Relative Curves Research Articles

Re-examining the Kuznets Curve Hypothesis for South Asian Countries: New Evidences

This study re-examines the validity of Kuznets curve hypothesis for six South Asian countries, namely, Pakistan, Nepal, Bhutan, Sri Lanka, India, and Bangladesh, over the period 1991–2018. The Pooled Mean Group (PMG) technique results in the short and long run reveal an S-shaped curve relationship between income inequality and Gross Domestic Product (GDP) per capita for all countries, that is, negative at the beginning, positive after the first turning point (GDP per capita level, US$473), and negative after the second turning point (GDP per capita level, US$3827) when GDP per capita reaches the maximum level. In contrast, the country-specific results show, that the first and second turning points of GDP per capita are US$468 and US$2298 for India, US$445 and US$1408 for Pakistan, US$450 and US$9045 for Bhutan, and US$925 and US$6836 for Sri Lanka, which support the validity of the S-shaped curve. Moreover, the results also show the existence of N-shaped curve with GDP per capita (i.e. first and second) turning points of US$473 and US$2864 for Bangladesh and US$105 and US$3568 for Nepal. The findings suggest that income inequality gaps in Asian countries seem to be conditional on the levels of GDP per capita. In this regard, expansionary fiscal policy, specifically in the form of government spending, promotion of exports and employment, and price stability can play a vital role in increasing the GDP per capita levels and narrowing the income inequlaity gaps in the selected Asian countries.

The Impact of Public Transportation on Carbon Emissions—From the Perspective of Energy Consumption

Background: Transportation has become the second-largest source of global carbon emissions. Promoting low-carbon development by means of public transport and green travel and analyzing the mechanism and path of the carbon emissions reduction effect of public transport have become key to reducing carbon emissions in the transportation field and achieving “carbon peak and carbon neutrality”. Methods: The data from 30 provinces (2010–2019) were extracted from China Emission Accounts and Datasets (CEADs), China Energy Statistical Yearbook, China Statistical Yearbook, and China Automobile Statistical Yearbook. The two-way fixed-effect model was used to explore the carbon emissions reduction effect of public transport development level. The mediating-effect model was used to verify the transmission role of energy consumption in the carbon emissions reduction effect of public transport development level. Results: The study suggests that the public transport development level and CO2 emissions are negatively correlated, showing an “Inverted U-shaped” curve relationship. Energy consumption is the transmission path of the carbon emissions reduction effect of public transport development level. The public transport development level adjusts the energy consumption structure through the traffic substitution effect, energy input optimization effect, and industrial structure optimization effect and then acts on carbon emissions. Moreover, the contribution rate of energy consumption is about 4.22%. In addition, regional heterogeneity is present in the transmission path of the carbon emissions reduction effect of public transport development level based on energy consumption. The carbon emissions reduction effect of public transport development level is more significant in the central and western regions than the eastern and northeast regions of China. Conclusion: The transmission mechanism of energy consumption in the carbon emissions reduction effect of public transport is worthy of attention. To promote low-carbon and circular development in the transportation sector, it is urgent to accelerate the green upgrading of transportation infrastructure, promote the low-carbon transformation of energy production and consumption, promote carbon emissions reduction in public transport, and strengthen the linkage regulation between effective government and an effective market.

Association between sleep duration and incidence of type 2 diabetes in China: the REACTION study.

Backgrounds:Inadequate sleep duration is associated with a higher risk of type 2 diabetes and the relationship is nonlinear. We aim to assess the curve relationship between night sleep duration and the incidence of type 2 diabetes in China.Methods:A cohort of 11,539 participants from the REACTION study without diabetes at baseline (2011) were followed until 2014 for the development of type 2 diabetes. The average number of hours of sleep per night was grouped. Incidence rates and odds ratios (ORs) were calculated for the development of diabetes in each sleep duration category.Results:Compared to people who sleep for 7 to 8 h/night, people with longer sleep duration (≥9 h/night) had a greater risk of type 2 diabetes (OR: 1.27; 95% CI: 1.01–1.61), while shorter sleep (<6 h/night) had no significant difference in risk of type 2 diabetes. When the dataset was stratified based on selected covariates, the association between type 2 diabetes and long sleep duration became more evident among individuals <65 years of age, male, body mass index <24 kg/m2 or with hypertension or hyperlipidemia, no interaction effects were observed. Furthermore, compared to people persistently sleeping 7 to 9 h/night, those who persistently slept ≥9 h/night had a higher risk of type 2 diabetes. The optimal sleep duration was 6.3 to 7.5 h/night.Conclusions:Short or long sleep duration was associated with a higher risk of type 2 diabetes. Persistently long sleep duration increased the risk.

