Cylinder Type Research Articles

Multiple-arc cylinder under flow: Vortex-induced vibration and energy harvesting

The shape of a cylindrical cross-section affects the vibrational performance. The vortex-induced vibration (VIV) phenomena of multiple-arc cylinders were numerically investigated to assess their impact on hydrodynamic energy harvesting and potential vibration suppression across a flow velocity range of 0.2 m/s to 1.4 m/s (1.767×104<Re<1.237×105). The study involves five types of multiple-arc cylinders: 4-arc, 8-arc, 16-arc, 24-arc, and circular cylinders. The accuracy of the numerical method was validated through comparison with experimental data. Specifically, increasing the number of arcs generally enhances overall energy conversion efficiency. Then, the VIV response and energy conversion results of the 24-arc cylinder are similar to those of the circular cylinder with maximum efficiency. Notably, the 4-arc cylinder achieves a global maximum amplitude of 0.074 m (A*=0.83) and a power output of 4.4 W with the new P+T mode, making it the most effective configuration for flow velocities between 0.7 and 0.9 m/s. For vibration suppression of multiple-arc cylinders, the appropriate arc structure effectively reduces amplitudes. The small vortices generated by the arc structures disrupt the separation of normal vortices from the boundary layer, leading to approximately a 50% reduction in amplitude responses for 8-arc and 16-arc cylinders.

A Constitutive Framework for Modeling of the Visco-Hyperelastic Materials: Application to the Mechanical Behavior of Cylinders Made of the Rate-Dependent Elastomers

In this paper, the formulation of the mechanical behavior of visco-hyperelastic materials is developed in a thermo-dynamically compatible framework. In this viewpoint, the stress power is assumed to be equal to the sum of the reversible (elastic) energy rate stored and the irreversible energy rate dissipated. Based on this assumption and using the second law of thermodynamics, the constitutive modeling framework is obtained for the rate-dependent materials. Inspired by the constitutive law of a Newtonian fluid and also, models of density strain energy of an elastic material, a framework for the dissipative energy rate related to the irreversible part is proposed for viscoelastic materials. In this framework, the reversible energy part is considered a function of the right Cauchy–Green deformation tensor, and the irreversible energy part is considered a function of the same tensor’s rate. To evaluate the proposed model for nonlinear viscoelastic behavior modeling, the results of tests performed on non-compressible materials at different rates are used, and the proposed model provided acceptable results. Finally, the proposed model is implemented to find a closed-form analytical solution for mechanical behavior modeling of the thick-walled cylindrical shells made of visco-hyperelastic materials, also, stress and stability analyses are assessed for these types of cylinders. To achieve this goal, the effect of pre-stretch on the stability of cylinders has been substantially investigated. Furthermore, based on the proposed model, the effect of the parameters such as the wall thickness and behavior of the material used in the cylinder are examined on the stability of open-ended and closed-ended cylinders.

Simulation study on hydraulic lifting mechanism of lift-sliding mechanical parking system

A mechanical parking system is an important parking equipment that can improve the utilization rate of urban space. In China, the lift-sliding mechanical parking system is the most widely used. Among many types of drives, the hydraulic pump-hydraulic cylinder type has advantages such as convenient system integration and expansion, energy saving, etc. The system is prone to vibration and pressure shock during operation. This paper focuses on the causes of vibration and hydraulic impact, constructs a simulation model, and analyzes the causes of vibration and hydraulic impact through simulation results, guiding equipment optimization.

Study of the Failure Mechanism of a High-Density Polyethylene Liner in a Type IV High-Pressure Storage Tank.

The use of Type IV cylinders for gas storage is becoming more widespread in various sectors, especially in transportation, owing to the lightweight nature of this type of cylinder, which is composed of a polymeric liner that exerts a barrier effect and an outer composite material shell that primarily imparts mechanical strength. In this work, the failure analysis of an HDPE liner in a Type IV cylinder for high-pressure storage was carried out. The breakdown occurred during a cyclic pressure test at room temperature and manifested in the hemispherical head area, as cracks perpendicular to the liner pinch-off line. The failed sample was thoroughly investigated and its characteristics were compared with those of other liners at different stages of production of a Type IV cylinder (blow molding, curing of the composite material). An examination of the liner showed that no significant chemical and morphological changes occurred during the production cycle of a Type IV cylinder that could justify the liner rupture, and that the most likely cause of failure was a design-related fatigue phenomenon.

