Cylinder Type Research Articles

Forecast flexural strength of pervious concrete by SVR

For the development of construction technology, pervious concrete is vastly using in road infrastructure. Pervious concrete has a strong drainage ability that can recharge groundwater, made by the coarse aggregate, water, and cement with little fine aggregate or without fine aggregate. The compressive and flexural strengths of pervious concrete are vital parameters to identify the concrete quality and also necessary in the process of analysis and design of a concrete infrastructure. This research represents a system for forecasting the flexural strength obtained from the compressive strength (0 up to 30 MPa) of concrete cube and cylinder types specimens by support vector regression (SVR) for both 7 and 28 days. Experimental data from various literature have been collected to formulate the model. It appears that the relationship between the compressive strength and flexural strength of pervious concrete is non-linear. The linear models developed with limited lab test found ineffective when they are subjected to wide range of data set for flexural strength prediction. In this study, all compared models and developing model’s effectiveness are examined based on R2, RMSE, MAPE, MSE, and IAE parameters for both 7- and 28-days specimens.

A Calibration Method of Phase Error Caused by Target’s Position Error

A method is proposed in this paper to correct the position error in radar cross section (RCS) calibration. In radar RCS measurement system, in order to get the accurate information, the amplitude and phase calibration are very important to remove the error influence. The measurement results are influenced by multipath effect, laboratory background, target position, environmental noise and so on. In this paper, the position error correction is under consideration. Firstly, the method of getting target position is derived. Following this, the phase error caused by it can be got rid of to get more accurate data. Finally, we show the extensive simulation results and experiment results of typical cylinder, which all demonstrate the validity of the method.

Study on Dose Rate on the Surface of Cask Packed with Activated Cut-off Pieces from Decommissioned Nuclear Power Plant

Background: Reactor pressure vessel (RV) with internals (RVI) are activated structures by neutron irradiation and volume contaminated wastes. Thus, to develop safe and optimized disposal plan for them at a disposal site, it is important to perform exact activation calculation and evaluate the dose rate on the surface of casks which contain cut-off pieces. Materials and Methods: RV and RVI are subjected to neutron activation calculation via Monte Carlo methodology with MCNP6 and ORIGEN-S program—neutron flux, isotopic specific activity, and gamma spectrum calculation on each component of RV and RVI, and dose rate evaluation with MCNP6. Results and Discussion: Through neutron activation analysis, dose rate is evaluated for the casks containing cut-off pieces produced from decommissioned RV and RVI. For RV cut-off ones, the highest value of dose rate on the surface of cask is 6.97 × 10-1 mSv/hr and 2 m from it is 3.03 × 10-2 mSv/hr. For RVI cut-off ones, on the surface of it is 0.166 × 10-1 mSv/hr and 2 m from it is 1.04 × 10-1 mSv/hr. Dose rates for various RV and RVI cut-off pieces distributed lower than the limit except the one of 2 m from the cask surface of RVI. It needs to adjust contents in cask which carries highly radioactive components in order to decrease thickness of cask. Conclusion: Two types of casks are considered in this paper: box type for very-low-level waste (VLLW) as well as low-level waste (LLW) and cylinder type for intermediate-level waste (ILW). The results will contribute to the development of optimal loading plans for RV and RVI cut-off pieces during the decommissioning of nuclear power plant that can be used to prepare radioactive waste disposal plans for the different types of wastes—ILW, LLW, and VLLW.

3D morphological classification of the nasolacrimal duct: Anatomical study for planning treatment of tear drainage obstruction.

