion (TTA-UC) nominally enable the interconversion of higher-energy singlet states with two lower-energy triplet states and vice versa, with both processes having envisaged application for enhanced solar power devices. The mechanism of SF/TTA-UC involves a complex array of different multiexcitonic triplet-pair states that are coupled by the exchange interaction to varying extents. In this work a family of bounded intramolecular SF materials, based upon the chromophore 1,6-diphenyl-1,3,5-hexatriene, were designed and synthesized. Their SF behavior was characterized using fluorescence lifetime, transient absorption, and magnetic field dependence studies. The capacity for the formation of weakly exchange-coupled triplet pairs, and subsequent spin-evolution, is shown to be strongly dependent upon the combined factors of oligomer size and geometry. By contextualizing these results with the wider SF literature, we present a general schematic model for SF/TTA-UC of greater completeness than portrayed elsewhere.

Analysis of the tooth-root stress of external spur gears with high effective contact ratio

For spur gears with contact ratio close to 2, the extension of the contact interval resulting from loaded tooth deflections and local contact deformations may result in an effective contact ratio above 2. In these cases, the load is transmitted by at least two tooth-pairs, the maximum load and tooth-root stress decrease, and therefore the calculation methods of the gear rating Standards ISO and AGMA provide very conservative results. In this work, two models are applied to the calculation of the tooth-root stress of load-induced high contact ratio external gears: (i) an analytic model of load sharing, based on the minimum energy method, and (ii) a finite element model, which validates the results obtained from the previous model. Obtained values of the stress are compared with those provided by ISO and AGMA rating methods, which do not account for the stress reduction due to the higher contact ratio. A new modification coefficient is proposed to correct these conservative values, which allows the AGMA and ISO geometry factors to remain as no load-dependent factors and keep their actual calculation methods and significance.

The impact of tyre tread pattern design parameters on accelerated pass-by noise

Road-Traffic noise is one of the major environmental issues globally. Considering its effects on human health, international standards have been developed and emission limits have been adopted. In Europe, these regulations are becoming more stringent and challenging the automotive industry. There are two legislative Pass-by-noise test methods: Normal Pass-By-Noise (R117) for Tyre legislation and Accelerated Pass-By-Noise (R51) for vehicle legislation. For OE (Original Equipment) business meeting strict Accelerated Pass-By-Noise target is necessary for the Tyre industry because Tyre is a major influencing factor in overall vehicle noise. This paper explores the relationship between the parameters of tyre tread pattern and their effect on accelerated pass-by noise. The investigation shows how specific characteristics of the tread pattern, such as design, groove geometry, and other relevant factors, contribute to the overall noise generated during accelerated pass-by noise measurements.

Quelling the Geometry Factor Effect in Quantum Chemical Calculations of 13C NMR Chemical Shifts with the Aid of the pecG-n (n = 1, 2) Basis Sets

A root factor for the accuracy of all quantum chemical calculations of nuclear magnetic resonance (NMR) chemical shifts is the quality of the molecular equilibrium geometry used. In turn, this quality depends largely on the basis set employed at the geometry optimization stage. This parameter represents the main subject of the present study, which is a continuation of our recent work, where new pecG-n (n = 1, 2) basis sets for the geometry optimization were introduced. A goal of this study was to compare the performance of our geometry-oriented pecG-n (n = 1, 2) basis sets against the other basis sets in massive calculations of 13C NMR shielding constants/chemical shifts in terms of their efficacy in reducing geometry factor errors. The testing was carried out with both large-sized biologically active natural products and medium-sized compounds with complicated electronic structures. The former were treated using the computation protocol based on the density functional theory (DFT) and considered in the theoretical benchmarking, while the latter were treated using the computational scheme based on the upper-hierarchy coupled cluster (CC) methods and were used in the practical benchmarking involving the comparison with experimental NMR data. Both the theoretical and practical analyses showed that the pecG-1 and pecG-2 basis sets resulted in substantially reduced geometry factor errors in the calculated 13C NMR chemical shifts/shielding constants compared to their commensurate analogs, with the pecG-2 basis set being the best of all the considered basis sets.