Modeling analysis of coalbed methane co-production interference: A case study in Eastern Yunnan Basin, China

The interlayer interference in coalbed methane (CBM) co-production wells restricts the effective development of CBM resources in multi-seam areas; however, the establishment of quantitative interference indicators still remains difficult to date resulting from the complex geological formation evolution and reservoir development techniques. In this paper, the reverse flow rate and the water production inhibition index of the coal seam were derived from the transient inflow performance relationship (IPR) curve to characterize the interlayer interference. The IPR curves of different reservoir and aquifer parameters were calculated on the modified reservoir model using a CBM well as a case in East Yunnan Basin. From the data processing for obtaining interlayer interference indicators, the pressure difference between coal reservoirs was found to be the most critical factor in generating reverse fluids, with a 15% difference and the interference amounting to 244.08 m3 d·KPa−1, followed by coal seam thickness and permeability (∼18.00–25.00 m3 d·KPa−1). Gas content, Langmuir pressure, and Langmuir volume contribute slightly to the interlayer interference. Second, any increase in thickness or permeability of the aquifer will significantly increase the water production rate of the coal seam due to water influx. Significantly, the reverse flow rate will be increased when the aquifer is located in a higher fluid pressure system. Instead, the reverse flow rate will be decreased in the case of a lower pressure system. Finally, continuous pressure drops lead to the coal seam and aquifer recharge capacity higher than the set drainage system, resulting in the coal seam water not being removed effectively. The coal seam's water production inhibition index shows a positive correlation with the thickness and permeability of the aquifer and a negative correlation with the drainage intensity. The results of this paper bridge the gap between the identification interference indicators and the possible combination of production layers, and it also provides new insights for enhancing CBM development in the East Yunnan Basin.

The dynamics of income inequality in Africa: An empirical investigation on the role of macroeconomic and institutional forces

Reducing income inequality is a crucial goal of sustainable development as income inequality often viewed as harmful to economic growth. The main aim of this paper was to empirically assess the macroeconomic and institutional drivers of income inequality in Africa. We use a Kuznets curve framework, which emphasises the role of income per capita in explaining the time path of inequality. In contrast to much of the literature, we explicitly examine the possibility of the existence of multiple income steady states. Using the concept of clubs of convergence, we show that per capita income is divergent and identify four steady states to which groups of economies converge (i.e., high-income to low-income economies). Using panel data models and a data set encompassing 52 African countries spanning the years 1980–2017, we show that once these multiple steady states are accounted for, the Kuznets curve relationship becomes unstable. Our findings suggest that inequality may be increasing in high-income countries in Africa, while decreasing in low-income or the least developed economies. In addition, the role of macroeconomic and institutional factors in explaining income inequality is limited and differ across convergence clubs. Evidence suggests the importance of fiscal, employment and monetary policies and the rule of law to tackle inequality in high-income economies, while they have no statistically significant role in low-income economies’ income inequality.