The purpose of this study is to analyze and classify morphological features of the nasolacrimal duct (NLD) through 3D reconstruction to help understand the causes and treatment of NLD obstruction. In this study, we included 63 males and 55 females who underwent autopsy without NLD obstruction with ages ranging from 20 to 78 years. The NLD was defined from the lacrimal fossa to the opening of the BNLD to the inferior meatus, and all continuous CT images showing the NLD were selected. Segmentation was performed semi-automatically, and the reconstruction and measurement of NLD was performed using the Mimics program. Overall NLD length, bony nasolacrimal duct (BNLD) length, anteroposterior and transverse diameters at the entrance to the BNLD, anteroposterior and transverse smallest diameters of the BNLD, BNLD volume, and lacrimal sac BNLD angle were significantly higher in males than females (p < .05). BNLD direction in the coronal plane was slightly more likely to be inward. The most common type in both sexes was cylinder type (42.0%), males were more likely to have lower-thicker types (34.1%), and females more likely to have upper-thicker types (22.7%). There were sex differences in NLD measurements, and females had significantly smaller NLDs. These results may partially explain the increased prevalence of primary acquired NLD obstruction in females. The BNLD tends toward the midline, and inclines posteriorly.

Performance of paddy dryer with screw conveyor assisted parabolic cylinder collector as thermal generator

Objectives: This study aims to develop better solar dryer for paddy drying. Methods and Analysis:The design and fabrication of a parabolic cylinder type collector-drying unit has been developed. Paddy is dried by the variation which took place into four batches starting from batch 1 (08:30 - 09:20), batch 2 (09:30- 10:10), batch 3 (10:20 - 11:10) and batch 4 (11:40 - 12:20) Western Indonesia Time (GMT +7), with a capacity of 5 kg of paddy/batch and solar radiation is in the range of 408.5 - 547.2 Watt/m2. The highest irradiation takes place in batch 2 with the maximum temperature inside the dryer reaching 74◦C. Findings: Overall the experiments achieved that paddy temperature are in the range of 43 – 45◦C, with the shortest drying time achieved in batches 2 and batch 4 i.e. 40 minutes. Thermal efficiency are in the range of 37.91% - 50.35%, SEC of 5.318 - 7.042 MJ/kg H2O evaporated and drying rate of 1.06 - 1.38 kg/hrs. Thus, this solar dryer is more effective than industrial inclined bed dryer or theindustrial horizontal rotary dryer. Novelty: The solar dryer using a parabolic cylinder type solar collector with a screw conveyor has been designed which can reduce drying time and moisture content better. Keywords: Solar dryer; parabolic collector; paddy; efficiency

Residual stress and deformation analysis on thermal shrink-fitted joint in the semi built-up marine crankshaft

Interference and deformation of the shrink fitting connection have a significant influence on the local stress state at the contact area. To improve its assembly quality, an optimized induction heating method with an arc-shaped frame coil and a cylinder type coil was developed. The effects of shrink fitting parameters such as residual contact stress and dimensional deformation were researched using finite element analysis (FEA). A thermal-structure coupling model of crankshaft shrink fitting was built, and contact stress evaluations of the measurement points in the shrinkage were obtained by numerical simulation. In addition, contact stress and deformation analysis under different interferences were also carried out to determine the range of values. The simulation and comparative analysis results show that the optimized multiple induction heating method with an arc-shaped frame coil and a cylinder type coil would be helpful to improve the uniformity and sustainability of contact.

A Real-Time Detection System for the Onset of Parametric Resonance in Wave Energy Converters

Parametric resonance is a dynamic instability due to the internal transfer of energy between degrees of freedom. Parametric resonance is known to cause large unstable pitch and/or roll motions in floating bodies, and has been observed in wave energy converters (WECs). The occurrence of parametric resonance can be highly detrimental to the performance of a WEC, since the energy in the primary mode of motion is parasitically transferred into other modes, reducing the available energy for conversion. In addition, the large unstable oscillations produce increased loading on the WEC structure and mooring system, accelerating fatigue and damage to the system. To remedy the negative effects of parametric resonance on WECs, control systems can be designed to mitigate the onset of parametric resonance. A key element of such a control system is a real-time detection system, which can provide an early warning of the likely occurrence of parametric resonance, enabling the control system sufficient time to respond and take action to avert the impending exponential increase in oscillation amplitude. This paper presents the first application of a real-time detection system for the onset of parametric resonance in WECs. The method is based on periodically assessing the stability of a mathematical model for the WEC dynamics, whose parameters are adapted online, via a recursive least squares algorithm, based on online measurements of the WEC motion. The performance of the detection system is demonstrated through a case study, considering a generic cylinder type spar-buoy, a representative of a heaving point absorber WEC, in both monochromatic and polychromatic sea states. The detection system achieved 95% accuracy across nearly 7000 sea states, producing 0.4% false negatives and 4.6% false positives. For the monochromatic waves more than 99% of the detections occurred while the pitch amplitude was less than 1/6 of its maximum amplitude, whereas for the polychromatic waves 63% of the detections occurred while the pitch amplitude was less than 1/6 of its maximum amplitude and 91% while it was less than 1/3 of its maximum amplitude.

