Resistance Reduction Effect Research Articles

Comparative Effect of Insulin Resistance Reduction and Hormonal Alterations on Type 2 Diabetes Remission After Bariatric Surgery.

Background: Bariatric surgery is known to induce weight loss and diabetes remission in patients with type 2 diabetes (T2D), but the exact mechanism of glycemic normalization needs to be defined. Methods: The study included patients with BMI ≥ 35 kg/m2, obesity history ≥ 10 years, and planned bariatric surgery. At baseline and 3 and 6 months after surgery, all patients underwent anthropometric measurements, body composition and blood tests (including insulin, glucagon, and incretins during oral glucose tolerance test (OGTT)), and hyperinsulinemic euglycemic clamp tests. Diabetes remission was defined if the person reached HbA1c < 6.5% after surgery and glucose-lowering therapy withdrawal. Results: The study included 86 patients, divided into groups with no diabetes (control group, n = 44) and T2D (n = 42). Most patients with T2D reached normoglycemia at 6 months. BMI and insulin resistance (according to M-index) decreased in T2D group comparably to people without diabetes. At 6 months, people with T2D at baseline had less insulin and GLP-1 secretion and higher glucagon level during OGTT when compared to the control group. Conclusions: We conclude that weight and insulin resistance reduction is sufficient for T2D remission. The absence of insulin, glucagon, and incretin restoration is not crucial for the glucose metabolism in the short-term, but it may explain the relapse of T2D years after bariatric surgery.

Effect of dynamic resistance reduction in spiral copper-plated multifilament coated conductors

Abstract Theoretically, it has been shown that the dynamic resistances of coated conductors can be reduced by decreasing their effective width through multifilamentation. In the case of copper-plated multifilament coated conductors, coupling currents are expected to worsen the effect of multifilamentation in reducing dynamic resistance. Therefore, the purpose of this study is to experimentally investigate the dynamic resistances of spiral copper-plated multifilament coated conductors, which are expected to reduce the coupling time constant in a manner similar to twisted low-Tc superconducting wires. We measured the dynamic resistance of four different samples—straight monofilament, straight multifilament, spiral monofilament, and spiral multifilament coated conductors—using the four-terminal method. We discuss the dynamic resistivity characteristics of the copper-plated multifilament coated conductors by comparing the magnetic field dependence of the dynamic resistivity, normalized by the critical current of each sample.&amp;#xD;

A turbulent flow topology optimization method for diverging tee resistance reduction

The resistance of local components in piping and duct systems significantly affects the energy consumption of fans and pumps, accounting for 40–60 % of the total building energy consumption. In this paper, an improved topology optimization method for variable density turbulent flow is proposed to design a low-resistance diverging tee structure in piping and duct systems. The advantages of the improved optimization method over the traditional method are analyzed using finite element numerical simulation, and the applicability of the proposed method is verified in the Reynolds number range of 0.6 × 105–2.6 × 105. In order to ensure the resistance reduction effect of the topology diverging tee under multiple operating conditions, the local resistance coefficients under nine flow ratios were simulated and calculated using the finite volume method. The results show that the topology diverging tee can significantly reduce the resistance. Compared with the traditional tee, the maximum resistance reduction rates in the straight-through direction and branch direction reached 63 % and 59 %, respectively. In addition, the intensity of secondary flow in five downstream sections was analyzed based on the dimensionless parameter Se. Finally, the actual resistance reduction effect of the topology diverging tee was experimentally verified. The optimization method and analysis results proposed in this study can provide a reference for the optimal design of pipelines with low resistance in energy-saving operation of buildings and in engineering fields such as petroleum and chemical industries.

