Dry Cylinders Research Articles

A novel weight index-based uniform partition technique of multi-dimensional probability space for structural uncertainty quantification

Accurately and efficiently achieving the uncertainty quantification of engineering structures is a challenging issue. The direct probability integral method (DPIM) provides an effective pathway to address this issue. However, the key partition technique via Voronoi cell of DPIM requires a prohibitive computational burden for multi-dimensional probability space. Moreover, due to the distributed nonuniformity of representative points, the accuracy of DPIM with the partition technique via Voronoi cell (DPIM-Voronoi) for obtaining the response probability density function (PDF) of structures with multi-dimensional probability space still needs to be improved. To this end, a novel weight index-based uniform partition technique is proposed in this study. This technique can generate uniformly distributed representative points and calculate their assigned probabilities using the weight indexes of representative regions. This feature ensures that the representative points can fill the probability space in a highly uniform manner, and avoid the resource-consuming calculation process of assigned probability by Monte Carlo simulation in the original partition technique via Voronoi cell. Based on the proposed technique, DPIM with a Weight index-based Uniform partition technique (DPIM-WU) is developed. Compared to DPIM-Voronoi, the advantages of DPIM-WU include: (1) improving the computational accuracy of response PDF for structures with multi-dimensional probability space, especially in the tail region, leading to improved accuracy of the dynamic reliability; (2) remarkably reducing the computational cost, with minimal computer memory required for the partition process of multi-dimensional probability space; (3) enhancing the robustness to the number of representative points. These advantages are verified through the stochastic response and dynamic reliability analyses of four typical examples, including the 5-story buildings, dry friction system, cylinder structure, and adjacent buildings with pounding motion. Notably, in the stochastic pounding response analysis of adjacent buildings, a stochastic P-bifurcation occurs as the coefficient of variation of the structural parameters decreases.

Sperm characteristics of cryopreserved Prochilodus lineatus semen after adding cholesterol-loaded cyclodextrin

The experiment evaluated the effect of adding cholesterol-loaded cyclodextrin (CLC) to Prochilodus lineatus fish (Curimata) semen on post-thaw sperm quality. Twelve adult fish were used for sperm collection after induced spermiation with carp pituitary gland. The semen was diluted and treated with CLC in concentrations of 0 (control), 0.5, 1.0, 2.0, 3.0, and 4.0 mg for 120 × 106 spermatozoa/ml, loaded in 0.5 ml straws, packaged and placed in dry vapor vessel cylinders for 24 h before being submerged in liquid nitrogen for storage. The samples were thawed in a water bath at 60 °C for 8 s, and the sperm parameters evaluated were motility, activation duration, longevity, plasma membrane integrity, and morphology. Data were tested for normal distribution and ANOVA, followed by Friedman test (P < 0.05). Spermatozoa treated with CLC displayed higher motility than the control (P < 0.05). The duration of sperm activation was longer in sperm treated with 0.5, 1.0, and 2.0 mg of CLC than in control (P < 0.05). The membrane integrity was higher in sperm treated with 0.5, 1.0, 2.0, and 3.0 mg of CLC than in control and four mg-treated samples (P < 0.05). The sperm longevity and morphology alterations did not differ between treatments (P > 0.05). Adding 0.5, 1.0, or 2.0 mg of CLC in Prochilodus lineatus semen before cryopreservation improves sperm motility and membrane integrity.

Compressive mechanical properties of dry antler cortical bone cylinders from different cervidae species

Antlers are bony structures composed predominantly of primary osteons with unique mechanical properties due to their specific use by deer as weapon and shield. Antler bone fracture resistance has attracted prior scrutiny through experimental tests and theoretical models. To characterize antler mechanical properties, compression of cubes, or bending or tensioning of rectangular bars have been performed in the literature with variations in the protocols precluding comparisons of the data. Compression testing is a widely used experimental technique for determining the mechanical properties of specimens excised from cortical or cancellous regions of bone. However, the recommended geometry for compression tests is the cylinder, being more representative of the real performances of the material. The purpose of research was to report data for compressive strength and stiffness of antler cortical bone following current guidelines. Cylinders (n = 296) of dry antler cortical bone from either the main beam or the tines of Cervus elaphus, Rangifer tarandus, Cervus nippon and Damadama were tested. This study highlights the fact that compression of antler cortical bone cylinders following current guidelines is feasible but not applicable in all species. Standardization of the testing protocols could help to compare data from the literature. This study also confirms that sample localization has no effect on the mechanical properties, that sample density has a significant impact and allows enriching the knowledge of the mechanical properties of dry antler cortical bone.