Effect of length-to-height ratio on fracture properties of asymmetrical single-edge notched beam (ASENB) specimen made of ceramic under full range mixed mode I/II loading state

Asymmetrical single-edge notched beam (ASENB) specimen is among the suitable specimens for measuring full mode I/II fracture parameters. However, in lack of a standard or common method, researchers used this specimen with different geometers, which have proven can affect the results. This research evaluated the effect of ASENB’s geometry on fracture parameters numerically and experimentally. First, the finite element method determined the geometry factors (YI and YII) and non-singular (T-stress) fracture parameters. Then, the experimental fracture tests were conducted using ceramic material. Results show it is more reasonable to express the YI and YII based on S1/L and S2/H, instant S1/L, and S2/L. In other words, the geometry factors can be expressed better based on the height of the specimen and not length. So, for ASENB specimens tested in conventional S1/L of 0.7 to 0.9, the pure mode-II condition was generated in 0.05 < S2/H < 0.14. The modeling showed that the non-singular term of fracture (T-stress) was significant compared to fracture toughness, so the Biaxiality was measured as 0.5 to −2.5, more significant for pure mode-II and almost regardless of the a/H ratio. As experimental tests show, the relative length of the ASENB specimen has an insignificant effect on measured fracture toughness, so a more compact specimen with L/H of about 2 to 4 can suggested for tests.

Quantification of elemental composition of the thin tissue slices with the commercial benchtop micro-XRF spectrometer

In this paper we present the scheme for quantification of local elemental composition by micro-XRF in thin tissue slices. The proposed procedure involves simultaneous determination of the geometry factor and the primary spectrum distribution from the measurement of set of the thin film calibrations standards. The procedure has been applied for the commercial M4 Tornado Plus spectrometer by Bruker. The quantification of the thin tissue slice has been performed as well.

REVIEW OF PARAMETERS INFLUENCING WIRELESS ENERGY TRANSMISSION BY MAGNETIC INDUCTION

In this review article, we present a detailed study and discussion of wireless energy transfer systems based on studies in the literature, with the help of Python programming software. Starting from the basic element of wireless transmission by magnetic induction, i.e. the coil, through a magnetostatic study we have highlighted the impact of geometry, coil misalignment and coil loss factors on these transmission systems. We have also shown that parameters such as coupling coefficient and frequency can improve transmitted power and efficiency. A summary of the latest research in this field will also be given.

DIGITAL SOLUTION FOR OPTIMIZATION OF FORMATION TESTING DESIGN

Evaluation of pumping time to receive a clean sample during fluid sampling job with wireline formation tester as well as evaluation of pumping scenarios to minimize sampling duration under existing constrains (reservoir and sandface constrains, safety etc.) are actual problems especially for fluid sampling in low-permeability formation. The article describes the digital solution allowing to simulate mud filtrate invasion in near-wellbore zone during well drilling and mud filtrate displacement by reservoir fluid during fluid sampling job with taking into account a formation damage dynamics. In this way, the software is able to evaluate depth of mud filtrate invasion and simulate both the multiphase inflow dynamics and the skin-factor dynamics during sampling job and predict sampling duration. To take into account a complex, essentially non-1D geometry of multiphase fluid flow in near-wellbore zone during fluid sampling, the special upscaling technique was developed. This upscaling technique is based on modification of 1D model by introduction of «effective» mud filtrate invasion profile and «geometry factor» which depend on ratio of vertical to horizontal permeabilities. The correlations between empirical model parameters and ratio of vertical to horizontal permeabilities were obtained by matching results of «pseudo 2D» simulations of pumping dynamics with results of 2D / 3D simulations conducted using commercial simulators ECLIPSE® and COMSOL Multiphysics®. The developed «pseudo 2D» model is computationally fast ones that allows to effectively conduct sensitivity study as well as adjust the model parameters and sampling scenario in real time in accordance with the real-time wireline formation tester measurements.

Getaway from the Geometry Factor Error in the Molecular Property Calculations: Efficient pecG-n (n = 1, 2) Basis Sets for the Geometry Optimization of Molecules Containing Light p Elements.