Insights of particle types on interface wear properties of different water-lubricated bearing materials

The particle types in lubricating medium are very important to the performance of friction interface. Three potential ship water-lubricated bearing materials (PBT, PEEK and Polyurethane composite 10. wt% carnauba wax (PUCW10)) were selected to carry out tribological tests in water environment with different particles (Al2O3, SiO2, sand or clays). The results show that all three materials showed significant friction coefficients and wear in water environment containing sand below 60 µm at 0.5 MPa and 150 r/min. and the surface hardness, hydrophilicity and particles characteristics affect the wear properties of samples. PUCW10 benefits from the wax layer formed by carnauba wax component on worn surface to avoid excessive wear, thereby obtaining better particle wear resistance and vibration reduction effect.

Effect of ultrasonic on thermo-hydraulic characteristics of shell and tube heat exchangers with twisted tape

Ultrasonic technology was combined with twisted tape insert technology to improve the performance of shell and tube heat exchangers. The effects of sound intensity, sound frequency, and ultrasonic transducer position on thermal transfer, resistance reduction, and overall performance of shell and tube heat exchangers with twisted tape (STHXTT) at different Reynolds numbers were investigated compared to the non-ultrasonic conditions. The experimental results show that applying ultrasonic can significantly enhance thermal transfer, reduce flow resistance, and improve the overall performance. The maximum increase of Nu is 36.53 %, the maximum decrease of f is 12.50 %, and the maximum value of PEC is 1.41. With the increase in Reynolds number, the performance is enhanced but the resistance reduction and overall performance are weak. When the ultrasonic intensity increases, the thermal transfer and resistance reduction performance is enhanced, but a critical ultrasonic intensity exists. When the ultrasonic intensity is large enough, the ability to reduce resistance is enhanced with the decrease of ultrasonic frequency. When the ultrasonic transducer is installed vertically, the thermal transfer performance is the best, however, the resistance reduction effect is the worst. When installed horizontally, the STHXTT has the best resistance reduction performance but the worst thermal transfer effect.

Resistance reduction characteristics analysis of the tee based on field synergy and viscous dissipation

There has been increasing attention on reducing pipe resistance friction losses, particularly those represented by tees, in heating, ventilation, and air conditioning systems to enhance the sustainability of buildings. This paper analyzes the resistance characteristics, flow patterns, and force conditions of tee, identifies the locations with great resistance losses, and proposes a novel tee with an added the U-shaped deflector. The resistance reduction effect of the U-shaped deflector through field synergy and viscous dissipation is also analyzed. The results indicate that the resistance loss of the tee is mainly from the main-branch pipe section, with the maximum velocity gradient on the outer side of the branch and the inner side of the straight pipe. The fluid resistance friction loss in the section taken by the branch pipe is much greater than that in the main pipe section, the fluid resistance friction loss in the section taken by the main pipe is not affected by the pipe diameter ratio, and the internal friction force accounts for 83 %–92 % of the resistance friction loss in the branch pipe section. Adding the U-shaped deflector can improve the synergy of the velocity and pressure gradient fields downstream of branch pipes and straight pipes, and reduce viscous dissipation. The total local resistance loss reduction rate of the novel tee is 83.15 %, the volume weighted average synergy angle is increased by 2.09°, and the viscous dissipation is reduced by 22.9 %.

Study on the Impact of Tail Wing Profiles on the Resistance Characteristics of Amphibious Vehicles

The resistance performance of amphibious vehicles can be improved by installing underwater tail hydrofoils. The research on the impact of different hydrofoil profiles on the resistance characteristics of amphibious vehicles can provide a reference for the vehicle’s design. For an amphibious vehicle model, five shapes of symmetrical hydrofoils, NACA0012, NACA0015, NACA0016, and asymmetric hydrofoils NACA23012, NACA66-209, were selected as the underwater tail wing of the vehicle body, respectively. Based on the RANS method and overset grid technology, the resistance performance of the vehicle body was numerically calculated, and the resistance variation in the amphibious vehicle equipped with different tail hydrofoils at 0.43 &lt; Fr∇ &lt; 1.3 speed was obtained. The basic shape of amphibious vehicle tail wings can be determined by comparing the effects of symmetrical hydrofoils and asymmetric hydrofoils on body resistance. The results show that the asymmetric hydrofoils have a better resistance reduction effect on amphibious vehicles than the symmetrical ones. Among them, an amphibious vehicle installing the asymmetric hydrofoil NACA66-209 as an underwater tail wing can reduce resistance by 44.3%. Chord length is an important factor affecting the resistance reduction performance of tail wings. When Fr∇ = 1.3, the asymmetric hydrofoil optimized based on chord length has a 21.2% higher resistance reduction effect on amphibious vehicles.