Importance of Weighting High-Resolution Proxy Data From Bivalve Shells to Avoid Bias Caused by Sample Spot Geometry and Variability in Seasonal Growth Rate

Shells of bivalve mollusks serve as archives for past climates and ecosystems, and human-environmental interactions as well as life history traits and physiology of the animals. Amongst other proxies, data can be recorded in the shells in the form of element chemical properties. As demonstrated here with measured chemical data (10 elements) from 12 Arctica islandica specimens complemented by numerical simulations, mistakes during sclerochronological data processing can introduce significant bias, adding a further source of error to paleoenvironmental or biological reconstructions. Specifically, signal extraction from noisy LA-ICP-MS (Laser Ablation—Inductively Coupled Plasma—Mass Spectrometry) data generated in line scan mode with circular LA spots requires a weighted rather than an arithmetic moving average. Otherwise, results can be in error by more than 41%. Furthermore, if variations of seasonal shell growth rate remain unconsidered, arithmetic annual averages of intra-annual data will be biased toward the fast-growing season of the year. Actual chemical data differed by between 3.7 and 33.7% from weighted averages. Numerical simulations not only corroborated these findings, but indicated that arithmetic annual means can overestimate or underestimate the actual environmental variable by nearly 40% relative to its seasonal range. The magnitude and direction of the error depends on the timing and rate of both seasonal shell growth and environmental change. With appropriate spatial sampling resolution, weighting can reduce this bias to almost zero. On average, the error reduction attains 80% at a sample depth of 10, 92% when 20 samples were analyzed and nearly 100% when 100 samples were taken from an annual increment. Under some exceptional, though unrealistic circumstances, arithmetic means can be superior to weighted means. To identify the presence of such cases, a numerical simulation is advised based on the shape, amplitude and phase relationships of both curves, i.e., seasonal shell growth and the environmental quantity. To assess the error of the offset induced by arithmetic averaging, Monte Carlo simulations should be employed and seasonal shell growth curves randomly generated based on observed variations.

Analysis of Buckling Deformation for the Side Plate of Rectangular CSFT Column Based on Plate Theory with Bi-Axial Loads

In this paper, under the condition of bidirectional stress, the buckling deformation of the side plate in a rectangular concrete-filled steel tube (CFST) column has been studied in detail. We have conducted a theocratical analysis, an experimental validation and a finite element simulation to investigate the influences of the height-width ratios and Nominal Poisson’s ratios on the buckling form of the side plate, and we also try to explain the change of buckling form between unidirectional and bidirectional stress, both of them can provide a good reference and basis for design and application of the CFST column. The specific work can be summarized as follows: Firstly, a theoretical analysis has been conducted to study the buckling coefficient solution method of the thin plate under the conditions of axial compress and transverse tension. Then, under the conditions of the unidirectional and the bidirectional stress, a comparative study is carried out to investigate the changing relationship of the buckling coefficient (k) of the side plate; the results indicate that the buckling characteristic is changed due to the bidirectional stress, meanwhile, the buckling coefficient and the number of buckling half-wave will increase. Furthermore, the existing outcomes and the numerical simulations are adopted to study the relevance between the number of the elastic buckling half-wave in the side plate and the corresponding height-width ratio of the component; the results indicate that the former is larger than the latter. Finally, based on the obtained, the buckling relationship curve, the conclusion can be drawn as follows: when the bidirectional stress has been applied to the side plate, there is an equal interval between the different buckling half-waves; meanwhile, the interval shows a quadratic function reduce trend with the increase of nominal Poisson’s ratio.

A trinity fingerprint evaluation system of traditional Chinese medicine

This study focused on developing a set of quality evaluation methods that can reflect the multi-levels and multi-characteristics of traditional Chinese medicine (TCM). Taking licorice (Glycyrrhiza glabra L.) as the method development sample, the feasibility of multi-markers assay by monolinear method (MAML) was explored through the standard curve relationship among active components for the first time. Using glycyrrhizic acid as measurement marker, MAML can simultaneously quantify five components of licorice, including isoliquiritigenin, isoliquiritin apioside, liquiritigenin, liquiritin and liquiritin apioside. Comparing MAML and quantitative analysis of multi-components by single-marker (QAMS) to the external standard method (ESM) respectively, it was found that there was no significant difference in the content of components that were calculated by MAML and ESM (the relative error (RE) was generally less than 2.00%). However, the RE of the component content calculated by QAMS fluctuated greatly, indicating that the MAML was more accurate than QAMS. In addition, UV and THz quantum fingerprints were initiated by the interval erasure method. Taking the systematically quantified fingerprint method as the core, a "Trinity" fingerprint quality evaluation system based on HPLC, UV and THz was developed. The system successfully distinguished the quality differences of licorice samples from 13 producing areas and two ecological models by the comprehensive evaluation results. Simultaneously, the quality information of licorice at different technical levels was revealed. Finally, bivariate correlation analysis was used to examine the linkage between UV/HPLC and antioxidant spectrum efficacy, and the two-dimensional activity spectrum of licorice was provided. It may furnish a more thorough and objective analytical technique for licorice and even other TCMs in chemical fingerprint features, chemical bond vibration characteristics and biological activity information.

