Exit End Research Articles

Numerical Modeling of the Dispersion Characteristics of Pollutants in the Confluence Area of an Asymmetrical River

It is challenging to investigate the transport and dispersion of contaminants in river confluence areas due to the complex flow dynamics. In recent studies on the flow dynamics in river confluence areas, it has been revealed that changes in inflow conditions (discharge ratio, width-depth ratio and concentration difference) can greatly influence pollutant diffusion. In this study, an asymmetric confluence-type river is modeled by a three-dimensional hydrodynamic water quality model, and three hydrodynamic scenarios are numerically simulated. The results show that a higher discharge ratio and width-depth ratio led to an increase in the lateral diffusion area of pollutants, deviation in the trajectory line of the mixing interface towards the opposite bank of the interchange, and an increase in the mixing rate of pollutants. For R = 0.267 and b/h = 3.75, the pollutants at the bottom are completely mixed in the exit end section. However, the difference in the pollutant concentration slightly affects the area, length and shape of the pollutant dispersion zone and notably affects only the concentration in each section.

FINITE ELEMENT METHOD OF SEEPAGE AND STABILITY ANALYSIS OF SAURA-KEFFI EARTH DAM

Finite element method (FEM) based analysis using the SEEP/W and SLOPE/W sub-programme options of a GEOSTUDIO software was used to analyze Saura-Keffi earth dam in Nasarawa State, Nigeria with the view to analyze the dam seepage and its stability. The created dam geometry was assigned material properties and boundary conditions at reservoir water levels of: minimum (3 m), normal (6 m) and maximum (7 m). The analysis was conducted under the cases that the dam was without and with seepage measures (SCM). The results of the analyzed semi-permeable homogenous dam revealed a percentage reduction inseepage flux to 28.3% when the dam was considered with a central core and complete cut-off trench along the dam crest axis. see figure 7. The pore-water (PWP) revealed a decrease in value from (12 to 11.2) kPa at minimum water head with SCM. The PWP further increased by 18.9% as water rises from 6 m to 7m with SCM. The exit gradient showed an insignificant increase in value of 1.2% with the construction of SCM which indicates less flow at the exit end of the dam leading to increase in stability. The horizontal filter drain at the downstream lower and kept the phreatic line within the dam body to allow for adequate embankment and foundation drainage as shown in figure (5&6). The F.S at the maximum water level revealed an increase in value from 1.27 to 1.52 when a horizontal filter was considered. The Morgenstern-priced method of slope stability was used to estimate an acceptable minimum F.S of 1.52 at 0.5 lambda value with the introduction of horizontal filter.

The evolution of hot spot and nanojet by engineering the local modes of microcylinder

Hot spot and photonic nanojet (PNJ) are subwavelength focused beams generated from the microsphere or microcylinder. In this paper, we proposed a method of excitation of high-order resonant modes in microcylinder with a high-refractive index cladding and modulation of local modes at the exit end to generate the hot spot. A hot spot with a full width at half maximum waist of 66.70nm(λ/8.47) on the surface is obtained and explained by the wave superposition theory modulated by local modes. The influence of local structures and refractive index on the waist, effective length and exit direction of the hot spot is discussed. The focal position of the hot spot can be gradually moved out and converted to the nanojet by engineering the local modes of the microcylinder. Also, a cubic array chip is suggested for decreasing the difficulty of manufacture. And it shows that number and position of the hot spot can be controlled by adjusting the refractive index and height of the local structure. This work provides a possibility for potential applications in the fields of high-throughput super-resolution near-field imaging, localized excitation and imaging of single-molecule fluorescence.

Determination of Separation Performance in CFD-DEM Simulation Using Straw Particles in A Standard Cyclone

Although flow in biological materials sometimes behaves like a continuous one, it cannot be simulated with continuity-based modeling when it comes to discontinuous flow behavior. The Discrete Element Method (DEM) in combination with Computational Fluid Dynamics (CFD) is a computational method for modeling particles in fluid flow by tracking their motion. DEM is widely used in the field of engineering, and its use in the agricultural field is increasing. This study analyzes the CFD-DEM relationship of biological material in aerodynamic systems and reviews current applications. In the article, the definition of aerodynamic systems as a basic principle, particle-fluid and particle-particle interaction forces in the system, modeling of particle motions, CFD-DEM coupling method, and analysis applications of agricultural aerodynamic systems are examined. In this study, simulation experiments were carried out at 100 g/s and 200 g/s straw feeding values at each value of 18-15-12-10-8-6-4 m/s air and straw inlet velocities. The flow near the cyclone walls caused the straw particles to be directed towards the lower exit end of the cyclone. At feed densities of 100 g/s and 200 g/s, the least particle output was obtained at a rate of 18 m/s. The highest cyclone output efficiency was obtained at feed densities of 100 g/s and 200 g/s at a velocity of 12 m/s. The compatibility of the trial simulation results with the literature showed that the CFD-DEM application is an important approach to study the behavior of particulate matter in fluids.