Additively manufactured truss-core sandwich cylinders: Materials, processes and performances

To explore a structure with a superior load-to-mass ratio applying in rockets, two types of lattice truss sandwich cylinders with corrugated-core and X-core were designed, printed, tested and analyzed. The powder bed fusion (PBF) technique of laser additive manufacturing (AM) was applied to make the structures. Uniaxial compression results reveal that these truss-core sandwich cylinders have excellent mechanical performances with long plastic deformation, and their ultimate failure modes were global or local plastic post-buckling. The finite element method (FEM) was used to explore the influences of geometrical parameters to the failure mode and the bearing capacity. A failure theory was proposed, which can consistently predict the plastic buckling loads consistent with the experimental results. The load-to-mass ratio of the X-core cylinder is slightly about five percent improved compared to the corrugated-core cylinder, but the plastic plateau stage is greatly increased. Truss-core sandwich cylindrical shell configurations with high load-to-mass ratio, long plastic stage, easy-manufacturing and controllable process were successfully proposed for aeronautical structures through this research.

Research on the Vibration Reduction Performance of Swing Cylinder Type Hydro-pneumatic Suspension for Tracked Vehicles

Research on the Vibration Reduction Performance of Swing Cylinder Type Hydro-pneumatic Suspension for Tracked Vehicles

Numerical simulation study on the interaction between a gravity current and horizontal cylinders

Interactions between gravity currents and different types of horizontal cylinders are investigated, with a focus on analyzing the hydrodynamic characteristics of the flow field around the cylinders. The simulation results are compared with experimental measurements to verify the accuracy of the adopted numerical method. The hydrodynamic characteristics, including lift, drag, dynamic pressure and vorticity field around the cylinder, are analyzed. The results indicate that when the height of an individual cylinder increases, the vorticity in the flow field also increases. Additionally, the maximum dynamic pressure around the lower wall of the cylinder is significantly enhanced, which also leads to corresponding changes in the maximum force acting on the cylinder. Furthermore, the interaction between gravity currents and the double cylinder is studied. It can be found that the distribution of the maximum dynamic pressure and vortices around two cylinders relates to the change of the center-to-center distances. When the space is small, the drag force on the front cylinder is considerably smaller than that on an individual cylinder, and the center-to-center distance significantly affects the rear cylinder. The distribution of the maximum force on the cylinder is not obviously influenced by the changes in the cylinder's center-to-center distances.

Comparison of the Clinical Effectiveness of Correcting Different Types of Astigmatism with Small Incision Lenticule Extraction.

Few studies have reported the differential outcomes of Small Incision Lenticule Extraction (SMILE) on myopic astigmatism. Given this, we examined the effectiveness of SMILE for up to one year, comparing with-the-rule (WTR), against-the-rule (ATR), and oblique astigmatism, conducting a retrospective review of patients who underwent correction of myopic astigmatism using the 500-kHz VisuMax femtosecond laser (Carl Zeiss Meditec) at two refractive clinics in Poland between 2016-2017. Patients were aged ≥21 with stable refractive errors between -0.5 and -10.0 diopter (D) with astigmatism up to 5D. The mean age of the 209 patients (355 eyes) available was 32 years; 58.4% were female. Of these, 247 had WTR, 62 oblique, and 46 ATR astigmatism. The mean pre-operative spherical equivalent (SE) was -5.4 ± 2.57D and the cylinder -1.7 ± 1.0D. The mean SE for WTR reduced from -5.60 ± 2.37D to -0.31 ± 0.67D at 2 months and -0.38 ± 0.70D at 12 months; the mean cylinder improved from -1.90 ± 1.10D to -0.31 ± 0.39D and -0.36 ± 0.43D, respectively. Eyes with oblique astigmatism also improved from a mean SE of -5.8 ± 3.4 D to -0.82 ± 1.50D and -0.69 ± 1.15D and a cylinder of -1.4 ± 0.73D to -0.17 ± 0.33D at 2 months and -0.1 ± 0.32D at 12. For ATR, the mean SE improved from -4.0 ± 1.8D to -0.08 ± 0.22D and -0.04 ± 0.12D; and the mean cylinder from -1.25 ± 0.53 to -0.02 ± 0.09D -0.08 ± 0.21D at 2 and 12 months, respectively. There were statistically significant improvements in SE, manifest sphere and cylinder refraction, and UDVA and CDVA scores for each cylinder type at 2 months with ATR cylinders having better outcomes. Although missing data limited interpretation at one year, differences were maintained. The magnitude of error calculations suggests that WTR was more prone to under-correction, particularly for high astigmatism (>1.5D). SMILE for myopic astigmatism reliably corrects SE, irrespective of the subtype of astigmatism.

