Gap Ratio Research Articles

Ecological Efficiency Measurement and Technical Heterogeneity Analysis in China: A Two-Stage Three-Level Meta-Frontier Network Model Based on Segmented Projection

Due to persistent technological impacts on ecological efficiency (eco-efficiency) and variations in economic power and resource endowments among regions, considering regional and temporal heterogeneity becomes imperative. Ecosystems, often divided into economic production and environmental governance stages, necessitate a holistic assessment incorporating regional, temporal heterogeneity and stage distinctions. To address potential issues of a technology gap ratio (TGR) exceeding 1 within a two-stage network structure with dual heterogeneity, we introduce a segmented projection three-layer meta-frontier analysis method. In empirical study, we systematically examined eco-efficiency, emissions inefficiency and technology gaps across management, regional and temporal dimensions in 30 Chinese provinces from 2016 to 2020. Findings reveal disparities in management eco-efficiency, with the central provinces outperforming the east. Regional differences indicate advanced technology in the east, contributing to superior eco-efficiency. Temporal analysis highlights the positive role of scientific and technological development. Emissions inefficiency improvements are noted, necessitating attention toward management and regional technology levels. Eastern provinces exhibit superior emissions efficiency, emphasizing the role of regional and technological development. Recommendations include prioritizing environmental governance, strengthening regional collaborations and implementing policies to bridge technology gaps.

An experimental investigation of the flow control of a circular cylinder in near wake with parallel plates at Re = 7500

The vortex street suppression in the near wake region of the cylinder with parallel plates was investigated using particle image velocimetry (PIV) at Reynolds number of Re = 7500. The rigid plates are designed as flat, parallel with the free-stream direction, and located on both sides of the cylinder. Two different plate lengths (0.5D and 1D based on the cylinder diameter, D) were examined at gap ratios of g/D = 0.1, 0.3, 0.5, 0.7, and 0.9, respectively. Proper Orthogonal Decomposition (POD) analyses were also employed to reveal vortex mechanism in the near wake region. The gap ratio significantly influences the interaction of the vortices. At low gap ratios, the plates directly affect the development of shear layers on both side of the cylinder. The shear layers elongate downstream with a reduction of the vortex shedding frequency. Moreover, Reynolds shear stress, vortex shedding instabilities and vortex street are suppressed in the near wake region with the help of using parallel plates. On the other hand, vortex shedding reinforces instabilities at higher gap ratios. Besides, the most effective gap ratio is different for each the plate lengths to suppress instabilities.

Effects of a detached splitter on the vortex-induced vibration of a 5:1 rectangular cylinder

The present paper examines the vortex-induced vibration (VIV) of a 5:1 rectangular cylinder with a detached splitter in its near wake. The tested gap ratio between the cylinder and the splitter (g/D, where g is the gap between the cylinder rear and the splitter and D is the depth of the rectangular cylinder) ranges from 0.5 to 2.0, with an increment of 0.5. To serve as a reference case, the rectangular cylinder without the splitter is also tested under the same conditions. The test Reynolds number ranges from 32 320 to 56 507. This study delves into the vibration response, pressure distributions, and power spectral densities (PSD) of the cylinder under varying gap ratios. Based on qualitative and quantitative analyses between the cylinder and the splitter using phase average techniques, smoke-wire visualization, and numerical simulation, the different vortex shedding modes according to different gap ratios were identified. Experimental and numerical results show that the detached splitter and its gap ratio play important roles in determining the cylinder VIV properties. For g/D = 0.5, the detached splitter has a sensible mitigation on the cylinder VIV. However, as the gap ratio increases, the VIV response initially recovers to the reference case at g/D = 1.0 and subsequently enlarges at g/D = 1.5 and 2.0. The pressure distribution results showed that the detached splitter demonstrates its effects primarily through fluctuations in the pressure field rather than the mean field. In addition, at g/D = 0.5, a sensibly decayed PSD is observed, while at g/D = 1.0–2.0, an intensified PSD is detected. The underlying mechanism of the detached splitter on the VIV of the 5:1 rectangular cylinder should be attributed to the von Kármán vortex street compared to the reference case.