Research on wet-jet and wet-spun carbon fiber prepreg yarn for dry winding and its properties

Through the transformation of basic equipment, this paper realizes the control of the stable resin content of prepreg yarn while fully maintaining the impregnation. Through the research on the resin curing process, resin content, and aging degree of the resin system during the prepreg manufacturing process, the resin content and aging process of the prepreg corresponding to the optimal tensile performance of the NOL ring were determined, and a high-tension winding method was obtained. The prepreg yarn MP01/HF30F/28 prepreg yarn. During the manufacturing process of wound gas cylinders, through the research on the curing system and layup design, the burst strength of dry wound gas cylinders reached 68.5MPa, and the corresponding fiber performance conversion rate was 81.2%, which exceeded that of wet-sprayed wet-spun fibers. The blasting performance conversion rate of wound gas cylinders is 19.8%. Thus opening up a new application method of wet-jet wet-spun carbon fiber in the field of winding.

Numerical observation and analytical formulation of droplet impact and spreading around the thin vertical cylinder

The dynamic characteristics of a water droplet impact on a thin vertical dry solid cylinder are delineated numerically. Finite volume-based axisymmetric simulations are carried out by employing the volume-of-fluid method to predict complex hydrodynamic behaviors. To simulate the present computational work, the conservation equations of mass, momentum, and volume fraction are solved. The droplet surface undergoes a continuous deformation during impact to the thin cylindrical target by resulting in various crucial stages: free fall, hitting, cap formation, encapsulation, uncovering, and detachment. The range of cylinder-to-droplet diameter ratio (Dc/Do) is considered to be from 0.13 to 0.4 for the present computational study to observe different deformation patterns of the droplet. The influence of contact angle (θ), Dc/Do, We, Oh, and Bo on the maximum deformation factor is elucidated from the numerical results. The findings show that the maximum deformation factor increases with the increasing We and the reducing contact angle. An analytical model has been formulated to elucidate the maximum deformation factor, which shows an excellent agreement with the numerical results. Furthermore, a correlation was developed to predict maximum deformation factors in terms of θ, Dc/Do, We, and Oh, which operates exceptionally well within ±1% of the computational data.

Experimenting with Odour Proficiency Tests Implementation Using Synthetic Bench Loops

Uncertainty in the quantification of odour measurements is a difficult (but needed) task. Critical aspects include panel selection (required by dynamic olfactometry), sampling, and stability of the samples. Proficiency tests (PTs) can help evaluate such contributions; however, the classical approach to PTs, in which laboratories analyse real samples taken from the field, are not as applicable in this field, and are often implemented by only using dry gas cylinders containing stable compounds. Consequently, uncertainties related to the sampling activity cannot be assessed. In particular, high odour levels and the presence of water vapour in emission sources can create significative biases due to sampling techniques used and chemical reactions that can occur before analysis. In this work, we present experimental notes, developed using the experimental facility ‘LOOP’, realised at the RSE research centre in Italy, in order to “help” the definition, in an upgraded protocol for implementing PTs for odour determinations. Using this bench loop is advantageous as it involves the possibility of implementing samples in conditions very similar to reality (i.e., high temperatures, high water content, and the presence of chemical interferents).