Compressive Performance of Longitudinal Steel-FRP Composite Bars in Concrete Cylinders Confined by Different Type of FRP Composites.

This paper presents an experimental study on the compressive performance of longitudinal steel-fiber-reinforced polymer composite bars (SFCBs) in concrete cylinders confined by different type of fiber-reinforced polymer (FRP) composites. Three types of concrete cylinders reinforced with (or without) longitudinal SFCBs and different transverse FRP confinements were tested under monotonic compression. The results showed that the post-yield stiffness of SFCBs is higher when confined with high elastic modulus carbon fiber-reinforced polymer (CFRP) composite than with low elastic modulus basalt fiber-reinforced polymer (BFRP) composite. Decreasing confinement spacing did not significantly improve the compressive strength of SFCBs in concrete cylinders. The compressive failure strain of SFCBs could possibly reach 88% of its tensile peak strain in concrete cylinders confined by CFRP sheets, which is significantly higher than the value (around 50%) in previous studies. Existing design equations, which applied a strength reduction factor or a maximum compressive strain of concrete to consider the compressive contributions of SFCBs in concrete members, underestimate the load-carrying capacity of SFCB-reinforced concrete cylinders. The design equation that considers the actual compressive stress of SFCBs gives the most accurate prediction; however, its applicability and accuracy need to be verified with more experimental data.

Numerical investigation of wave-cylinder interaction based on a momentum source wave generation method

A momentum source function is constructed for wave generation based on linear wave theory. Based on Navier-Stokes equation and volume of fluid (VOF) method, a three-dimensional numerical wave tank (NWT) is established. Regular and irregular waves can be simulated by applying the momentum source function to NWT, and the expected wave characteristic parameters and wave spectrum are obtained. Furthermore, the load characteristics of two types of cylinders, fully piercing cylinder (FPC) and truncated cylinder (TC), are studied under regular wave field combined with boundary data immersed method (BDIM). Results show that the transverse force exerted on cylinders is dominated by inertial force. And because of the effects of the cylinder on wave profile and drag force, the maximum transverse force occurs soon after the wave node passes through the centerline of the cylinder. Compared with the FPC, the drag force has a greater influence on TC.

Scattering characteristics of a perfect electromagnetic conducting cylindrical object covered with a general Bi-isotropic layer

Abstract An analytic theory has been developed for the scattering of electromagnetic plane wave from a perfect electromagnetic conducting (PEMC) cylindrical object coated with a general bi-isotropic (BI) material. The proposed problem has been solved using cylindrical vector wave function expansion approach along with the application of tangential boundary conditions. Analytic expressions of the scattering coefficients have been derived in their simplest forms. It is seen that by proper selection of admittance of PEMC core, electromagnetic parameters of BI coating, and coating thickness, one can optimize the scattering characteristics for specific applications. It is shown that the specific types of BI and strong chiral-coated PEMC cylinders having certain coating thicknesses can be used to significantly enhance the co-polarized forward scattering while keeping the cross-polarized forward scattering very small. Such types of enhanced co-polarized forward scattering are preferred in point-to-point communication. Some interesting features have been discussed where co-polarized and cross-polarized backscattering may be suppressed, which find applications in radar engineering problems and stealth technology.