The basis of all molecular property quantum chemical calculations is the correct equilibrium geometry. In this paper, new efficient pecG-n (n = 1, 2) basis sets for the geometry optimization of molecules containing hydrogen and p elements of 2-3 periods are proposed. These basis sets were optimized via the property-energy consistent (PEC) algorithm directed to the minimization of the molecular energy gradient relative to the bond lengths. New basis sets are compact and give equilibrium geometries of very high quality, which is comparable to that provided by considerably larger energy-optimized basis sets. The equilibrium geometries obtained with the pecG-n (n = 1, 2) basis sets and the other basis sets of diverse quality were tested in the CCSD calculations of different second-order molecular properties, including NMR shielding constants, static polarizabilities, and static magnetizabilities. As a result, new basis sets have demonstrated far superior performance as compared to the other energy-optimized basis sets of the same or close sizes commonly used at the geometry optimization stage.

Hip and pelvic geometry as predictors of knee osteoarthritis severity.

Malalignment is one of the most critical risk factors for knee osteoarthritis (KOA). Biomechanical factors such as knee varus or valgus, hip-knee-ankle angle, and femoral anteversion affect KOA severity. In this study, we aimed to investigate KOA severity predictive factors based on hip and pelvic radiographic geometry. In this cross-sectional study, 125 patients with idiopathic KOA were enrolled. Two investigators evaluated the knee and pelvic radiographs of 125 patients, and 16 radiological parameters were measured separately. KOA severity was categorized based on the medial tibiofemoral joint space widths (JSW). Based on JSW measurements, 16% (n = 40), 8.8% (n = 22), 16.4% (n = 41), and 56.8% (n = 147) were defined as grades 0, 1, 2, 3, respectively. There were significant differences between the JSW groups with respect to hip axis length, femoral neck-axis length, acetabular width, neck shaft angle (NSA), outer pelvic diameter, midpelvis-caput distance, acetabular-acetabular distance, and femoral head to femoral head length (P < .05). Two different functions were obtained using machine learning classification and logistic regression, and the accuracy of predicting was 74.4% by using 1 and 89.6% by using both functions. Our findings revealed that some hip and pelvic geometry measurements could affect the severity of KOA. Furthermore, logistic functions using predictive factors of hip and pelvic geometry can predict the severity of KOA with acceptable accuracy, and it could be used in clinical decisions.

Aromatic salt induced modulations in micellization behavior of amide functionalized surface-active ionic liquids: The role of cationic head group

The present study highlights the effect of aromatic salt i.e. sodium benzoate (NaBz) at fix concentration (1 mM), on the micellization behavior of four amide functionalized surface-active ionic liquids (SAILs) having different cationic head groups in aqueous medium. The adsorption behavior of the SAILs at the air-solution interface has been investigated by tensiometry, where improved surface activity was observed in all the investigated SAILs in the presence of added hydrotrope. The conductivity, steady-state fluorescence, dynamic light scattering (DLS), and zeta-potential measurements have been performed to probe the micellization of the SAILs in bulk solution. The position and orientation of aromatic anion, Bz-, at the micelle-water interface surface has been investigated by 1H NMR spectroscopy. The thermodynamic aspects of micellization have been examined by Isothermal titration calorimetry (ITC). It has been observed that the nature, geometry, and steric factor of the cationic head group of SAILs govern their interactions with Bz- and this influences the characteristic properties of micellization.

Breathing space in a compact city: Impacts of urban re-densification on Mumbai's low-income housing environment

Redevelopment of low-income settlements by re-densifying cities is a common approach in the Global South to improve living conditions and tackle the housing shortage. However, the effectiveness of the housing design in redevelopment schemes remains to be questioned. This study evaluates a proposed design of a slum redevelopment project in Mumbai, India, by comparing the environmental performance of three design schemes: the existing low-income housing, the redevelopment scheme proposed by the local government and a hypothetical design (modified scheme) that aligns with positive environmental outcomes identified in the current literature. The environmental factors such as the natural airflow, incident solar radiation and daylighting parameters were assessed by computational simulations and validated by a wind tunnel experiment. These factors were associated with direct and indirect density metrics of the three design schemes to inform better policymaking for slum redevelopment projects that seek to re-densify housing for the urban poor. The results indicated that the design performance of the redeveloped scheme is less preferable due to the unclean indoor air and inadequate daylighting conditions requiring large-scale demolition of the existing buildings. The modified plan requires minimal demolishment and demonstrates relatively better environmental performance. The study revealed that indirect density measures - building geometry factors and urban form parameters - are essential in affecting the ecological performance of housing. Considering these factors in design standards and policymaking for high-density redevelopment schemes can enable the “Goldilocks density” that significantly improves the quality of living while densifying the cities.