Mechanism Modeling and Simulink Simulation Analysis of Digital Hydraulic Cylinder

Based on the structure of the digital hydraulic cylinder and the principle of closed-loop control, the mechanism models of the stepper motor and the spool mechanism, the three-way spool valve, and the hydraulic cylinder are established respectively, and the overall mathematical model of the digital hydraulic cylinder is synthesized, and its Simulink simulation model is constructed. The stability and positioning accuracy of the system are analyzed. The results show that the error of this type of digital hydraulic cylinder is 0.0142mm for 1mm action and 0.0182mm for 2mm action. At the same time, it is found that the fluctuation of oil supply pressure will cause system jitter and reducing the frequency of stepper motor can improve the positioning accuracy of the cylinder.

UJI LAPANG MESIN PENGOLAHAN SAGU PRODUKSI BENGKEL PERMESINAN AGROINDUSTRI UNIVERSITAS PAPUA

Papua and West Papua Province have the large potential of sago palm (Metroxylon sagu), however, until now the production and utilization is very low compared with its potential. This is because of most farmers in this area still use traditional method in processing sago. The traditional method is labour intensive and time consuming process. Sago farmers in this area still apply traditional ways to process sago starch due to the lack of processing machines. The objective of this research was to conduct field testing of sago processing machine produced by Agroindustry Machinery Workshop of Papua University. The machines that have been tested consist of cylinder type sago rasping machine and stirrer rotary blade sago starch extraction machine. The machine’s performance under field condition was evaluated by measuring parameters (a) rasping capacity, (b) extraction capacity, (c) starch percentage, (d) starch yield and (e) starch loss in waste. Results showed that all parts of the machine are functioning properly and farmers can easily operate the machine. The performances of the machines under field condition were (a) rasping capacity 1,159. 8 kg/hour, (b) extraction capacity 243.8 kg/hour, (c) starch percentage 38.26 %, (d) starch yield 93 kg/hour and (e) starch loss in waste 1.03 %. Keywords: cylinder type, field test, rasping machine, sago processing, starch percentage

Haemodynamics around confined microscopic cylinders

Motivated by the recent developments in the research of untethered microrobots for performing minimally invasive procedures inside blood vessels, we have devised a novel microfluidic experiment for studying the haemodynamics around different types of cylinders confined inside a straight, long, 270×100μm channel. Two test sections are studied: flow past a confined circular cylinder and past a confined elliptic cylinder. The two cylinders cause a channel blockage of about 28%. We consider a continuous regime for the blood flow, since its pulsatile nature is barely felt in the regions of the human body further away from the heart, and Reynolds numbers (Re) in the range of 0.05–100, which allow to replicate a variety of flow conditions. Human blood is emulated using non-particulate polymer solutions with rheological properties analogue to those of the biofluid. Pressure drop measurement, micro-Particle Image Velocimetry and streak imaging techniques are employed to study the viscoelastic haemodynamics in the test sections, characterised by elasticity numbers (El) in the approximate interval of 1–30. Our findings include a striking dampening effect on the acceleration of the flow in the contractions between the elliptic cylinder and the channel walls, due to the elasticity of blood, and steeper pressure drops and longer recovery lengths measured in the test section of the elliptic obstacle, caused by a stronger shear stress field characterising this flow geometry and higher strain accumulation in its wake, respectively, compared to the circular cylinder.