Impact of high-speed turbidity currents on offshore spanning pipelines

Pipelines in the deep sea are at risk of damage due to submarine landslides, which can result in the loss of costly infrastructure and pollution stemming from hydrocarbon leaks. Submarine landslides can exhibit a wide range of flow characteristics, which in turn can affect how they interact with pipelines. Researchers have previously focused on pipelines impacted by submarine debris and/or mud flows described by non-Newtonian fluid rheological models and the laminar model. However, the impact of larger-scale and higher-speed submarine turbidity currents described by turbulence models on pipelines has been overlooked. In this study, we address this gap by utilizing a more accurate turbulence simulation method, namely, the large eddy simulation (LES) method, to analyze the effect of submarine turbidity currents on fixed spanning pipelines, and we validate the effectiveness of the proposed method via typical circular cylinder flow experiments and numerical simulations. We find that the lift force on the pipeline impacted by submarine turbidity currents under high-Reynolds number (Re) conditions is particularly significant relative to debris and/or mud flows under low-Re conditions. In parallel, the vortex shedding frequency increases with increasing Re, and the Strouhal number basically remains unchanged and ranges from 0.2–0.25 at 1,112 ≤ Re ≤ 333,559. Furthermore, the vortex structure and its arrangement behind the spanning pipeline become irregular with increasing Re, forming a turbulent vortex street, which reveals the mechanism of pipeline vibration. Finally, a methodology for predicting characteristic drag force and lift force coefficients is established for submarine pipeline design.

Experimental Study on Geopolymer Concrete with Waste Tiles Powder

While cement is not a green substance, the concrete industry is presently working toward creating sustainable concrete, employing industrial by-products to partially replace cementitious ingredients. To replace cement, the creation of eco-friendly concrete is facilitated using industrial wastes in geopolymer concrete (GPC), which also encourages waste recycling. Fly ash geopolymer has been utilized as a replacement for traditional cement concrete. An environmentally friendly and economically advantageous substitute for conventional concrete is geopolymer concrete with ceramic tile waste powder. To identify some superior alternatives for making GPC, the present study includes an experimental investigation on the compressive strength of GPC created from various other options and quantities of Fly ash and wastage tiles powder. Another focus of this research is on eliminating environmental waste for a better society. In this study, nine distinct types of concrete cylinders were produced, each with 5%, 10%, and 20% of fly ash replaced with GCV (Geopolymer Concrete with Vitrified Tile Powder) and GCW (Geopolymer concrete with wall tiles powder), respectively. Even though the replacement percentages are not so high, they do matter in terms of maintaining a sustainable, environmentally friendly workplace and managing waste. Additionally, geopolymer concretes are made without the use of heat curing, which encourages sustainability in the generation of thermal energy.

Feasibility of the preparation of cochleate suspensions from naturally derived phosphatidylserines.

Cochleates are cylindrical particles composed of dehydrated phospholipid bilayers. They are typically prepared by addition of calcium ions to vesicles composed of negatively charged phospholipids such as phosphatidylserines (PS). Due to their high physical and chemical stability, they provide an interesting alternative over other lipid-based drug formulations for example to improve oral bioavailability or to obtain a parenteral sustained-release formulation. In the present study, the feasibility to prepare cochleate suspensions from soy lecithin-derived phosphatidylserines (SPS) was investigated and compared to the "gold standard" dioleoyl-phosphatidylserine (DOPS) cochleates. The SPS lipids covered a large range of purities between 53 and >96% and computer-controlled mixing was evaluated for the preparation of the cochleate suspensions. Electron microscopic investigations were combined with small-angle x-ray diffraction (SAXD) and Laurdan generalized polarization (GP) analysis to characterize particle structure and lipid organization. Despite some differences in particle morphology, cochleate suspensions with similar internal lipid structure as DOPS cochleates could be prepared from SPS with high headgroup purity (≥96%). Suspensions prepared from SPS with lower purity still revealed a remarkably high degree of lipid dehydration and well-organized lamellar structure. However, the particle shape was less defined, and the typical cochleate cylinders could only be detected in suspensions prepared with higher amount of calcium ions. Finally, the study proves the feasibility to prepare suspensions of cochleates or cochleate-like particles directly from a calcium salt of soy-PS by dialysis.