Modelling informetric data using quantile functions

• New properties of Leimkuhler curve using quantile functions. • Several quantile function models for bibliometric data analysis. • Relationship of Leimkuhler curve with L-moments, Gini index, reliability measures and economic measures. • Analysis of SJR scores and H-index using quantile functions. In the present work, we propose some transformations of quantile functions in informetry. We derive some new properties of Leimkuhler curves using quantile functions. Several quantile function models are presented along with the measures useful in informetrics. Applications of quantile functions in modelling and analysis of bibliometric data are also discussed with the aid of real data sets.

Finite-Element Analysis of Vertical Displacement of Laminated Rubber Bearing under Earthquake Action for Disaster Resilience of the Smart City

With the construction and development of smart cities, higher requirements have been put forward for the prediction and control of major natural disasters. For the prevention of earthquake disasters in super high-rise buildings, the rubber bearings of high-rise seismic isolation structures may have the risk of tensile damage in high-intensity areas, which has always been an urgent problem to be solved. In this paper, a unidirectional horizontal compression-shear experiment with 400% large deformation was conducted on the laminated rubber bearing (LNR500), and the relationship curve of vertical displacement with horizontal displacement of the bearing was obtained. According to the experimental data, an ideal elastic-plastic principal structure model was selected for the steel and a Yeoh principal structure model was selected for the rubber material, and the finite element analysis was carried out for the bearing. The time course curves of displacement, velocity and acceleration of the vertical and horizontal deformation of the laminated rubber bearing under the earthquake were obtained.

Productivity Prediction of Fractured-Vuggy Reservoirs under Time-Varied Flow Rates and Bottom Hole Flow Pressures

Fracture-vuggy oil reservoirs contain micrometer-sized dissolved secondary pores, fractures, and meter-sized karst caves. Generally, the researches on the flow mechanism of fractured-vuggy reservoirs are based on the assumption of karst cave-fracture-matrix triple medium that gives a partial differential equation which the pressure satisfies. This triple medium flow equation lays the basics for the well testing theory of fractured-vuggy reservoirs. However, the triple medium equation cannot reflect the actual existence of the karst cave volume in geology. Recently, we proposed a theory of fracture-cave seepage flow coupled with vug pressure wave which takes the vug size into consideration and thus can better describe the fracture-vuggy reservoirs. On the basis of this theory, this work combines the change of formation pressure with time, Duhamel’s theorem, and well testing theory to obtain the mathematical expression of time-varied bottom hole pressure and flow rate in Laplace space. Then, the dynamic inflow performance relationship (IPR) curve of fractured-vuggy reservoir is obtained by inverse Laplace transformations. This dynamic IPR curve can predict the productivity for fractured-vuggy reservoirs using parameters from well test interpretations of pressure recovery. The correctness of this productivity prediction method is verified by filed fractured-vuggy oil well. This productivity prediction method not only utilizes and expands the application of well test interpretation data but also shortens the test time and reduces test costs, which is important for oil development.