The effect of porosity on the drag of cylinders

Abstract

Overall flow dynamics characteristics of slit-vent cylinders

PIV (Particle Image Velocimetry) experiments were conducted to reveal the influence of the Reynolds number (Re), position, and inclination angle of a slit vent on the overall flow dynamics characteristics of slit-vent cylinders. The flow mechanism of the slit vent was studied based on the quantitative evaluation of the periodic shedding vortex transformations. The experimental results indicated that the slit vent could produce a strong effect of blowing and suction on the boundary layer if the slit-vent position was in front of the flow separation point for the base cylinder. The effect of the blowing and suction caused the Kármán vortex street (KVS) to occur much earlier and strengthened the vortex shedding for the 120° and 180° slit-vent cylinders. The St values of the 180° slit-vent cylinders were least sensitive to Re as compared with the other cylinder types with Re = 2000 ∼ 5400. With the slit-vent inclination angle β varying in the range of 80°–90°, the St values of the 180° slit-vent cylinder were around 0.225 and exhibited the greatest stability.

Experimental study on the interaction between turbulent boundary layer and wake behind various types of two-dimensional cylinders

The interaction between the turbulent boundary layer and wake behind various types of two-dimensional cylinders is examined based on the velocity measurements by hot-wire anemometry and particle image velocimetry. Three types of cylinders, such as circular, square, and 1:5 rectangular cylinders, of two different diameters of 5 ​mm and 10 ​mm were employed in this study. The streamwise velocity distributions of the wake flow showed that its width is sustained in the streamwise direction within the boundary layer because of its interaction with the turbulent boundary layer flow. Interestingly, this phenomenon was observed regardless of the cylinder shapes. The momentum exchange in both spanwise and vertical directions showed that the advective momentum flux considerably contributes to momentum budget in the wake flow owing to the weak vertical flow formed within the boundary layer. Consequently, the spanwise width of the wake does not expand in the streamwise direction due to the alternation of the momentum budget. The results of this study can contribute to clarifying the effect of interaction between the wake and the turbulent boundary layer, as well as explain the sustaining mechanics of the low speed streaks formed within the turbulent boundary layer, even for different origins of the low-speed regions.

High energy density storage of gaseous marine fuels: An innovative concept and its application to a hydrogen powered ferry

The upcoming stricter limitations on both pollutant and greenhouse gases emissions represent a challenge for the shipping sector. The entire ship design process requires an approach to innovation, with a particular focus on both the fuel choice and the power generation system. Among the possible alternatives, natural gas and hydrogen based propulsion systems seem to be promising in the medium and long term. Nonetheless, natural gas and hydrogen storage still represents a problem in terms of cargo volume reduction. This paper focuses on the storage issue, considering compressed gases, and presents an innovative solution, which has been developed in the European project GASVESSEL® that allows to store gaseous fuels with an energy density higher than conventional intermediate pressure containment systems. After a general overview of natural gas and hydrogen as fuels for shipping, a case study of a small Roll-on/Roll-off passenger ferry retrofit is proposed. The study analyses the technical feasibility of the installation of a hybrid power system with batteries and polymer electrolyte membrane fuel cells, fuelled by hydrogen. In particular, a process simulation model has been implemented to assess the quantity of hydrogen that can be stored on board, taking into account boundary conditions such as filling time, on shore storage capacity and cylinder wall temperature. The simulation results show that, if the fuel cells system is run continuously at steady state, to cover the energy need for one day of operation 140 kg of hydrogen are required. Using the innovative pressure cylinder at a storage pressure of 300 bar the volume required by the storage system, assessed on the basis of the containment system outer dimensions, is resulted to be 15.2 m3 with a weight of 2.5 ton. Even if the innovative type of pressure cylinder allows to reach an energy density higher than conventional intermediate pressure cylinders, the volume necessary to store a quantity of energy typical for the shipping sector is many times higher than that required by conventional fuels today used. The analysis points out, as expected, that the filling process is critical to maximize the stored hydrogen mass and that it is critical to measure the temperature of the cylinder walls in order not to exceed the material limits. Nevertheless, for specific application such as the one considered in the paper, the introduction of gaseous hydrogen as fuel, can be considered for implementing zero local emission propulsion system in the medium term.

