Experimental Analysis of the Slip Phenomenon of Sewage Sludge

2011 ◽  
Vol 243-249 ◽  
pp. 41-44
Author(s):  
Li Zhang ◽  
Min Quan Feng ◽  
Xiao Bin Zhang
Keyword(s):  
Water Content ◽  
Strain Amplitude ◽  
High Speed ◽  
Stress Amplitude ◽  
Wall Slip ◽  
Shearing Flow ◽  
Oscillatory Shear Flow ◽  
Straight Line ◽  
Strain Stress ◽  
Steady Shearing

Wall slip of sweage sludge and affect slip possible factors were studied experimentally by using a rotational rheometer with parallel plate fixtures and by means high speed camera. In the steady shearing flow, the technique involves placing a straight line marker monitoring of wall slip,checking the gap dependence of the stress/ strain data. For sweage sludge of water content 80%, in the shearing flow it was found that, as the strain amplitude increasing, the stress data obtained at different gaps, then, at the certain strain amplitude, started to diverge, indicating that wall slip occurred. But for sweage sludge of water content 90%, these curves are superimpose, indicating no slip occurred. In the dynamic oscillatory shear flow, we analyze the total wave. While strain, stress amplitude decreases with the time, while strain, the stress amplitude remains constant.

Experimental Study on the Impact Factors of Sewage Sludge Wall Slip

2011 ◽  
Vol 422 ◽  
pp. 580-583
Author(s):  
Zhen Xing Li ◽  
Li Zhang ◽  
Ji Zhong Bai
Keyword(s):  
Sewage Sludge ◽  
Water Content ◽  
Strain Amplitude ◽  
High Speed ◽  
Influence Factors ◽  
Wall Slip ◽  
Impact Factors ◽  
Shear Rates ◽  
Time Stress ◽  
The Impact

The influence factors of sewage sludge wall slip were analyzed by using a rotational rheometer with parallel plate fixtures and with high speed camera. The technique involves checking the gap dependence of the stress/strain data and studying the time/stress data trend of strain stepped scanning. For sewage sludge of water content 80%, in the shearing flow it was found that, as the strain amplitude increasing, the stress data obtained at different gaps, then, at certain strain amplitude, started to diverge, indicating that wall slip occurred. But for sewage sludge of water content 87%, these curves are superimpose, indicating no slip occurred. While scanned sewage sludge water content 80% at different shear rates in 5s and 60s, it found that under 5s and 60s respectively, the shear rate is greater than 10s-1 and 0.5s-1 during time/stress curves appeared peak condition, shows slip occurred.

Uniaxial Ratcheting and Low-Cycle Fatigue Failure of U75V Rail Steel

2016 ◽  
Vol 853 ◽  
pp. 246-250 ◽  
Author(s):  
Tao Fang ◽  
Qian Hua Kan ◽  
Guo Zheng Kang ◽  
Wen Yi Yan
Keyword(s):  
Fatigue Life ◽  
Strain Amplitude ◽  
Stress Ratio ◽  
Stress Amplitude ◽  
Rail Steel ◽  
Low Cycle Fatigue ◽  
Mean Stress ◽  
Cycle Fatigue ◽  
Ratcheting Strain ◽  
Cyclic Straining

Experiments on U75V rail steel were carried out to investigate the cyclic feature, ratcheting behavior and low-cycle fatigue under both strain- and stress-controlled loadings at room temperature. It was found that U75V rail steel shows strain amplitude dependent cyclic softening feature, i.e., the responded stress amplitude under strain-controlled decreases with the increasing number of cycles and reaches a stable value after about 20th cycle. Ratcheting strain increases with an increasing stress amplitude and mean stress, except for stress ratio, and the ratcheting strain in failure also increases with an increasing stress amplitude, mean stress and stress ratio. The low-cycle fatigue lives under cyclic straining decrease linearly with an increasing strain amplitude, the fatigue lives under cyclic stressing decrease with an increasing mean stress except for zero mean stress, and decrease with an increasing stress amplitude. Ratcheting behavior with a high mean stress reduces fatigue life of rail steel by comparing fatigue lives under stress cycling with those under strain cycling. Research findings are helpful to evaluate fatigue life of U75V rail steel in the railways with passenger and freight traffic.