The Effects of Salt-Lake Salt Solution on the Strength of Expansive Soil

Expansive soils are widely distributed and often cause serious damage to structures. Hanzhong expansive soil and Yulin salt-lake solution were adopted to investigate the effect of salt-lake salt solution on the strength of expansive soil. Expansive soils modified with salt-lake salt solutions with different concentrations (0.1, 0.5, and 1.0 mol/L) were evaluated by X-ray diffraction (XRD), Atterberg limit, free swelling, no load swelling ratio, and triaxial compression tests. The improved expansive soil research using salt-lake salt solution was carried out based on the macroscopic mechanical characteristics. Test results showed that the addition of salt-lake solution effectively inhibited the expansibility of soil. With the increase of the concentration of salt-lake solution, liquid limit, plastic limit, plastic index, free expansion rate, no load swelling, cohesion, and internal friction angle of expansive soil were decreased in varying degrees, and stress-strain relationship curve gradually showed strain softening trend. The reason for the above results was believed to be that salt-lake salt solution reduced the force between particles on shear surface and reduced mutual hindrance.

A new method for evaluating the pore structure complexity of digital rocks based on the relative value of fractal dimension

Natural porous media have extremely complex pore structures, which greatly affect the material properties. However, it remains a challenge to characterize the pore structure complexity accurately. Fractal geometry is one of the effective tools for this task, which allows for quantitative analysis. In this paper, a new method is proposed for evaluating the pore structure complexity of digital rock models by using the relative value of box-counting fractal dimension. The proposed method transforms the judgment criterion from the comparison of the absolute value to the comparison of the relative value in the fractal dimension by establishing an intermediate fractal reference model. Firstly, the digital core model with progressively changing porosity and pore structure is reconstructed using a numerical modeling means, and three kinds of fractal dimensions of the model are estimated by the box-counting algorithm. Meanwhile, the relationship curve between fractal dimension and porosity is employed as the fractal reference model. Then, the fractal dimensions of the study samples and the reference model are mapped to the same coordinate system. By comparing their relative positional relationship, the pore structure complexity of samples is effectively evaluated and classified. Finally, CT samples are taken as a concrete example to illustrate the application of the proposed method. The correctness and availability of this method are verified through the comprehensive analysis of digital images, pore structure, porosity, and permeability. The constructed method provides a reference for a more accurate evaluation and classification of the complexity of pore space in digital rock physics.

An Exponential Curve Relationship Between Serum Urate and Migraine: A Cross-Section Study From NHANES.

BackgroundMigraine is a common neurological disease and an important cause of disability worldwide. Serum urate is the end product of purine metabolism in Homo sapiens and other hominoids. Previous studies about the serum urate level in migraine were contradictory. Hence, we present a cross-section study to clarify the association between serum urate and migraine and explore the dose effect of serum urate on migraine.Materials and MethodsThe data for this cross-section study were acquired from the National Health and Nutrition Examination Survey (NHANES). A diagnosis of migraine was made through patient the self-reported and prescription medication. For data analysis, the weighted linear regression model, weighted chi-square test, logistic regression models, smooth curve fittings, and the two-piecewise linear regression model were utilized for data analysis. All data analysis was conducted on Empower software.ResultsTotally, 18,637 participants were enrolled in this study, of which 208 were migraineurs. The rest were set as control. There existed a statistically significant difference in mean age (p = 0.0389), gender (p< 0.0001), race (p< 0.0001), data release cycle (p = 0.048), drug usage, blood albumin (p< 0.0001), blood total protein (p< 0.0001), hemoglobin (p< 0.0001), serum iron (p< 0.0001), and serum urate (p< 0.0001) between the two groups. According to logistic regression models, there existed no consistent linear relationship between serum urate and migraine before (model 1: odd ratio (OR) = 0.83, p = 0.0004) or after adjusting for confounders (model 2: OR = 0.96, p = 0.5198; model 3: OR = 0.84, p = 0.0184). However, smooth curve fittings found an exponential curve relationship between serum urate and migraine. Furthermore, when serum urate was more than 7.8 mg/dl, higher serum urate was correlated with higher migraine occurrence (model 1: OR = 1.54, p = 0.0022; model 2: OR = 1.51, p = 0.0050; model 3: OR = 1.77, p = 0.0348). Besides, 8 out of the 208 migraineurs had a serum urate higher than 7.8 mg/dl.ConclusionsIn conclusion, there existed an exponential curve relationship between serum urate and migraine, with an infliction point of 7.8 mg/dl. When serum urate was more than 7.8 mg/dl, increased serum urate was correlated with higher migraine occurrence.