Investigation of thermal conductivity of orange and tangerine juices in non-stationary state

Thermal conductivity is one of the main thermophysical properties of liquid food products, including fruit and vegetable juices. Known experimental installations measure the thermal conductivity of stationary liquids. This results in significant deviations from the actual numbers. A method of determining the thermal conductivity of a fluid in motion and an experimental installation implementing the proposed method are suggested. The developed experimental installation consists of two coaxial cylinders: internal and external. A gap between cylinders is filled with analysed liquid. The object of the study was the juices of subtropical fruits, such as oranges, tangerines grown in the subtropical regions of the Republic of Azerbaijan. In this work, the thermal conductivity of juices was also investigated during forced movement on an installation also consisting of two coaxial cylinders. Experimental measurements of thermal conductivity for orange and mandarin juices were carried out. Experiments were carried out at frequencies from 50, 100, 150 and 200 s-. A general description of the dependence of thermal conductivity on temperature, dry matter concentration and rotational speed made it possible to develop a model, in particular for orange juice. The described method and experimental installation for measuring the thermal conductivity of a liquid in a non-stationary state made it possible to develop a mathematical model describing the dependence of thermal conductivity on temperature, dry matter content and cylinder speed.

Behavioral Deficits in Mice with Postnatal Disruption of Ndel1 in Forebrain Excitatory Neurons: Implications for Epilepsy and Neuropsychiatric Disorders.

Dysfunction of nuclear distribution element-like 1 (Ndel1) is associated with schizophrenia, a neuropsychiatric disorder characterized by cognitive impairment and with seizures as comorbidity. The levels of Ndel1 are also altered in human and models with epilepsy, a chronic condition whose hallmark feature is the occurrence of spontaneous recurrent seizures and is typically associated with comorbid conditions including learning and memory deficits, anxiety, and depression. In this study, we analyzed the behaviors of mice postnatally deficient for Ndel1 in forebrain excitatory neurons (Ndel1 CKO) that exhibit spatial learning and memory deficits, seizures, and shortened lifespan. Ndel1 CKO mice underperformed in species-specific tasks, that is, the nest building, open field, Y maze, forced swim, and dry cylinder tasks. We surveyed the expression and/or activity of a dozen molecules related to Ndel1 functions and found changes that may contribute to the abnormal behaviors. Finally, we tested the impact of Reelin glycoprotein that shows protective effects in the hippocampus of Ndel1 CKO, on the performance of the mutant animals in the nest building task. Our study highlights the importance of Ndel1 in the manifestation of species-specific animal behaviors that may be relevant to our understanding of the clinical conditions shared between neuropsychiatric disorders and epilepsy.

Analysis of out-of-round deformation of a dry cylinder liner of a non-road high-pressure common-rail diesel engine based on multi-field coupling

The deformation of cylinder liner directly affects the sealing performance of the friction components in internal combustion engines, resulting in high oil consumption, engine power loss, and high-particulate matter emissions. Previous research works focused more on deformation of the wet vehicular cylinder liners, however, the effects of different loads on the dry liner deformation is not clear yet. A non-road high-pressure common-rail diesel engine was selected as the research object, and a coupled model of the engine was developed based on fluid–solid coupled heat transfer theory. After the accuracy of the model was verified by temperature measurement of the cylinder head and cylinder liner, deformation of the dry cylinder liner was studied. The results show that the axial and radial deformations of the cylinder liner are not uniform under the bolt preload condition. Large deformation occurs at the first liner and fourth liner, with the maximum deformation occurring at the top of fourth liner for 10.14 μm. Under the condition of thermal load, the temperature of cylinder liner exhibits a distribution of three-segments from the top to bottom. The liner deformation is not uniform, and the maximum deformation occurs at the top of the fourth liner for 304 μm. The radial deformations of all four cylinder liners present a symmetrical structure of a “heart” shape with respect to the centerline of the second and third cylinders. The axial deformation of each liner exhibits a “barrel” shape which is convex in the middle and narrow at the two ends.