FLOW STRUCTURES IN THE WAKE REGION OF TWO INCLINED FLAT PLATES IN A SYMMETRICAL TANDEM ARRANGEMENT

Flow properties and wake structures behind bluff bodies have fascinated many researchers for years. Such interest in this phenomenon is due to various applications of bluff bodies in engineering and industry. In this study, flow structures and the downstream wake behind two inclined flat plates in a symmetrical tandem arrangement have been studied experimentally at Reynolds number of 23,000. Constant-temperature hot wire anemometers (CTAs) were employed to quantitatively measure the near wake properties in terms of shedding frequency, velocity components, and turbulent kinetic energy (TKE). The effects of gap ratio (<i>g/D</i>) between the plates and the angle of attack (α) on the wake flow structure have been probed in detail quantitatively. It was found that for a given gap ratio <i>g/D</i>, the Strouhal number decreases as the angle of attack increases. Moreover, for a given angle of attack a, the Strouhal number increases as the gap ratio <i>g/D</i> increases. Interestingly, it was observed that for a given gap ratio <i>g/D</i>, the coherent TKE peak production decreases as the angle of attack increases.

Near-moving-wall flows past three tandem elliptical cylinders at low Reynolds number of 150

Dynamic flows past three tandem elliptic cylinders of equal spacing in parallel arrangement with a moving wall are numerically conducted by the lattice Boltzmann method. The gap ratio (G/D, where G and D are the gap between the wall surface and cylinder center and major axis, respectively) from 0.6 to 2.5 and spacing ratio (L/D, where L is the distance of two adjacent cylinder centers) from 1.5 to 10 are examined at Reynolds number of Re = 150 (based on D). The desired analysis correlates variations of hydrodynamic coefficients, wake structures, and spectral analysis in wide space of G/D and L/D with underlying fluid mechanics. The flow is highly adjustable in G/D−L/D space, dividing into six distinct regimes: overshoot, continuous reattachment, alternative reattachment, wavy, meandering, and coshedding, which are spatially classified into four modes because of flow interference, namely, shear layer, primary, two-layered, and secondary vortex shedding modes. The transition between adjacent modes defines three boundaries. The first boundary always occurs behind the middle or downstream cylinder, whereas the second and third boundaries occur between the upstream and middle cylinders and the downstream cylinder wake. Due to the near-wall flow interference, the hydrodynamic coefficients are highly changeable in L/D−G/D space, signifying the crucially lower drag coefficient of the middle and downstream cylinders than that of a single cylinder. A small G/D determines the increase in lift coefficient of the upstream cylinder as a result of the ground effect, while the shadowing effect of the upstream cylinder induces identical Strouhal numbers of the middle and downstream cylinders.

Mid-Infrared Photons Alleviate Tinnitus by Activating the KCNQ2 Channel in the Auditory Cortex.

Tinnitus is a phantom auditory sensation often accompanied by hearing loss, cognitive impairments, and psychological disturbances in various populations. Dysfunction of KCNQ2 and KCNQ3 channels-voltage-dependent potassium ion channels-in the cochlear nucleus can cause tinnitus. Despite the recognized significance of KCNQ2 and KCNQ3 channels in the auditory cortex, their precise relationship and implications in the pathogenesis of tinnitus remain areas of scientific inquiry. This study aimed to elucidate the pathological roles of KCNQ2 and KCNQ3 channels within the auditory cortex in tinnitus development and examine the therapeutic potential of mid-infrared photons for tinnitus treatment. We utilized a noise-induced tinnitus model combined with immunofluorescence, electrophysiological recording, and molecular dynamic simulation to investigate the morphological and physiological alterations after inducing tinnitus. Moreover, invivo irradiation was administered to verify the treatment effects of infrared photons. Tinnitus was verified by deficits of the gap ratio with similar prepulse inhibition ratio and auditory brainstem response threshold. We observed an important enhancement in neuronal excitability in the auditory cortex using patch-clamp recordings, which correlated with KCNQ2 and KCNQ3 channel dysfunction. After irradiation with infrared photons, excitatory neuron firing was inhibited owing to increased KCNQ2 current resulting from structural alterations in the filter region. Meanwhile, deficits of the acoustic startle response in tinnitus animals were alleviated by infrared photons. Furthermore, infrared photons reversed the abnormal hyperexcitability of excitatory neurons in the tinnitus group. This study provided a novel method for modulating neuron excitability in the auditory cortex using KCNQ2 channels through a nonthermal effect. Infrared photons effectively mitigated tinnitus-related behaviors by suppressing abnormal neural excitability, potentially laying the groundwork for innovative therapeutic approaches for tinnitus treatment.