scholarly journals A New Rotor Position Measurement Method for Permanent Magnet Spherical Motors

2018 ◽  
Vol 8 (12) ◽  
pp. 2415 ◽  
Author(s):  
Yin Lu ◽  
Cungang Hu ◽  
Qunjing Wang ◽  
Yi Hong ◽  
Weixiang Shen ◽  
...  
Keyword(s):  
Permanent Magnet ◽  
High Speed ◽  
Measurement Method ◽  
Coordinate Frame ◽  
Feature Points ◽  
Position Measurement ◽  
Experimental Platform ◽  
Rotor Position ◽  
Straight Line ◽  
The World

This paper proposes a new high-precision rotor position measurement (RPM) method for permanent magnet spherical motors (PMSMs). In the proposed method, a LED light spot generation module (LSGM) was installed at the top of the rotor shaft. In the LSGM, three LEDs were arranged in a straight line with different distances between them, which were formed as three optical feature points (OFPs). The images of the three OFPs acquired by a high-speed camera were used to calculate the rotor position of PMSMs in the world coordinate frame. An experimental platform was built to verify the effectiveness of the proposed RPM method.

scholarly journals Three-Dimensional (3-D) Immersed-Boundary (IB) Based Tornado Model for Computational Analysis of Disastrous Wind Load on Buildings

2021 ◽  
Author(s):  
Xixiong Guo ◽  
Jun Cao
Keyword(s):  
Wind Field ◽  
High Speed ◽  
Outer Boundary ◽  
Three Dimensional ◽  
Influence Factors ◽  
Research Direction ◽  
Wind Loading ◽  
Immersed Boundary ◽  
Design Strategies ◽  
Straight Line

This study is aimed at developing a novel computational framework that can essentially simulate a tornadic wind field and investigate the wind loadings on ground constructions. It is well known that tornado is a highly turbulent airflow that simultaneously translates, rotates and updrafts with a high speed. Tornadoes induce a significantly elevated level of wind forces if compared to a straight-line wind. A suitably designed building for a straight-line wind would fail to survive when exposed to a tornadic-like wind of the same wind speed. It is necessary to design buildings that are more resistant to tornadoes. Since the study of tornado dynamics relying on field observations and laboratory experiments is usually expensive, restrictive, and time-consuming, computer simulation mainly via the large eddy simulation (LES) method has become a more attractive research direction in shedding light on the intricate characteristics of a tornadic wind field. For numerical simulation of a tornado-building interaction scenario, it looks quite challenging to seek a set of physically-rational and meanwhile computationally-practical boundary conditions to accompany traditional CFD approaches; however, little literature can be found, as of today, in three-dimensional (3D) computational tornado dynamics study. Inspired by the development of the immersed boundary (IB) method, this study employed a re-tailored Rankine-combined vortex model (RCVM) that applies the “relative motion” principle to the translational component of tornado, such that the building is viewed as “virtually” translating towards a “pinned” rotational flow that remains time-invariant at the far field region. This revision renders a steady-state kinematic condition applicable to the outer boundary of a large tornado simulation domain, successfully circumventing the boundary condition updating process that the original RCVM would have to suffer, and tremendously accelerating the computation. Wind loading and its influence factors are comprehensively investigated and analyzed both on a single building and on a multiple-building configuration. The relation between the wind loadings and the height and shape of the building is also examined in detail. Knowledge of these loadings may lead to design strategies that can enable ground construction to be more resistant to tornadoes, reducing the losses caused by this type of disastrous weather.

scholarly journals The human sperm beats anisotropically and asymmetrically in 3D

2019 ◽  
Author(s):  
Hermes Gadêlha ◽  
Paul Hernández-Herrera ◽  
Fernando Montoya ◽  
Alberto Darszon ◽  
Gabriel Corkidi
Keyword(s):  
Ion Channels ◽  
Mathematical Analysis ◽  
Molecular Motors ◽  
High Speed ◽  
3D Imaging ◽  
Human Sperm ◽  
Travelling Wave ◽  
Fundamental Question ◽  
Sperm Flagellum ◽  
Straight Line