Development of Stainless Steel Yarn with Embedded Surface Mounted Light Emitting Diodes.

The integration of electronic components in/onto conductive textile yarns without compromising textile qualities such as flexibility, conformability, heat and moisture transfer, and wash resistance is essential to ensuring acceptance of electronic textiles. One solution is creating flexible and stretchable conductive yarns that contain tiny surface-mounted electronic elements embedded at the fiber level. The purpose of this work was to manufacture and subsequently evaluate the physical features and electromechanical properties of stainless steel yarn with light-emitting surface mounted devices (SMDs) embedded in it. The SMDs were successfully integrated into a conductive stainless steel yarn (SS) by inserting crimp beads and creating a bond through hot air soldering machines, resulting in what we call an E-yarn. The relationship curves between gauge length and electrical resistance, and the relationship curves between conductive yarn elongation and electrical resistance, were explored experimentally. The results of the analysis demonstrated that E-yarn had a lower tensile strength than the original electrically-conductive SS yarn. The effects of the washing cycle on the conductivity of the E-yarn were also investigated and studied. The results showed that E-yarns encapsulated at the solder pad by heat shrink tube still functioned well after ten machine wash cycles, after which they degraded greatly.

Coordinated slag Disposal From Horizontal Boreholes During Hydraulic Cutting Based on Two-Phase Flow Theory

The purpose of the study is to explore the mechanism of coordinated slag disposal in the hydraulic cutting process, ensure the safety implementation of the hydraulic cutting operation and increase the success rate of hydraulic cutting. In the ultra-high pressure hydraulic cutting technique, the method for determining the cutting pressure is ambiguous, the coordination mechanism of various factors (including cutting pressure and coal-dropping speed) lingers unclarified; the slag disposal mechanism during hydraulic cutting is inexplicit. Aiming at these problems, a model for coordinated slag disposal during hydraulic cutting based on coal‐water two-phase flow was established. The critical flow velocity in the moving laminar flow regime is taken as that during the coordinated slag disposal from boreholes. The relationship curve between the coal-dropping speed and cutting pressure under different Protodyakonov coefficients of coal seams was obtained. Hence, the model for coordinated slag disposal during hydraulic cutting was established; the selection interval of reasonable pressure for coordinated slag disposal during hydraulic cutting was determined. The reasonable cutting pressure for slag disposal in coal seams with a Protodyakonov coefficient of 0.48 was determined as about 80 MPa. During the cutting test, the average net gas extraction from the boreholes for hydraulic cutting was 4.5 times larger than that from the conventional boreholes. Furthermore, the gas permeability coefficient of the boreholes for hydraulic cutting increased by 25 times; the effective extraction radius was more than doubled. It indicated that the model for reasonably selecting the cutting pressure based on the coordinated slag disposal theory can effectively guide the selection of the cutting pressure on site. While solving various problems occurring in the hydraulic cutting process on site, the model can be used to improve the cutting effect, which provides a theoretical basis for reasonably selecting the pressure during ultra-high pressure hydraulic cutting.

A Spatial Empirical Examination of the Relationship Between Agglomeration and Green Total-Factor Productivity in the Context of the Carbon Emission Peak

We aim to explore the impact of economic agglomeration on the development of green total-factor productivity (GTFP) from both theoretical and empirical levels. We use the non-radial directional distance function method to formulate the GTFP index and further empirically study the impact of economic agglomeration on GTFP. The results indicate that: 1) there is a “U-shaped” curve relationship between economic agglomeration and GTFP, and the formation mechanism is that the economic agglomeration has a threshold effect on the agglomeration externalities such as infrastructure sharing, knowledge spillover, and labor market upgrading. 2) The mismatch of industrial structure is an important reason that the economic agglomeration in this region has not produced an obvious spatial spillover effect on other regions; relaxing restrictions on the concentration of economic activity to regional centers would contribute to the improvement of GTFP. 3) GTFP has the classic “snowball effect” in the time dimension but has the obvious “warning effect” in the space and time dimension. The conclusions of the research show that it is necessary to conform to the redistribution of economic geography, promote the rational allocation of human resources in the territorial space, and promote the coordination of economic agglomeration and green economic development goals.