A low-resistance local component design method based on biomimicry and a random forest model: A pipe elbow case study

The energy consumption of building transmission and distribution systems accounts for more than 30% of building energy consumption, and the prevalence of localized components in building transmission and distribution systems leads to severe energy losses and resistance effects during system operation. To solve this problem, our research team has developed a series of resistance reduction components. This paper proposes a low-resistance local component shape optimization method based on biomimicry and machine learning, taking pipe elbows as an example, and the normalized shape optimization parameters of elbows with different pipe diameters are given. Through numerical simulation, full-size experiments, energy dissipation analysis and other methods, the optimized elbow resistance reduction effect and resistance reduction mechanism are verified and analyzed. The results showed that the resistance reduction rate of the elbow was 19%–26% for different pipe diameters and Reynolds numbers, and the optimized elbow significantly reduced energy dissipation during the flow process. Previously, the shape optimization problem of local components focused mainly on rectangular ducts that can be simplified in two dimensions; this study extends the optimization objective to circular pipes, which provides an effective method for guiding the optimal design of low-resistance local components in building transmission and distribution systems.

A dual-height wick to improve capillary performance of vapor chambers

The wick performance is a crucial metric for ensuring the reliable and efficient operation of vapor chambers (VCs) away from dry-out. To enhance the performance of VC, a pitcher plant inspired enhanced wick characteristic dual-height microgrooves (DHMW) was fabricated on 6063 aluminum alloy by one-step picosecond laser texturing without chemical modification. This study describes the two-step capillary behavior of DHMW by high-speed camera and infrared camera. The effects of minor rib number, groove height ratio, length scale, and test liquids (water, acetone, ethanol) on the capillary performance were investigated. When using water as the working fluid, the DHMW achieved a K/Reff of 1.182 µm, which was about 71.3 % larger than that of normal microgroove wicks due to the liquid propagation effect and the flow resistance reduction effect. Furthermore, the maximum K/Reff could reach 1.819 µm of the sample with a minor rib depth of about 70 μm. However, the wetting results showed that the droplets of acetone and ethanol tend to spread laterally after contact with the surface, which is unfavorable for the formation of hierarchical transport in the DHMW. This study demonstrates that laser texturing is an effective and controllable method for the complex shaping of grooved aluminum wicks, with the potential to improve the heat transport capability of VCs.

Research on the Resistance Reduction Law of Self-Excited a Resonant Circular Arc-Surface Bulldozing Plate Based on the Discrete Element Method

We explore the mechanism and law of reducing the resistance of soil cutting tools by achieving the self-excited vibration mode through the modification of the soil-engaging surface spectrum. Around the fundamental resonance point of the soil, and superimposing geometric waveforms of different spatial frequencies and amplitudes on the basis of the circular arc surface base directrix, 18 bulldozing plate models with different soil-engaging surface spectrum structures were designed and manufactured. By conducting a discrete element method (DEM) simulation of the working process of the bulldozing plate and comparing the working resistance of the soil-engaging components with the results of the soil bin test, the microscopic process of soil disturbance was further revealed from the perspective of simulation. The results indicate that the self-excited vibrating circular arc-surface bulldozing plate could effectively improve the resistance reduction effect during the operation around the resonance point. With this model, the average error of the horizontal working resistance was 7.52%, and the average error of the vertical working resistance was 21.71%. The analysis of the soil microscopic disturbance process by DEM simulation further verified the correctness of the macroscopic test results. The research work has an important reference value for both the vibration resistance reduction design of soil cutting tools and resistance reduction design of soil-engaging surfaces’ geometric structure modification.