Technology gap ratio decomposition in smallholder solar saltworks in Indonesia using meta-frontier data envelopment analysis (MetaDEA)

The increasing population in Indonesia results in the rising demand for consumer goods, including salt. Meanwhile, salt production in Indonesia remains traditional, using direct methods by evaporating seawater in open ponds near the coast, producing a final product called “solar salt”. This process depends on sunlight, air, weather, and seasonal climate conditions. This research aims to analyze the technical, technological, and managerial disparities among traditional solar salt farming businesses operated by local communities across regions in Madura Island—the foremost solar salt-producing region in Indonesia. This study employs primary data collected through surveys conducted during the production season in 2023/2024 in three regencies in Madura: Pamekasan, Sampang, and Sumenep. The structured questionnaires captured the input and output data. Meta-frontier Data Envelopment Analysis (meta-DEA) was applied to assess the technical efficiency of conventional solar salt productions across the research regions. The efficiency analysis revealed that, with the current production methods, solar salt farmers achieved an efficiency rate of 46.98%, with an average technical efficiency of 80.83%. This result shows that the decision-making units (DMUs) can enhance their technical efficiency by 19.07%. Meanwhile, the technology gap ratio (TGR) analysis indicates that Sumenep Regency has the highest TGR value, nearing the threshold of 1, suggesting a relatively low technology gap in this regency. The meta-DEA decomposition indicates that the determinant of the average meta-technical inefficiency among solar salt farmers is the technological disparities, with average technological gap inefficiency (TGI) values surpassing managerial gap inefficiency (MGI) values. Conversely, Sumenep Regency has a larger MGI than TGI value, implying that solar salt farmers in Sumenep possess lower managerial decision-making skills than in other regions. The findings suggest the need to enhance the adoption of the latest production technology innovations to address technological gaps in the research locations.

SELF-EMPLOYMENT IN INDIA IN THE FACE OF GROWING POPULATION AND UNEMPLOYMENT: HIGHLIGHTING THE UNDERCURRENT DETERMINANTS AT PLAY

There has been a pressure on consecutive governments and policymakers to create enough jobs in India so that the workforce of India can be used improved and the population can be self-sustainable by becoming economically strong. The creation of jobs, in addition to safeguarding that the working population becomes economically productive, is also a vital avenue for fighting poverty and lack of proper use of intellectual, manual and skill-based potentials of the individuals. India has come to enjoy a distinct advantage in labour market compared to most developed and less developed countries due to the fast changing age distribution of population. India has experienced fairly consistent changes in the first indicator, especially after the 1991 reforms, but the trend in employment has not revealed any consistent or clear pattern. Though the Periodic Labour Force Survey (PLFS) shows increment in worker to population ratio and narrowing of the gender gap in employment in recent past, the unemployment scenario of India still remains disappointing. The present study aims to analyze the factors leading to unemployment and its impact on the Indian economy. The study focusses on how growing population leads to unemployment. The study makes use of secondary data sources and focusses on the present scenario of unemployment in India. The paper analyzes how an increase in population, poverty, illiteracy, inflation and lack of full employment can lead to a slowdown in the growth of the economy.

Effect of adiabatic ground on thermofluidic behavior and cooling time analysis from a hollow tube

Efforts are made to elucidate natural convection around a tube placed on/close to the adiabatic ground in a stagnant ambient air within laminar regime. Thermofluidic characterization is carried out by employing important governing input quantities, such as Rayleigh number gap and aspect ratio The heat loss rate from the inner surface drops abruptly when the tube is placed on the ground. The growth rate of heat loss rate with is relatively more abrupt at higher value of for a constant Nusselt number on outer wall is found to increase monotonically as grows continually for a constant and whereas an opposite trend is anticipated for Nusselt number on inner wall The reduction gradient of with is considerably lower at lower value of in comparison to higher Again, two distinguished zones are identified (Zone A and B), namely, (i) zone A, where the effect of ground on the thermofluidic behvaiour around the tube is observed, and (ii) zone B suggests no effect of ground. Furthermore, cooling time estimation is performed by considering the initial temperature of the cylinder as the wall temperature at time 0 s. The required cooling time reduces considerably with the rise of for a particular and Lastly, a new correlation for Nusselt number has been anticipated. It shows quite satisfactory agreement within ±6% of the computational data.