Three-row MRI receive array with remote circuitry to preserve radiation transparency

Objective. Up to this point, 1.5 T linac-compatible coil array layouts have been restricted to one or two rows of coils because of the desire to place radiation-opaque circuitry adjacent to the coils and outside the window through which the linac beam travels. Such layouts can limit parallel imaging performance. The purpose of this work was to design and build a three-row array in which remotely located circuits permitted a central row of coils while preserving the radiolucent window. Approach. The remote circuits consisted of a phase shifter to cancel the phase introduced by the coaxial link between the circuit and coil, followed by standard components for tuning, matching, detuning, and preamplifier decoupling. Tests were performed to compare prototype single-channel coils with remote or local circuits, which were followed by tests comparing two and three-row arrays . Main results. The single-channel coil with the remote circuit maintained 85% SNR at depths of 30 mm or more as compared to a coil with local circuit. The three-row array provided similar SNR as the two-row array, along with geometry factor advantages for parallel imaging acceleration in the head–foot direction. Significance. The remote circuit strategy could potentially support future MR-linac arrays by allowing greater flexibility in array layout compared to those confined by local circuits, which can be leveraged for parallel imaging acceleration.

Microscopic fracture toughness of notched porous sintered Cu micro-cantilevers for power electronics packaging

To fulfill the high-temperature application requirement of high-power electronics packaging, Cu nanoparticle sintering technology, with benefits in low-temperature processing and high-melting point, has attracted considerable attention as a promising candidate for the die-attach interconnect. Comprehensive mechanical characterization of the sintered layer at a microscale is necessary to deepen the understanding of the fracture behavior and improve the reliable design of materials. In this study, microscale cantilevers with different notch depths were fabricated in a 20 MPa sintered interconnect layer. Continuous dynamical fracture testing of the microcantilevers was conducted in situ in a scanning electron microscope to detail the failure characteristic of the porous sintered structure. The microscopic fracture toughness of different notched specimens was obtained from the J-integral in the frame of elastic-plastic fracture mechanics. Specimens with deeper notches presented higher resistance to crack extension, while geometry factors of notch-to-width ratio between 0.20 and 0.37 exhibited a relatively stable microscopic fracture toughness ranging from 3.2 ± 0.3 to 3.6 ± 0.1 MPa m1/2.

On the utmost importance of the geometry factor of accuracy in the quantum chemical calculations of 31P NMR chemical shifts: New efficient pecG-n (n = 1, 2) basis sets for the geometry optimization procedure.

31P nuclear magnetic resonance (NMR) chemical shifts were shown to be very sensitive to the basis set used at the geometry optimization stage. Commonly used energy-optimized basis sets for a phosphorus atom containing only one polarization d-function were shown to be unable to provide correct equilibrium geometries for the calculations of phosphorus chemical shifts. The use of basis sets with at least two polarization d-functions on a phosphorus atom is strongly recommended. In this paper, an idea of creating the basis sets purposed for the geometry optimization that provide the least possible error coming from the geometry factor of accuracy in the resultant NMR shielding constants is proposed. The property-energy consisted algorithm with the target function in the form of the molecular energy gradient relative to P-P bond lengths was applied to create new geometry-oriented pecG-n (n = 1, 2) basis sets for a phosphorus atom. New basis sets have demonstrated by far superior performance as compared to the other commonly used energy-optimized basis sets in massive calculations of 31P NMR chemical shifts carried out at the gauge-including atomic orbital-coupled cluster singles and doubles/pecS-2 level of the theory by taking into account solvent, vibrational, and relativistic corrections.