Ship energy-saving device: Influence of the scale effect and hull roughness on the resistance reduction effect of an interceptor

Saving energy of ships are key research topics in the shipping industry, and the scale effect of energy-saving devices is a critical issue. Based on the Reynolds-averaged Navier–Stokes method, free-surface and double-body simulations of model- and full-scale ships were performed in this study. The resistance reduction effect and interceptor mechanism were analyzed. In addition, the influence of the scale and roughness effects on the resistance reduction performance of the interceptor was studied. The results showed that the stern flow field was significantly improved after the interceptor was installed, which was mainly responsible for the ship resistance reduction. When the Froude number ≥0.334, the average resistance reduction rates of the model- and full-scale interceptors were 5.67% and 8.71%, respectively. Some differences were observed between the extrapolated results of the resistance reduction effect of the interceptor and the results of the full-scale simulation; therefore, the change in the form factor and the scale effect of the wave-making resistance were considered in the extrapolated method. In addition, with increasing hull roughness, the frictional, viscous pressure, and total resistances of the ship increased, which decreased the resistance reduction rate of the interceptor by 1%–3% and shortened the resistance reduction speed range of the interceptor.

Effect of Starting Conditions on the Internal Flow Field and Interior Ballistic Performance of an Underwater Ventilated Launch

As one of the future main directions for underwater artillery, a ventilated launch can significantly reduce the huge water resistance during the underwater launching process. This paper aims to clarify the effect of starting conditions on the internal flow field and interior ballistic performance of an underwater ventilated launcher. Firstly, a three-dimensional unsteady model of gas–liquid two-phase flow is established. Following, an interior ballistic program of the underwater ventilated launch is developed. A coupling model between interior ballistic and gas–liquid interaction is then established, accounting for the projectile’s dynamic boundary effect and gas–liquid interaction. Subsequently, the simulation accuracy of the model is confirmed. Finally, the effect of parameter adjustments on the internal flow field and interior ballistic properties are contrasted and examined by altering the starting conditions. The results indicate that adjusting the gas injection pressure and projectile starting pressure can effectively regulate the drainage and resistance reduction effect, thereby obtaining the desired interior ballistic performance of the underwater ventilated launch. The findings offer recommendations for future underwater launchers.

Reduction of Alternating‐Current Resistance and Heat Generation of Spiral Inductors with Magnetic Sealing Technique

As direct current–direct current (DC–DC) converters increase their power density, their inductors require a planar structure with good heat dissipation. Planar inductors use rectangular wires or substrate patterns for their windings. Winding structures can be stacked, in which the structures are on top of each other; spiral, in which the windings are configured in the same plane; or composite structures of both. Here, the authors clarify the alternating‐current (AC) resistance of inductors with different winding structures and propose a magnetic sealing technique (MST) that reduces the AC resistance of low‐profile spiral inductors. Magnetic field simulation revealed the effect of MST on the AC resistance and inductance. Furthermore, spiral inductors with MST were fabricated, and the AC resistance reduction effect of MST was confirmed with impedance analyzer. The heat‐generation reduction effect in an MST inductor was demonstrated in a 1‐MHz 100 V/320 V 800‐W boost DC–DC converter prototype with GaN devices. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC.

An Experimental Study on the Resistance of a High-Speed Air Cavity Craft

For the marine industry, resistance reduction can reduce energy consumption and achieve protection of the marine environment. The use of air lubrication to reduce the resistance of ships is one of the most important ways. With this technology, high-speed air cavity crafts show immense potential as they can be utilized in various marine activities, such as emergency rescue, supply, and maritime security. Through experiments, this study presents an in-depth analysis of the effects of bubble chamber pressure and initial stern inclination on the resistance of high-speed air cavity crafts at different speeds. The results show that air pressure has a significant impact on resistance. It was found that as the speed of the ship increased, the resistance reduction effect became more prominent under the same pressure conditions. Moreover, the resistance tended to stabilize when the pressure reached a certain value. In addition to the air pressure, the longitudinal inclination does have an effect on resistance reduction. To achieve better resistance reduction, the initial stern inclination angle should be chosen appropriately. Furthermore, adjusting the angle with speed changes can optimize the resistance reduction effect. This experimental study provides critical support for conducting further research on high-speed air cavity crafts. The findings offer valuable insights into improving hull forms, guiding host selection, and assessing performance.