Assessing the Effectiveness of Climate-Resilient Rice Varieties in Building Adaptive Capacity for Small-Scale Farming Communities in Assam

Rice crop in Assam constitutes a significant portion of the cultivated area, covering around sixty percent of the total area. The state, like many others, confronts the repercussions of climate change, notably evident in recurrent floods that impact agricultural lands. The shifting climate, marked by rising temperatures and increased rainy days, poses threats to crop production. Despite witnessing overall productivity growth, the state grapples with persistent challenges related to flood-induced losses. In response to this, climate-resilient rice varieties were developed to withstand submergence. This study delves into the assessment of the impact of these climate-resilient rice varieties on yield, income, and adoption among farmers. Concentrating on Golaghat and Sivasagar districts, where 106 farmers were interviewed, the research addresses the prevalent challenges in rice cultivation due to changing rainfall patterns. The introduced varieties underwent demonstration in plots, and their effects on yield, income, and adoption were comprehensively evaluated. The study additionally scrutinized the technology and extension gaps in the area, utilizing various indices such as the technology gap, extension gap, technology index, and benefit-cost ratio to measure the efficacy of the introduced varieties. The findings of the study highlight disparities between recommended agricultural practices and the actual methods employed by farmers. Despite these challenges, the introduction of climate-resilient varieties resulted in a noteworthy increase in yield. Economic analysis revealed enhanced profitability from B:C ratio of 0.43 to1.06 and positive changes in economic indicators. The adoption and horizontal spread of these varieties were substantial, with a significant rise from 106 to 378 in the number of adopters and expanded cultivation areas. Overall, the study emphasizes the success of climate-resilient rice varieties in augmenting yield, income, and adoption among farmers. The positive economic changes, coupled with heightened awareness, underscore the importance of promoting such varieties. The study advocates for sustained efforts in disseminating climate-resilient varieties, emphasizing their pivotal role in enhancing farmers' climate resilience. Addressing the identified discrepancies in agricultural practices emerges as a crucial step toward fostering sustainability and optimizing crop yield in the region.

Structure and characteristic analysis of a novel magnetic bearing without thrust disk

Conventional thrust magnetic bearing (TMB) uses large thrust disk to generate axial levitation force. However, due to the existence of thrust disk, it will lead to many problems in assembling and dynamic balance. Moreover, it will even limit rotational speed. In order to solve these shortcomings, a novel TMB with uniform teeth on the stator and rotor is proposed. It replaces the conventional thrust disk with staggered teeth structure between the stator and rotor. This paper obtains analytical expressions of levitation force, current stiffness and displacement stiffness of the novel TMB by equivalent magnetic circuit method and method of air–gap ratio permeance. Considering slot effect between the teeth of stator and rotor, its influence is analyzed by finite-element analysis (FEA) and the expression of displacement stiffness has been modified. The simulation and experiment results show that the proposed TMB can ensure enough bearing capacity by reasonably designing the staggered distance between the teeth of stator and rotor. In addition, under the reasonable tooth structure, TMB can achieve self-recovery ability by utilizing the influence of slot effect on levitation force. Compared with conventional TMB, the proposed TMB has greater advantages in assembly, dynamic balance and high speed. It will be conducive to its application in medical, aerospace and other fields.

Transition to chaos in extended systems and their quantum impurity models

Chaos sets a fundamental limit to quantum-information processing schemes. We study the onset of chaos in spatially extended quantum many-body systems that are relevant to quantum optical devices. We consider an extended version of the Tavis–Cummings model on a finite chain. By studying level-spacing statistics, adjacent gap ratios, and spectral form factors, we observe the transition from integrability to chaos as the hopping between the Tavis–Cummings sites is increased above a finite value. The results are obtained by means of exact numerical diagonalization which becomes notoriously hard for extended lattice geometries. In an attempt to circumvent these difficulties, we identify a minimal single-site quantum impurity model that successfully captures the spectral properties of the lattice model. This approach is intended to be adaptable to other lattice models with large local Hilbert spaces.