Research on Kuznets Curve in Hubei and Gansu Provinces

Due to the differences in geographical location, industrial structure and economic development in China, the level of economic development and pollution emission levels in different regions vary widely. Using the environmental Kuznets curve theory, this paper conducts an empirical study with Hubei and Gansu provinces as examples, and analyzes the relationship between wastewater, carbon dioxide and sulfur dioxide emissions and per capita GDP in the two provinces during 2005-2015. The research shows that the total amount of carbon dioxide emissions and per capita GDP in Hubei presents a classic Kuznets curve "n" curve, while the three indicators in Gansu cannot form a reasonable Kuznets curve relationship with per capita GDP. Combining the two provinces According to the specific conditions of different industrial development stages, relevant policy suggestions are put forward to promote energy conservation and emission reduction in the two provinces while promoting economic development, so as to achieve a reasonable development trend of the Kuznets curve and usher in a decline in pollutant emissions.

Analysis of the Influence of the Channel Layout and Size on the Hydraulic Performance of Emitters

In this paper, a split-flow channel layout with one (group) inlet and two (group) outlets is adopted, based on computational fluid dynamics technology, and compared with the current commonly used channel with one (group) inlet and one (group) outlet emitter. On the premise of the same outlet spacing, the pressure–flow relationship curve and slope of the split-flow emitter were analyzed under the three channel layouts of non-return, single-sided re-entry, and bilateral re-entry, with different channel widths and lengths. When exploring the influence of the channel layout and size on the hydraulic performance of split-flow emitters, the results showed that when the split-flow emitter with a non-return channel is adopted and the hydraulic performance is not reduced, the single-side channel length is half that of the one-in-one-out emitter, meaning the channel width needs to be reduced by 15%. When the channel layout is a single-sided channel re-entry, the hydraulic performance is better than that of the one-in-one-out emitter; if the hydraulic performance of the two remains unchanged, the channel width can be increased by 10% or the single-sided channel length can be reduced by 20%. When the channel layout is a bilateral channel re-entry, the channel width can be increased by nearly 30% if the hydraulic performance of the 2 is consistent, and the single-side channel length is increased by about 50%. When the split-flow emitter adopts a non-return channel layout, the channel width needs to be reduced to ensure the hydraulic performance is consistent. If the layout of single-sided channel re-entry or bilateral channel re-entry is adopted, the hydraulic performance is better than that of the one-in-one-out emitter and the hydraulic performance of the two is consistent. Thus, the channel length can be reduced or the channel width increased, which is beneficial for improving the anti-clogging performance of the emitter.

Industrial co-agglomeration, green technological innovation, and total factor energy efficiency.

The double-wheel driven of manufacturing and producer services industrial co-agglomeration is of great significance for transforming the economic growth mode driven by a single industry, integrating and extending regional resources, and improving energy efficiency. Based on panel data from 2004 to 2019, this paper uses the spatial Dubin model to analyze the impact of industrial co-agglomeration on total factor energy efficiency (TFEE) and its regional heterogeneity. Moreover, the mediating model is employed to examine the mediating effect of green technological innovation in the industrial co-agglomeration affects TFEE. Last but not least, the threshold panel regression model is conducted to verify the nonlinear relationship between industrial co-agglomeration and TFEE. The results show that there is a U-shaped curve relationship between industrial co-agglomeration and TFEE. Moreover, there are obvious regional heterogeneities in the impact of industrial co-agglomeration on TFEE and its spatial spillover effect. Meanwhile, industrial co-agglomeration has a significant indirect impact on TFEE through green technological innovation. In addition, there is a single threshold effect on the impact of industrial co-agglomeration on TFEE, only when the industrial co-agglomeration degree crosses the threshold value of 0.6329, can it positively promote the improvement of TFEE.