Self-Excited-Resonance of Soil-Engaging Surface Spectrum: A New Method of Soil Cutting Resistance Reduction

In this study we explored the methods and effects of spectral resistance reduction for soil-engaging surface of self-excited resonant bulldozing plates with a plane base on the basis of resonance effects. In the acquisition of the low-order vibration frequency f0 of the bin soil, centering around frequency point f0, eight spatial geometric wave frequency points ni of soil-engaging surfaces and three amplitudes were selected; by superimposing with soil-engaging surfaces of plane-based bulldozing plates, 24 spectral structures of the soil-engaging surface of bulldozing plates and model samples were combinatorically designed. Resistance reduction characteristics of each model sample were tested using an indoor soil bin test. Near the resonance point f0, the structures of the self-excited vibrating frequency spectrum of the soil-engaging surface obtain a preferable inhibitory effect on working resistance. At a 4 mm amplitude resonance point, model samples achieved the best resistance reduction effect, with a maximum relative resistance reduction rate of 22.67%, and the soil desorption effect of the relevant model sample was also good. On the other hand, away from the resonance point, whether the frequency increased or decreased, the corresponding working resistance of the model sample surfaces increased relatively. This is in good agreement with the law that the resonance point amplitude of the theoretical resonance curve is higher and the amplitude on both sides is lower. This paper provides a reference for the parameter design and related product development for various forced or self-excited vibration soil cutting tools.

Study on penetration resistance for thin-walled bucket foundation in muddy clay

In view of the problem that the resistance reduction effect of ring stiffeners is not considered in the existing calculation methods of penetration resistance, based on the field penetration date of thin-walled bucket foundation with ring stiffeners and combined with the field installation situation, the resistance reduction effect of the angle iron ring stiffeners on the skin friction resistance was explored, the calculation method of the penetration resistance considering the resistance reduction coefficient β was proposed. The results show that because the resistance reduction effect of ring stiffeners is not considered, the calculation results of the standard and theoretical equation method are larger than the measured resistance. The end resistance increased by ring stiffeners is about 55%–65% of the end resistance calculated by the standard and theoretical equation method, the end resistance increased by ring stiffeners should be considered in actual project. It is proposed that the calculation method considering the resistance reduction coefficient β can accurately predict the penetration resistance and the required differential pressure of bucket foundation with ring stiffeners, the recommended resistance reduction coefficient is 0.52 for the static penetration method, 0.33 for the undrained shear strength method, and 0.31 for the c and φ parameter method.

Low-resistance optimization and secondary flow analysis of elbows via a combination of orthogonal experiment design and simple comparison design

The resistance of local piping components in HVAC systems significantly contributes to building energy consumption. Therefore, this study proposes a method combining orthogonal experiment design (OED) and simple comparison design (SCD) to optimize the position and angle of the double guide vanes in the elbow, resulting in a low-resistance modified elbow with double guide vanes. The resistance performance and secondary flow intensity of the traditional and modified elbow with double guide vanes are analyzed by full-scale experiments and numerical simulations. The effectiveness of the modified elbow with double guide vanes in reducing resistance is verified for different inlet Reynolds numbers, nominal diameters, and curvature ratios. The results show that the modified elbow has a good resistance reduction effect, and the resistance reduction rate is 11.4%–29.4% when the Re number ranges from 0.1 × 105 to 8.0 × 105. Under different nominal diameters (DN25-DN200) and curvature ratios (0.8–2.0), the resistance reduction rate of the modified elbow was 0%–38.1%. For long elbows with a curvature ratio greater than 2.0, resistance reduction by inserting double guide vanes is not recommended. The insertion of double guide vanes can inhibit the development of secondary flow in the elbow, cutting the double-vortex core with high vortex intensity into a four-vortex core with low vortex intensity, thus decreasing the secondary flow intensity and mechanical energy consumption. This study provides new optimization methods and perspectives for the low-resistance and standardized design of piping components in HVAC systems.