Design Optimization and Analysis of Thermoacoustic Refrigerators

Thermoacoustic refrigeration, a novel technology, uses eco-friendly gases like helium, air or the mixture of noble gases as working substances in the absence of moving parts. The design, optimization and analysis of thermoacoustic refrigerators using helium and air as oscillating gases are discussed. Pure helium is chosen since it is proven as the best and economical working gas compared to the alternate pure or the mixture of noble gases. Air is chosen since it is abundant in nature and the least cost of the pressurized dry air cylinders. The design optimization strategies discussed in this paper serve as a guide for aspiring researchers in the design and development of thermoacoustic coolers. Cooling power as a function of stack diameter is discussed. Theoretical results of the optimized coolers are compared with DeltaEC simulation results for validation and are in agreement with each other.

Isothermal drying kinetics of sewage sludge using weathered coal fly ash as adjuvant for agronomic application

ABSTRACT This study aims to evaluate the effect of weathered coal fly ash (CFA) as a drying adjuvant of sewage sludge (SS) to produce a soil amendment. The high amount of SS and CFA creates a complex waste management problem in many countries, requiring more research efforts. Towards a circular economy, CFA can be viewed as an anthropogenic inorganic by-product with valuable nutrients (e.g. K), which can be recovered in combination with SS (rich in organic matter, N, and P). Different temperatures (70, 85, 100, 115, and 130 °C) are tested to dry small SS cylinders, without and with 0.15 g CFA g−1 of SSwet basis (wb). By fitting appropriate models to the experimental drying curves, it is possible to observe an improvement of 1-17% in the diffusion coefficient and 7-19% in the kinetic constants, using CFA. The best drying conditions are achieved with CFA as an adjuvant at 130 °C, where the drying rate is 31.61 gH2O kg−1 SSwb min−1. Phytotoxicity and growth assays are performed to evaluate the effect of the produced materials in the soil. The product with SS and CFA shows the potential to improve soil condition due to (i) the organic matter, N, P, and K content, (ii) the lower phytotoxic effect when compared to raw SS; (iii) the soil pH correction. Thus, not only the addition of weathered CFA facilitates the drying of SS but also the final product has benefits to soil conditions.

Fatigue in Concrete under Low-Cycle Tensile Loading Using a Pressure-Tension Apparatus

Fatigue due to low-cycle tensile loading in plain concrete was examined under different conditions using the pressure-tension apparatus. A total of 22 wet or dry standard concrete cylinders (100 mm × 200 mm) were tested. By definition, low-cycle loading refers to the concept of multiple load cycles applied at high stress levels (i.e., a concrete structure subjected to seismic loading). Results suggest that concrete samples subjected to low-cycle tensile loading will fail after a relatively low number of cycles of loading and at a lower magnitude of stress compared to the maximum value applied during cyclic loading. Furthermore, non-destructive testing was employed in order to ascertain the extent of progressive damage inflicted by tensile loading in concrete specimens. It was found that ultrasonic pulse velocity is a viable technique for evaluating the damage consequential of loads applied to concrete, including that resultant from low levels of tensile stress (i.e., as low as 10% of its maximum tensile capacity). Additionally, finite element analysis was performed on a modeled version of the pressure-tension apparatus with a sample of concrete, which has yielded similar results to the experimental work.

Prediction of NO and NO2 Concentrations in Ozone Injected Diesel Exhaust after NTP Treatment Using Dimensional Analysis

NTP based Ozone injection cascaded with catalysts/adsorbents for diesel exhaust treatment has been demonstrated by various researchers as a competent method for mitigation of nitrogen oxides. In this present study, one more NTP reactor is cascaded instead of catalysts/adsorbents to treat the ozone mixed diesel exhaust. While most of the laboratory studies were carried out using expensive dry air cylinders for ozone generation, in the present study, ozone has been generated from atmospheric air only. The nitrogen oxides removal/conversion efficiency of this process depends on various electrical and physical parameters. A dimensionless relation has been obtained between the ratio of summation of NO and NO2 concentrations after treatment to that before treatment and other parameters affecting nitrogen oxides removal using dimensional analysis. Prediction of sum of NO and NO2 concentrations with the variation in six dominant parameters have been done using nonlinear regression technique. Six parameters, i.e. ozone concentration, voltage, frequency, flow rate, temperature and discharge gap have been varied to collect the experimental data required to train and test this model. The predicted sum of NO and NO2 concentrations are found to be well matching with the experimental results. The RMS error is found to be 3.7 % and 5.9 % respectively for training and test data.