Experimental investigation on ignition, combustion and micro-explosion of RP-3, biodiesel and ethanol blended droplets

Based on an infusion set, measuring cylinder and different types of micro needles, a method for measuring the volume of micro-droplet was established. The same volume of aviation fuel (RP-3), biodiesel and ethanol mixed droplets were sent to a heatable experimental device to study the combustion characteristics. Through a movable slide rail with adjustable speed, the mixed droplets suspended on the high-temperature resistant wire were transported to a distance of about 2 mm from the preheating plug for heating. The ingle-lens-reflex (SLR) camera and a high-speed camera were used to capture the ignition characteristics and instantaneous combustion characteristics of mixed droplets during heating, respectively. The burning mixed droplets video captured by the SLR camera was processed into color pictures by Adobe Premiere Pro CC software. Through the processing and analysis of these images, the ignition, combustion and micro-explosion characteristics of mixed droplets during combustion were studied. The equation for calculating the micro-explosion intensity was established, the micro-explosion intensity of binary mixed droplets and ternary mixed droplets was calculated and analyzed.

Experimental study on wake flow structures of screen cylinders using PIV

Experiments were conducted in a water flume using Particle Image Velocimetry (PIV) to study the evolution of the vortical structures in the wakes of four types of screen cylinders at a Reynolds number of about 3200. The results were compared with that of a bare cylinder. The screen cylinders were made of stainless steel screen meshes of various porosities (37%, 48%, 61% and 67%) rolled into cylindrical shapes. Smoke wire flow visualisations in a wind tunnel were also conducted in support of the PIV tests. Depending on the porosity of the screen mesh, two vortex formation mechanisms for the screen cylinder wakes were identified. One was associated with wake instability and the other was associated with shear-layer (Kelvin-Helmholtz) convective instability which involved merging through pairing and tripling of small-scale vortices within the shear layers. The former was responsible for the formation of large-scale vortices in the bare cylinder and the screen cylinder wakes with 37% and 48% porosities, while the latter was responsible for the screen cylinder wakes with 61% and 67% porosities. The results also showed that with increasing porosity, the vortex formation region was extended farther downstream and the Reynolds shear stress, the Turbulent Kinetic Energy (TKE) and vortex intensity were decreased constantly.

Electrospun Highly Crystalline ZnO Nanofibers: Super‐Efficient and Stable Photocatalytic Hydrogen Production Activity

AbstractZnO has tremendous potential in photocatalysis, but only has moderate activity and poor stability because of the sluggish charge transfer and easy aggregation problem, respectively. In this work, ZnO photocatalyst with well‐defined one dimensional (1D) nanofiber structure was successfully fabricated for overcoming these defects. The results revealed that the ZnO nanofibers consist of compactly packed particles that form a cylinder type fiber in highly crystalline and high purity. The robust 1D nanostructure not only can suppress the aggregation of nanoparticles, but also facilitate the interparticle charge transfer. Besides, the mesoporous structure generated through the ZnO particle‐particle interconnection can promote the adsorption of reactants and desorption of products. Benefiting from these merits, the ZnO nanofibers photocatalyst presented superior higher and stable hydrogen production ability than that of nanoparticles counterpart. The photocatalytic hydrogen generation rate of the ZnO nanofibers was estimated to be 1031.8 μmol g−1 h−1, which was about 1.5 times higher than that of ZnO nanoparticles. Moreover, the ZnO nanofibers photocatalyst can maintain its 93.2 % H2‐production rate after five recycle experiments, whereas only 55.8 % for ZnO nanoparticles. This study provides an effective way to solve the energy problem by using solar energy.