Study on a tracked amphibious robot bionic fairing for drag reduction

In this paper, to reduce navigational resistance and energy consumption and to promote the efficiency of a novel track-propeller composite amphibious robot, a bionic fairing inspired by hammerhead sharks is proposed. Three types of fairing devices for underwater navigational resistance reduction are designed based on the bionic principle of hammerhead sharks. On this basis, the structural drag characteristics of four models, including an original model and three amphibious robot models with bionic fairings, are evaluated through computation fluid dynamics (CFD) analysis based on lattice Boltzmann method (LBM) theory. Experimental studies on the bionic fairing drag reduction of the amphibious robot model are conducted. In the experiments, the drag reduction effect of the bionic fairing devices is investigated considering two models and three speeds (0.5 m/s, 1.0 m/s, 2.0 m/s). Compared with the original model of the amphibious robot, the simulation and experimental results demonstrate that the bionic fairing devices inspired by the hammerhead shark head have a significant resistance reduction effect, the drag coefficient can be reduced by 23%, and the experimental results reveal a maximum drag reduction rate of 22%. This study provides an essential reference for the design of tracked amphibious robots with underwater navigation functions, reveals the drag reduction mechanism of the hammerhead shark head, and expands the bionic object of existing resistance reduction studies.

Seismic Damage Index Spectra Considering Site Acceleration Records: The Case Study of a Historical School in Kermanshah

The frequency content and time duration of earthquakes are as effective as the peak ground acceleration on structural damage. Therefore, using rapid seismic vulnerability assessment methods that consider the earthquake acceleration time history is noticeable. Kermanshah is a historical city that is generally affected by far-field earthquakes. Therefore, it is necessary to consider the effect of the low-frequency shocks in evaluating the vulnerability of buildings in this city. Herein, a historic school in Kermanshah is assumed as a case study and two well-known damage index formulas are used for determining the damage index spectra of this structure, considered as a single degree of freedom system. Then, the effective parameters of the damage index, including ductility, relative degradation of stiffness, and dissipated energy are determined from a nonlinear analysis of the structure under the effect of the most probable earthquake acceleration records. Finally, the damage index spectra can be used for rapid seismic vulnerability assessment of masonry buildings on similar sites with various fundamental periods for large-scale assessments. The result shows that the building tends to collapse at a peak ground acceleration of 0.15 g. Furthermore, results confirm the seismic resistance reduction effect of flexible floors.

Design of Energy-Saving Duct for JBC to Reduce Ship Resistance by CFD Method

The present work is to modify the stern duct of Japan bulk carrier (JBC) to reduce the ship total resistance for Froude number 0.142. The research method is to use the CFD (computational fluid dynamics) tool OpenFOAM to predict the total resistance and viscous flow field around the ship hull considering the free surface. First, the V&amp;V (verification and validation) analysis was conducted to ensure our CFD method is reliable, and to estimate its error and uncertainty range for the original JBC with and without the original stern duct. Second, the angle of attack (AoA) of the foil section of the stern duct was adjusted, thus forming a series of different ducts axisymmetric along the propeller shaft axis. The CFD simulations were performed for each duct appended behind the ship hull. By comparing the total resistance with and without the duct, the ship hull resistance reduction effect caused by the duct would be obtained. Finally, the duct with 7° AoA achieved the best resistance reduction of 2.49%. The original duct (with 20° AoA) could only provide a 0.6~0.7% reduction. The nominal wake was also analyzed with the ducts, in order to understand the detailed flow phenomena which had an essential influence on propeller inflow.