Flow topology in the gap and wake of convex curved tandem cylinders

Flow around curved tandem cylinders in the convex configuration has been studied by means of direct numerical simulations, for a Reynolds number of 500 and a nominal gap ratio of 3.0. Spanwise variation of flow regimes, as well as curvature-induced axial velocity, leads to an exceedingly complex vortex dynamics in the wake. Both parallel and oblique vortex shedding are observed. Oblique shedding is connected to repeated occurrences of dislocations. The dislocations are caused by two main mechanisms: frequency differences in the upper part of the curved geometry and shedding of gap vortices into the lower near wake. Both types of dislocations are closely associated with a mode switch in the gap. In parts of the gap, there is low-frequency quasi-periodic asymmetry of the gap vortices, where the flow is biased to one side of the gap for intervals of several wake vortex shedding periods. The switch from side to side is associated with a surge of the vertical velocity, and the frequency of the switch is similar to that of long-term variation of the recirculation length in the lower gap.

Flow-induced vibrations of elastically coupled tandem cylinders

We numerically study the transverse flow-induced vibration (FIV) of elastically coupled tandem cylinders at Reynolds number $100$ , using an in-house immersed boundary method-based solver in two-dimensional coordinates. While several previous studies considered tandem cylinders coupled through flow between them, a hitherto unexplored elastic coupling with fluid flow between them significantly influences FIV. We consider a wide range of gap ratio, reduced velocity, an equal mass ratio of both cylinders and zero damping. A systematic comparison between the classic elastically mounted tandem cylinders and elastically coupled cylinders is presented. The latter configuration exhibits two vibration modes, in-phase and out-of-phase, with corresponding natural frequencies approaching the Strouhal frequency of the system. We quantify variation of the following output variables with reduced velocity and gap ratios: cylinders’ displacement; fluid forces; amplitude spectral density of displacement and force signals; phase characteristics; energy harvesting potential; and discuss the wake characteristics using flow separation, pressure distribution, gap flow quantification, and dynamic mode decomposition characterization. The FIV response is classified into several regimes: initial desynchronization with and without gap vortices; final desynchronization; mixed mode; initial branch; lock-in; upper and lower branch; wake-induced vibration; galloping. We draw upon similarities of computed FIV characteristics with those of an isolated cylinder, in which the lower branch exhibits larger a amplitude than the upper branch. The elastically coupled cylinders show a galloping response similar to an isolated D-section cylinder. By invoking the elastic coupling, we demonstrate FIV suppression and augmentation for in-phase and out-of-phase systems. Our calculations show larger energy harvesting potential at reduced cost for elastically coupled cylinders.

Numerical investigation of specific performance parameters of the S-ROTOR; a Savonius type turbine design

After the energy crisis in the 1970s, studies on alternative electrical energy production processes gained more importance especially considering the possibility of a new energy crisis that may come up nowadays. Despite their low power generation, s-rotor designs used in vertical axis wind turbines are open to development due to their features, such as producing high torque and having many configurations. In this study, the optimum s-rotor design is created using the aspect ratio, overlap ratio, quarter blade gap ratio, and fin as parameters. The effective levels of each parameter were found by performing Computational Fluid Dynamic analysis. Then, using the Responds Surface Optimization method, optimum parameter levels were determined, and the optimum s-rotor design was created. The findings showed that the newly designed s-rotor provided a remarkable performance increase in high tip-speed ratios. In addition, the maximum power coefficient of the s-rotor increased from about 0.06 to 0.10, and it was determined that the aspect ratio was more effective on the power coefficient than the other parameters.

Three-Dimensional Direct Numerical Simulation of Flow past A Near-Wall Circular Cylinder: Combined Effects of Gap Ratio and Boundary Layer Thickness on Flow Profiles and Pressure Distribution

Three-Dimensional Direct Numerical Simulation of Flow past A Near-Wall Circular Cylinder: Combined Effects of Gap Ratio and Boundary Layer Thickness on Flow Profiles and Pressure Distribution

Effect of Clark’s twin block appliance and upper premolar extraction treatment modality on smile aesthetics in skeletal class II malocclusion: a retrospective cross-sectional study