The canonical beating of the human sperm flagellum is postulated to be symmetric. This is despite the reported asymmetries inherent to the flagellar axonemal structure, from distribution and activation of molecular motors to, even, the localisation of regulatory ion channels. This raises a fundamental question: how symmetric beating is possible within such intrinsically asymmetric flagellar complex? Here, we employ high-speed 3D imaging with mathematical analysis capable of resolving the flagellar movement in 4D (3D+time). This reveals that the human sperm beating is both anisotropic and asymmetric, and composed by a superposition of two transversal waves: an asymmetric travelling wave and a symmetric standing wave. This novel anisotropic travelling-pulsation mechanism induces sperm rolling self-organisation and causes a flagellar kinematic illusion, so that the beat appears to be symmetric if observed with 2D microscopy. The 3D beating anisotropy thus regularises the intrinsic flagellar asymmetry to achieve symmetric side-to-side movement and straight-line swimming.

scholarly journals Cyclic Deformation Behavior of A Heat-Treated Die-Cast Al-Mg-Si-Based Aluminum Alloy

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4115
Author(s):  
Sohail Mohammed ◽  
Shubham Gupta ◽  
Dejiang Li ◽  
Xiaoqin Zeng ◽  
Daolun Chen
Keyword(s):  
Heat Treatment ◽  
Strain Amplitude ◽  
Cyclic Deformation ◽  
Stress Amplitude ◽  
Cyclic Hardening ◽  
Life Cycles ◽  
Total Strain ◽  
Total Strain Amplitude ◽  
Heat Treated ◽  
Die Cast

The purpose of this investigation was to study the low-cycle fatigue (LCF) behavior of a newly developed high-pressure die-cast (HPDC) Al-5.5Mg-2.5Si-0.6Mn-0.2Fe (AlMgSiMnFe) alloy. The effect of heat-treatment in comparison with its as-cast counterpart was also identified. The layered (α-Al + Mg2Si) eutectic structure plus a small amount of Al8(Fe,Mn)2Si phase in the as-cast condition became an in-situ Mg2Si particulate-reinforced aluminum composite with spherical Mg2Si particles uniformly distributed in the α-Al matrix after heat treatment. Due to the spheroidization of intermetallic phases including both Mg2Si and Al8(Fe,Mn)2Si, the ductility and hardening capacity increased while the yield stress (YS) and ultimate tensile strength (UTS) decreased. Portevin–Le Chatelier effect (or serrated flow) was observed in both tensile stress–strain curves and initial hysteresis loops during cyclic deformation because of dynamic strain aging caused by strong dislocation–precipitate interactions. The alloy exhibited cyclic hardening in both as-cast and heat-treated conditions when the applied total strain amplitude was above 0.4%, below which cyclic stabilization was sustained. The heat-treated alloy displayed a larger plastic strain amplitude and a lower stress amplitude at a given total strain amplitude, demonstrating a superior fatigue resistance in the LCF regime. A simple equation based on the stress amplitude of the first and mid-life cycles ((Δσ/2)first, (Δσ/2)mid) was proposed to characterize the degree of cyclic hardening/softening (D): D=±(Δσ/2)mid − (Δσ/2)first(Δσ/2)first, where the positive sign “+” represents cyclic hardening and the negative sign “−“ reflects cyclic softening.

scholarly journals Thermomechanical Fatigue Behavior of Spray-Deposited SiCp/Al-Si Composite Applied in the High-Speed Railway Brake Disc

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Wei Li ◽  
Huitao Chen ◽  
Lu Zuo ◽  
Jian Chen ◽  
Dongliang Xu ◽  
...  
Keyword(s):  
High Speed ◽  
Stress Amplitude ◽  
Fatigue Behavior ◽  
Phase Interface ◽  
Thermomechanical Fatigue ◽  
Brake Disc ◽  
Dislocation Generation ◽  
Si Content ◽  
Al Matrix ◽  
Sic Particle