Assessing the effects of geometry and non-geometry related factors in work-zone crashes

Objective Work zones are unique in geometry and traffic management, utilizing special traffic signs, standard channelizing devices, appropriate barriers, and pavement markings. These configurations can introduce unexpected driving conditions, potentially posing risks to drivers. This analysis aims to explore potential differences in contributing factors between work-zone crashes where geometry was identified as a factor and those where it was non-geometry factor. To gain insights into driver injury severities in single-vehicle work-zone crashes, this study analyzed work zone crash data from Florida. Method This study employed random parameters logit models, accommodating potential variations in parameter estimates’ means and variances. The dataset encompassed a wide array of factors known to influence driver injury severity, encompassing crash characteristics, vehicle attributes, roadway features, prevailing traffic volume, driver profiles, and spatial and temporal considerations. Results This analysis yielded significantly distinct parameters for work-zone crashes, distinguishing between geometry-related and non-geometry-related factors (primarily the human factors). This distinction suggests a complex interplay between these factors. Notably, the marginal effects of individual parameter estimates exhibited marked differences between these two categories – geometry and non-geometry factors. Conclusion These findings contribute to the growing body of research indicating that geometric restrictions within work zones introduce a distinct set of risk factors compared to non-geometry-related factors. Recognizing the significance of geometric restrictions, beyond typical driving conditions, holds the implications for enhancing safety within various work zone configurations and offers valuable insights for crash scene investigators to pinpoint contributing factors accurately.

Muscle geometry and its relevance for sports performance? A perspective of current findings and future opportunities

Muscle geometry and its relevance for sports performance? A perspective of current findings and future opportunities

A simplified fracture mechanics method for fatigue life analysis of weld roots

Volvo CE currently uses the effective notch stress method for assessing fatigue life in welded structures. For large structures such as frames, a sub modelling technique with a very fine mesh is necessary using millions of DOF. Stress tensors from unit load cases, estimated with FEA, are combined with time history loading from Multi Body Simulations of the complete machine operating on customer representative digitized test tracks. A critical plane approach (the Modified Wöhler Curve Method) is used to estimate the fatigue life. The usage of the effective notch method implies a very time-consuming design process. An LEFM approach for weld roots would be even more time-consuming but would be a more natural approach since the weld root consists of crack like defects. To overcome the drawbacks with the current design process that involves usage of the effective notch method, a hybrid method is defined using pre-calculated geometry factors for different crack sizes and weld geometries. The geometry factors as a function of crack size, and the weld geometry, are stored in a database. From the unit load cases the structural stress using a coarse mesh in the weld is extracted. Together with the geometry factors, the stress intensity factors may be estimated and used with Paris law to calculate the fatigue life of welds. A comparison between the effective notch method, LEFM and the new hybrid method is carried out for typical fillet welds is presented in this paper.

Influence of Curve Geometry Factors on Driver’s Speed Decision Making When Passing through a Horizontal Curve

Influence of Curve Geometry Factors on Driver’s Speed Decision Making When Passing through a Horizontal Curve

Street Design Strategies Based on Spatial Configurations and Building External Envelopes in Relation to Outdoor Thermal Comfort in Arid Climates

Climate change patterns and expected extreme weather conditions drive urban design practices toward more effective adaptation strategies for the built environment. Biskra City, one of the largest urban areas in the Algerian Sahara territory, has suffered from unprecedented extreme weather patterns, specifically during the summer. This paper examined outdoor thermal comfort in the arid climates of Biskra, Algeria, during summer extreme conditions by investigating the impact of the height-to-width (H/W) ratio aspect and the north–south (N-S) and east–west (E-W) street orientations on pedestrian thermal comfort with the parameterization of external building envelopes using brick, concrete, adobe, and limestone materials. This study was conducted with ENVI-met 5.1.1 software, based on 24 parametric scenarios, to identify the most effective composition for outdoor thermal stress mitigation using the physiological equivalent temperature (PET) thermal index. Across all scenarios, the PET index values fluctuated between PETmin = 32.2 °C and PETmax = 60.6 °C at different hours. The coupling between the H/W ratio and street orientation as geometry factors and building envelope characteristics reveals six distinct categories of building materials, each with an impact on outdoor thermal comfort: (1) high cooling (60–100%), (2) medium cooling (40–60%), (3) low cooling (&lt;40%), (4) high heating (60–100%), (5) medium heating (40–60%), and (6) low heating material (&lt;40%). Therefore, in the N-S orientation, limestone walls can provide a cooling efficiency range from 85% to 100% throughout deep and shallow canyons. Contrary to this, brick walls can cause a heat retention range varying from 70% to 93% within the same canyons. When considering extreme summer conditions in arid climates, the results show that the most effective bioclimatic passive strategy that could be achieved is the E-W orientation, within H/W &lt; 1, characterized by a high albedo building material.