ABSTRACT Introduction Treatment undertaken during growth has various advantages over camouflage treatment including an improved profile and treatment stability. The objective of this study was to compare pre- and post-treatment smile variables in class II malocclusion population treated via functional appliance or upper first premolar extraction. Materials and methods A cross-sectional study was conducted at a tertiary care hospital that included frontal closeup smile (FCS) pictures of 40 patients treated with Clark’s twin block (CTB) appliance and upper premolar extraction (UPE). Smile ratios were calculated, and improvement in smile aesthetics were scored on a visual analogue scale (VAS) by a panel of raters of laypersons, general dentists and orthodontists with 20 subjects in each panel. Friedman and Wilcoxon signed rank tests were used to determine differences between pre-, mid- and post-treatment smile variables. Independent t-test was used to measure differences in improvement of smile aesthetic scores, while simple and multiple linear regression analyses were used to determine any associations between smile aesthetic scores and variables. Results CTB group showed highly statistically significant differences for smile index (SIR), interlabial gap ratio (IGR), visible dentition width ratio (VDWR), archform ratio (AFR), mandibular incisal show ratio (MnIR) and smile arc ratio (SAR). On comparison of post-treatment smile variables between the two treatment groups, statistically significant differences were observed for buccal corridor ratio (BCR) (p = 0.01) and AFR ratios. Conclusions Higher smile improvement scores were seen with CTB treatment with orthodontists rating it higher than UPE. Improvement in maxillary incisal ratio causes an increase in smile aesthetic scores.

Hydrodynamic forces in array of uniform and non-uniform cantilever beams

In this paper, we have implemented the three-dimensional Boundary Element Method (BEM) to solve the hydrodynamic forces in arrays of two, three, and five thin beams oscillating with small amplitudes in a fluid. We solve the unsteady Stokes equation by considering the oscillatory Stokeslet. The non-dimensional hydrodynamic function is validated through numerical solutions obtained using the Finite Element Method (FEM) at various frequency parameters and gap ratios. We analyse the influence of the relative phase and amplitude ratio of a uniform beam and a non-uniform two-beam array in terms of added mass and damping coefficients. Additionally, we compare the solution with experimental results available in the literature as a function of gap ratio. The analysis presented in this paper can be useful for optimizing arrays used in Atomic Force Microscope (AFM), biosensors, and energy harvesters.

Urbanization and urban energy eco-efficiency: A meta-frontier super EBM analysis based on 271 cities of China

This study quantifies urban energy eco-efficiency (UEEE), examines the technological gap ratio (TGR) in regional energy use, and analyzes the impact of China's urbanization on UEEE. We propose a hybrid model that combines the Meta-frontier Super Epsilon-based Measure (Super-EBM) model and a Tobit model, using data from 271 Chinese cities between 2003 and 2020. The results indicate that the overall UEEE is ecologically inefficient throughout the study period. TGR has a positive impact on UEEE, with notable regional differences. However, the marginal effect of TGR on UEEE in the east region is lower than that in the other three regions. In addition, the urban population growth and UEEE exhibit a U-shaped relationship in the east and central regions, while an inverted U-shaped relationship is observed in the west region. The relationship between urban economic growth and UEEE is positive, accompanied with diminishing marginal effects in the central and west regions, whereas fixed asset investment negatively affects UEEE in the four regions, showing different marginal effects. These findings highlight the importance of considering technology and local urbanization in policy making.

A General Case of a Line Contact Lubricated by a Non-Newtonian Giesekus Fluid

A steady plane hydrodynamic problem of lubrication of a lightly loaded contact of two parallel cylinders lubricated by a non-Newtonian fluid with Giesekus rheology is considered. The advantage of this non-Newtonian rheology is its ability to properly describe the real behavior of formulated lubricants at high and low shear stresses. The problem is solved by using a modification of the regular perturbation method with respect to the small parameter α, characterizing the degree to which the polymeric molecules of the additive to the lubricant follow the streamlines of the lubricant flow. It is assumed that the lubricant relaxation time and the value of α are of the order of the magnitude of the ratio of the characteristic gap between the contact surfaces and the contact length. The obtained analytical solution of the problem is analyzed numerically for the dependencies of the problem characteristics such as contact pressure, fluid flux, lubrication film thickness, friction force, energy loss in the lubricated contact, etc., on the problem input parameters.