Differential volumetric analysis combined with monitoring of differential ultra-sound travel time, an approach for tracing fine-structural compression behaviour of solids: a study on MgO / periclase and polyethylene / PE up to 1.5 GPa at room temperature

The study addresses the topic of fine-structural compression behaviour of solids. MgO / periclase and polyethylene / PE are studied as exemplary materials by volumetric and ultra-sound techniques at room temperature up to 1.5 GPa. The experiments conducted with a high-pressure device of the piston cylinder type rely on: (a) measurements of the piston displacement performed under continuously changing uniaxial load in combination with (b) simultaneous monitoring of the travel time of ultra sound. Both methods base on differential technique implying that all data are of relative nature. The volume-density relation (Δρ = Mconst / ΔV) is the fundamental relation which provides information on compressional as well as on acoustic behaviour of the sample. It serves, additionally, as mutual control of the observations. The data evaluation bases on the method of difference calculation: the data obtained from a run with sample [sample + (vessel + piston assembly)] are subtracted from those of a calibration run [(vessel + piston assembly)]. In most cases the differences retrieved are small and may be presented best in form of derivatives with respect to pressure. The compression behaviour of MgO under hydrostatic conditions is reported to be quasi-linear up to about 2 GPa. Under the uniaxial load exerted by the piston cylinder apparatus MgO reveals a compression behaviour characterized by two volumetric anomalies at 400 and at 1000 MPa. The ultrasonic measurements suggest that shear plays an important role. Comparative measurements on the visco-elastic material polyethylene corroborate that interpretation.

Study on fatigue crack growth rate of 15CrMo steel based on stress ratio and corrosion environment

In this paper, the fatigue crack growth rate of 15CrMo steel, a typical gas cylinder material, is studied under the condition of simulating the actual working condition of gas cylinder. The low-frequency corrosion fatigue tests with stress ratio of 0.1 and 0.5 are carried out in air and different concentrations of wet hydrogen sulfide environment. The relationships between da/dN and ΔK are expressed by Paris equation. The results show that the crack growth rate in hydrogen sulfide environment with concentration of 200 ppm is 27 times higher that in air. The addition of corrosion environment greatly fasts the crack growth rate of 15CrMo steel. With the increase of H2S concentration, the crack growth rate increases exponentially. With the increase of stress ratio, the average stress increases, the crack closure effect decreases, the crack tip is fully opened, and the contact area with corrosion medium increases, which results in the increase of crack growth rate.

An analytical approach to evaluate the maximum load carrying capacity for pin-mounted telescopic hydraulic cylinder

The hydraulic cylinder is an actuating mechanical maneuver used to transfer the power from one station to another. For industrial purposes, various types of cylinders are employed as per the requirement. Telescopic hydraulic cylinder, also known as the two-stage hydraulic cylinder is one of the widely used hydraulic cylinders in the industry. The closed center length of a telescopic cylinder is 20% to 40% of the open center length depending on the number of stages. The safe operation of such telescopic hydraulic cylinder is highly essential. One of the prominent failures includes the buckling failure of the hydraulic cylinder. Once the system fails, the operating parameters change abruptly and thus the proper working gets affected. In literature, there is no significant standard that governs the buckling load determination of two-stage hydraulic cylinder. Existing technical standard ISO/TS 13725 : 2016 approach is only prescribed for the single-stage cylinder. In this manuscript, the emphasis is kept upon the determination of the buckling load for the two-stage pin-mounted telescopic hydraulic cylinder. The buckling governing equation has been derived to obtain the buckling load using an analytical approach. Additionally, the stress condition of cylinder barrels of different stages has been discussed per thick cylinder theory. The finite element analysis has been performed for various dimensions of the hydraulic cylinder. The results obtained from analytical results show close vicinity with the finite element results.