The thermomechanical fatigue (TMF) behaviors of spray-deposited SiCp-reinforced Al-Si alloy were investigated in terms of the size of Si particles and the Si content. Thermomechanical fatigue experiments were conducted in the temperature range of 150-400°C. The cyclic response behavior indicated that the continuous cyclic softening was exhibited for all materials, and the increase in SiC particles size and Si content aggravated the softening degree, which was attributed to dislocation generation due to differential thermal contraction at the Al matrix/Si phase interface or Al matrix/SiC particle interface. Meanwhile, the TMF life and stress amplitude of SiCp/Al-7Si composites were greater than those of Al-7Si alloy, and increased with the increasing SiC particle size, which was associated with “load sharing” of the direct strengthening mechanism. The stress amplitude of 4.5μmSiCp/Al-Si composite increased as the Si content increased; however, the influence of Si content on the TMF life was not so significant. The TMF failure mechanism revealed that the crack mainly initiated at the agglomeration of small-particulate SiC and the breakage of large-particulate SiC, and the broken primary Si and the exfoliated eutectic Si accelerated the crack propagation.

scholarly journals Uniform Distribution and Densification of Jets in Needleless Electrospinning Using Annular Tip Nozzle

Polymers ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1301 ◽  
Author(s):  
Hongbo Chen ◽  
Chuansheng Wang ◽  
Imdad Ali ◽  
Haoyi Li ◽  
Xiaoqing Chen ◽  
...  
Keyword(s):  
Free Surface ◽  
High Speed ◽  
Repulsive Force ◽  
Closed Curve ◽  
Environmental Friendliness ◽  
Ultrafine Fibers ◽  
Needleless Electrospinning ◽  
Straight Line ◽  
Distribution Process ◽  
Practical Guidance

Numerous jets can be generated simultaneously on a nozzle by needleless melt electrospinning technology which has the advantages of solvent-free residues and environmental friendliness; and potential industrial application prospects. In this paper, the linear annular tip nozzle was taken as the research object, and the high-speed image acquisition of the jets generation and distribution process of annular tip nozzle was carried out and compared with that of straight-line tip nozzle. The results showed that the repulsive force between the jets caused a slight adjustment in the position of the jets on the free surface, the force between the jets on the annular closed curve canceled each other and eventually reached the equilibrium state, making the position of the jets stable and the distance between the jets the same, and the distance between the jets was related to the intensity of the induced electric field at the tip of the nozzle. Relevant conclusions can provide scientific and practical guidance for the design of needleless electrospinning nozzles on free surface in order to achieve uniform and efficient preparation of ultrafine fibers.

scholarly journals Grip and limb force limits to turning performance in competition horses

2010 ◽  
Vol 278 (1715) ◽  
pp. 2105-2111 ◽  
Author(s):  
Huiling Tan ◽  
Alan M. Wilson
Keyword(s):  
Angular Velocity ◽  
High Speed ◽  
Small Radius ◽  
Maximum Speed ◽  
Large Radius ◽  
Centripetal Acceleration ◽  
Straight Line ◽  
Prey Interaction ◽  
The Coefficient Of Friction ◽  
Stride Parameters

Manoeuverability is a key requirement for successful terrestrial locomotion, especially on variable terrain, and is a deciding factor in predator–prey interaction. Compared with straight-line running, bend running requires additional leg force to generate centripetal acceleration. In humans, this results in a reduction in maximum speed during bend running and a published model assuming maximum limb force as a constraint accurately predicts how much a sprinter must slow down on a bend given his maximum straight-line speed. In contrast, greyhounds do not slow down or change stride parameters during bend running, which suggests that their limbs can apply the additional force for this manoeuvre. We collected horizontal speed and angular velocity of heading of horses while they turned in different scenarios during competitive polo and horse racing. The data were used to evaluate the limits of turning performance. During high-speed turns of large radius horizontal speed was lower on the bend, as would be predicted from a model assuming a limb force limit to running speed. During small radius turns the angular velocity of heading decreased with increasing speed in a manner consistent with the coefficient of friction of the hoof–surface interaction setting the limit to centripetal force to avoid slipping.

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