Excitation of the large-amplitude vibrations of a circular cylinder under normal wind conditions in the critical Reynolds number range

The specific flow regime in which the large-amplitude vibrations of dry circular cylinders are observed in the critical Reynolds number range remains unclear because several different flow regimes overlap in this narrow range. The aerodynamic forces on a stationary circular cylinder and the displacement of an elastically mounted cylinder were measured using the same model at same wind speeds corresponding to Reynolds number from 1.2×105 to 4.3×105 to reveal the characteristics of aerodynamic forces and potential vibrations in different regimes. The results show that the large amplitude vibrations of a dry circular cylinder under normal wind conditions can be excited by unsteady reattachment only during a transitional process between flow regimes rather than throughout the entire critical Reynolds number range.

The Effects of pH and Temperature on Compressive Strength of Synthetic Fiber-Reinforced Concrete Cylinders Exposed to Sulfuric Acid

Abstract Synthetic fibers are among the various types of fibers being used to improve the tensile behavior of concrete. They have a competitive edge over other fibers because they are resistant to most chemicals, which increases the durability. Acid attacks are one of the most threatening scenarios, especially for concrete sewer pipes and culverts. In this study, dry cast concrete cylinders, reinforced with two different volume fractions (0.52 % and 1.04 %) of polypropylene fibers, were constructed and immersed for four months in sulfuric acid solutions of two different pH and three different temperatures. The results showed that a fiber volume fraction of 1.04 % reduces the adverse effects of acid on the compressive strength of concrete, and higher temperatures and lower pH lead to extreme deterioration. The results of this study revealed that a pH of 2.5, along with the highest temperature, deteriorated the specimens more than twice as much as a pH of 4.5 at the lowest temperature.

Monitoring the residual strain of concrete in a freezing-thawing environment using white light interferometer

In order to monitor the residual strain of concrete, which is caused by freezing-thawing (F-T) cycles, a fiber optic F-T sensor based on white light interferometer (WLI) technique is proposed, designed, and tested. The single-mode optical fiber is enwound on the middle surface of concrete cylinder as strain gauge, and WLI technique is used as the acquisitive means of data. To study the feasibility of the proposed F-T sensor, a dry concrete cylinder (T-sensor) was fabricated and exposed it in F-T condition without any solution. The result shows that the strain of T-sensor has a good repeatability with F-T cycles. Two types of mixed proportions of concrete were also fabricated to study the changes of residual strain of concrete which subject to F-T cycles and chloride salt attack. The results indicate that the residual strain increases with F-T cycles, which gives a perspective to understand the damage of concrete exposed in F-T cycles and chloride salt attack.

SPH modelling of viscous flow past a circular cylinder interacting with a free surface

Abstract Single-phase two-dimensional flow past a circular cylinder intersecting, or close to, a free surface at a Reynolds number of 180 is numerically investigated in this paper series using the Smoothed Particle Hydrodynamics (SPH) method. The wake behavior for Froude numbers between 0.3 and 2.0, based on the diameter, and for submergence-diameter ratios between − 0.5 and 2.5 is examined. This range significantly extends existing literature on the topic. Vorticity shed by the cylinder, vortex generation due to free-surface breaking, and mixing processes are discussed. Regarding the submergence dependence, it has been found that for small gap ratios, the classical von Karman vortex shedding from the cylinder does not take place. In turn, vortex shedding originates from wave-breaking at the free surface, occurring simultaneously with the transport of free-surface fluid elements into the bulk of the fluid. It has been also found that for even smaller depth ratios, a vorticity layer remains spatially localized between the cylinder and the free surface, and a large stagnation recirculating area develops behind the cylinder. In some of these cases, the whole mass of fluid in that area eventually gets detached after several shedding cycles and it is advected downstream. According to the authors’ knowledge, this is a previously unreported form of wake instability. It has been also found that as the Froude number is increased, the classical von Karman vortex street shed from the cylinder is blocked only to be recovered at very high Froude numbers, in agreement with linear stability predictions. Regarding the challenging and not previously investigated half-submerged configuration, flows in which the cylinder acts as a barrier, flows with alternation of dry and wet cylinder top surface, and flows with cavities have been described.