3S consideration (Synthesis, Surfactant, and Sonication) for stability and thermophysical properties enhancement of alumina-water nanofluid

Nanofluid (NF), a homogeneous dispersal of nanoparticle (NP)s in a carrying fluid, is used in many thermal applications due to its exceptional thermal characteristics. The goal of the current study is to use two-step technique for development of stable aqua alumina NF. The NF's stability is increased by using cetyltrimethylammonium bromide, a cationic surfactant. Magnetic stirring with heating is used to improve nanoparticles dispersion in the base fluid (BF). Following the development of the NF, the synthesised sample is examined utilising several stability evaluation procedures at various time intervals, including 1 day, 8 days, 15 days, and 30 days. Utilising modern equipments such as KD2Pro analyzer and double gap rotating cylinder type viscometer, thermophysical properties as thermal conductivity (knf) and viscosity (μnf) of NF were evaluated. According to experimental findings, enhancement in the volume fraction of NPs was accompanied by an increase in the nanofluid’s thermophysical properties. At the highest volume concentration, the highest augmentation in knf and μnf was found as 8.52% and 76.21%, respectively.

Convective heat transfer enhancement by corona discharge in a wire–cylinder electrostatic precipitator with the water-cooling system

Aiming at the current wet plume problem, we present a novel technique to integrate electrostatic precipitator (ESP) and heat exchanger in order to simultaneously increase heat exchange efficiency, collect water and control particle emission from flue gases. Unlike the conventional ESP, a lab-scale wire–cylinder type ESP with the collection electrode cooling by water is used for investigations in this paper. Our research indicates that the heat transfer coefficient of the ESP rises with reducing gaseous velocity, increasing applied voltage, corona current or gas temperature. The maximum improvement of the total heat transfer coefficient of 271% was achieved at 0.15 m/s, 80 °C and 16 kV of the negative discharge. Moreover, the presence of Particle matters can enhance the heat transfer coefficient by 9%–16%. The ionic wind, which is quantitatively expressed by electro-hydrodynamic number, plays a key role in modifying the gas flow patterns and consequently improving the heat exchange coefficient. For lowering the overall energy consumption, it is suggested that the ESP should be operated at a specific mode of low voltage and high current.

Development of a hand classification system for smart hand wearables

Research purpose: This study aimed to lay a research foundation for smart hand wearable design by classifying the right-hand data of 4545 adults aged 20 to 69. Further, to increase the practical applicability of the hand classification system, a hand type discrimination method and regression equations for the hand dimensions of each type were presented. Methods: This study statistically analyzed eighth Size Korea data with IBM SPSS Ver.26.0. Cluster analysis was performed to classify both finger length and circumference type. Discriminant analysis was conducted, yielding discriminant functions to aid potential smart hand wearable wearers in self-diagnosing their hand types. Linear regression analysis yielded regression equations for the detailed finger dimensions for the pattern-making of smart hand wearables. Results: The finger length type was categorized into four types: the Uphill type, Downhill type, Mountain type, and Horizon type for both men’s and women’s hands. The finger circumference type was categorized into two types, the Cone and Cylinder types, for both men’s and women’s hands. The discriminant function showed a mean accuracy rate of 89.9% and the regression equations a mean explanatory power of 72.9%. Conclusion: The hand classification system proposed in this study aimed to improve the fingertip fit of smart hand wearable products by analyzing the configuration of motion tracking gloves or haptic gloves. In addition, considering the practical applicability for both wearers and designers of smart hand wearables, a discrimination method of finger types for wearers’ self-diagnosis and regression functions of finger dimensions for designers’ pattern making were provided.

6 Characterization of Aerosolized Particles Generated During Cutting of Carbon Nanotubes-Embedded Concrete

Abstract Engineered nanomaterials are revolutionizing many industries, but little is known about potential exposures during the life cycle of nano-enabled composites. This study was conducted to characterize aerosolized particles using direct-reading instruments and integrated air samplers during cutting multi-walled carbon nanotubes (MWCNT)-embedded concrete cylinder blocks. Three types of blocks, 0% (reference), low%, and high% MWCNT, were tested in a specially designed enclosure housing an apparatus for the cutting of a block with an automated computer-controlled process. The highest particle number concentration (163,821 particles/cm3) was measured for the reference cylinder, while others showed similar concentrations (131,689 particles/cm3 and 140,954 particles/cm3 for the low% and high% blocks, respectively). Regardless of the cylinder type, the size-selected particle number concentrations revealed one main mode with a peak at 0.72 µm indicating no shift in the size distribution from addition(s) of MWCNT. Respirable mass concentrations were 342 mg/m3, 405 mg/m3, and 432 mg/m3 for the reference, low%, and high% blocks, respectively. The mass median aerodynamic diameters were similar, 5.23 µm for the reference and 5.05 µm for both low% and high% blocks, indicating a predominant respirable fraction. Respirable particles (quartz, feldspar, paste, etc.) often appeared to be agglomerated materials that included both paste and aggregate minerals. No free MWCNT were observed by electron microscopy from low% and high% samples. These initial studies found no evidence of free MWCNT by cutting concrete test blocks and only minor differences in the particulate aerosol generated, which included a general increase in respirable mass with increasing % CNT.

Analisis Kinerja Alat Raosting Kopi Kapasitas 2kg Tipe Silinder Horizontal

Roasting is a process of frying coffee without oil using high temperatures which aims to speed up the process of frying coffee beans. The coffee roasting process aims to form the taste and aroma of the coffee beans. The coffee roasting equipment used in this study was a horizontal cylinder type coffee roaster with a capacity of 2 kg. This machine rotates with an electric dynamo. It has a cylindrical tube with a length of 27.5 cm and the heat comes from an LPG (Liquefied petroleum gas) stove. The purpose of this research is to test the performance of coffee roasting equipment. The data that needs to be measured from this coffee roasting tool is the need for electrical power used, roasting capacity and the change in color of the coffee when it is roasted. The electric power used is 12 volts 15 amperes. The results of the dark roast test at 200°c at 21 minutes. The maximum capacity of this horizontal cylinder type roasting machine is 2 kilograms

Harvesting and Threshing Methods for Paddy-II: A Review

Threshing of paddy crop is carried out using manual, animal or mechanized power sources depends on the farmland size. In a thresher, rasp bar, spike tooth, peg tooth and wire-loop type threshing elements can be fitted with the threshing cylinder irrespective of direction of crop feed and flow. Different elements are responsible to thresh the crop with different actions which include impact, rubbing, combing, squeezing and their combination. This review was carried out to explore the effect of different threshing elements and threshing methods on performance of paddy threshing. Unlike threshing of other cereal crops, hull removal is not required in paddy. Selection of threshing elements based on the crop to be threshed. The type of threshing element determines the threshing efficiency, energy requirement and grain loss. Among rasp bar, spike tooth, peg tooth and wire-loop type threshing elements, wire-loop type was found to be most suitable for paddy threshing. Factors like cylinder speed, cylinder type and diameter, concave clearance and throughput rate affect the threshing performance. A low speed of cylinder produces more un-threshed grains. It can be compensated using for axial flow thresher as it has high crop retention period. Contrarily, a high speed is responsible for better threshing efficiency along with the more grain breakage and energy consumption. Using tangential flow thresher crop retention period can be minimized. The work rate of pedal and power thresher was, respectively 2 and 10 times more than that of manual threshing. The average threshing efficiency of pedal thresher, power thresher and combine harvester was reported to be 97 to 99%, 96.30 to 99.75% and 98.5%, respectively.