Autoignition of wood under combined convective and radiative heating

Many wildland fire models assume radiation heat transfer controls fuel particle ignition. However, evidence suggests that radiation is insufficient to ignite the predominantly small, thin fuel particles in wildlands and that convective heating by flame contact is a critical component. Here, convective ignition was studied using an apparatus containing two 6.5kW electrical heaters to heat air from 600°C to 800°C. Steel screens straightened the flow and provided background radiant heat. This apparatus produced autoignition of dry red oak cylinders and disks. Cylinder diameter was varied from 0.64 to 1.91cm and length from 2.5 to 7.5cm. Disk diameters varied from 2.54 to 5.08cm and 1 to 4mm thick. The airflow rate varied slightly from 1.55 to 1.71m/s due to the density difference. A simplified analytical model was developed that predicted the measured times reasonably well for air temperatures of 700°C and above.

Full-scale measurement of wind pressure on the surface of an oscillating circular cylinders

Under wind excitation, many slender structural members with circular cross sections have exhibited large-amplitude vibrations. The nature of some problematic vibrations remains to be fully understood. To investigate the excitation mechanisms that can cause the vibrations, an experimental campaign was conducted to measure simultaneously the wind pressure on the surface of a circular cylinder in the atmospheric boundary layer and the acceleration of this cylinder. The pressure and acceleration measurements were used to investigate the interaction between the cylinder and the turbulent wind in subcritical and critical Reynolds number ranges. The study revealed several effects of turbulence in wind in the atmospheric boundary layer on the critical transition, including the promotion of early critical transition, the attenuation of the single separation bubble, and the early cessation of the coherent vortex shedding. A coherent fluctuating axial flow component in the wake of circular cylinders yawed to the flow, which has been previously observed in wind tunnel tests in smooth flow and postulated to be critical for the onset of dry cylinder vibration at high reduced velocity, was not observed in the present experiment.

Fabrication and Surface Functionalization of Highly Birefringent Particles for Optical Torque Wrench

Conventional optical tweezers are limited by the ability to apply only translational manipulation to probe the diverse biological systems. The recent extension of optical tweezers, i.e., the optical torque wrench (OTW), allows the direct application and measurement of torque. The OTW provides a platform to measure rotational dynamics of biomolecules and motors including the torque-dependence of DNA or DNA-protein interactions, and of powerful machines such as F0F1-ATP-synthase or bacterial flagellar motor.The applicable torque of the OTW is largely dependent on the birefringence of the trapped particle. Quartz (SiO2) is widely used due to its facile fabrication and stability in biological environments. However, the birefringence of quartz is limited to fully investigate the torque-speed relationships of diverse biological systems so we explored more highly birefringent crystals such as rutile (TiO2) and vanadate (YVO4). Developing novel fabrication protocol is required because the particle fabrication from these alternative crystals is not as straightforward as quartz. For example, Cr was used as a mask for dry etching cylinders from rutile with SF6/CH4 processing gases and it resulted in etching selectivity of 1:28 which is higher than electron beam resist mask with selectivity of 1:1.3.To promote the selective attachment of the particle to target biological system, a submicron-sized protrusion can be fabricated on one end of a cylindrical particle and functionalized with specific ligand biomolecules. Alkoxysilane based surface crosslinkers, such as APTES, that are commonly used to bind biomolecules to solid supports, tend to polymerize and result in inhomogeneous surface coatings. To obtain uniform, dense, and reproducible surface coating for nanoscale structures, we explored the use of cyclic aza-silanes as alternative crosslinkers for biomolecule attachment.