The effect of gas-density gradient on high-harmonic generation from neon-filled cells using annular and Gaussian laser beams

An experimental study was performed to explore the effect of gas-density gradient in laser propagation direction on high-harmonic generation from neon-filled cells using a 50 fs annular and Gaussian Ti:sapphire laser beam. It was observed that, despite 20% lower power, the photon flux of the high-harmonics generated using an annular beam under optimum parameter conditions (∼2.5 × 1010 photons/sec for the 37th order in a 5 mm long cell) is on par with the maximum photon flux generated using a full Gaussian beam (∼2 × 1010 photons/sec for the 37th order in a 15 mm long cell). To elucidate the underlying mechanism for the experimental observation, a numerical simulation of the propagation of both the annular and Gaussian laser beams inside the cell was performed. The simulation was extended to estimate the high-harmonic intensity, after incorporating the effect of laser defocusing, the electron trajectory resolved phase-matching, and gas-density gradient. The dominant role of short electron trajectories was observed in the case of the annular beam, whereas, in the case of the Gaussian beam, a contribution of both short and long trajectories was found. Our analysis shows that, in neon-filled cells, the gas-density gradient present at the laser exit end of the cell plays a dominant role in achieving a high photon flux using an annular laser beam. Further, the annular beam not only provides a higher flux but also has lower divergence and higher coherence. This study will be useful in attosecond pulse metrology as well as in imaging applications viz coherent diffractive imaging.

Solid state infiltration of porous steel with aluminium by the forcefill process

Abstract We report first results on producing a metal – metal composite by forcing solid aluminium to fill a porous steel preform. This process is akin to forcefill used for filling of vias when producing metallic interconnects in microelectronics. Using scanning electron microscopy with energy-dispersive X-ray spectroscopy, it was shown that for nominal pore size as small as 100 μm, the pores could be filled with aluminium throughout the entire preform used, thus demonstrating the viability of the process. An interesting aspect of this solid state ‘infiltration’ is that the tortuous random paths taken by the plastically flowing Al involve numerous kinks. Some of them may induce large localised shear deformation similar to that produced by equal channel angular pressing, which is used to fabricate bulk ultra-fine-grained materials. It is, therefore, conjectured that towards the exit end of the channels the infiltrating material may develop an ultra-fine grain structure and exhibit enhanced strength. It is suggested that the process described can be used to produce metal– metal (or ceramic – metal) composites with unusual mechanical properties. Thin fibres of the material that has percolated through the porous preform can be expected to have a sub-micron grain structure and to possess improved mechanical properties.

Dual-functional underliquid superhydrophobic and superoleophobic stainless steel mesh decorated with Ni3S2 nanorods for continuous oil/water separation

Frequent oil leakages and ever-increasing oily sewage have brought about serious damage to the ecological balance and human health. Therefore, effective and durable separation strategies and use of effective materials are highly desirable. In this work, a superwetting Ni3S2 coating was fabricated on stainless steel mesh (SSM) to achieve continuous oil/water separation. This mesh was superoleophilic in air but superhydrophobic and superoleophobic under oil and water. Once immersed in a liquid, oil/water droplets displayed large contact angles and lower adhesion. A bidirectional T-tube device integrated with two meshes at the two exit ends with inverse wettability was employed to separate oil/water mixtures. This system displayed high separation efficiencies and flux regardless of the oil density, and the separation efficiency was largely maintained after 100 cycles of separation. The same device could also separate immiscible organic solvents. Moreover, the Ni3S2@SSM showed photocatalysis to degrade water-soluble dyes targeting to further relief the water pollution. This multi-superwetting Ni3S2@SSM is expected to be a promising material for practical oil/water separation.

Characterization of micro hole on super alloy GH4037 and stainless steel 304 by millisecond-pulsed Nd:YAG laser processing

In this study, both super alloy GH4037 and stainless steel 304 were selected as experimental materials to be processed by LASERTEC 80 PowerDrill three-dimensional solid laser machining center. The structure of the micro hole was researched by 3D Laser Scanning Confocal Microscope and Scanning Electron Microscope (SEM). Meanwhile, The holes taper, entrance and exit ends diameter, microcrack, recast layer, orifice deposits and the heat affected zone (HAZ) were also investigated. The single factor experimental method was used to research the influences of defocusing amount, pulse energy, repetition frequency, and pulse duration on quality of micro holes. Experimental results indicated that the holes entrance and exit ends diameter enlarged with increased pulse energy from 3.4 J to 4.2 J. The entrance and exit ends diameter of holes decreased with increased pulse duration from 0.5 ms to 2.5 ms. Besides, the variation of holes diameter and taper were more obvious with repetition frequency changing from 10 Hz to 30 Hz, and variation range for the entrance and exit ends diameters and taper were not obvious with increased defocusing amount from −2 mm to 2 mm. The herein results indicated that pulse energy was one of the most significant influencing elements, and higher pulse energy could bring about lower hole taper within a certain range. Meanwhile, shorter pulse duration reduced splash and debris of holes surface. The recast layer, micro crack and HAZ were existed in the both kinds of experimental materials. Moreover, the microcrack and recast layer on holes wall of GH4037 were less than those of 304, and the HAZ in drilling hole for GH4037 was more than that of 304. The experimental results for the holes size were compared with corresponding simulation results under different defocusing amount respectively, which verified the accuracy of simulation results. Combining the above factors, the quality of micro holes drilling on super alloy GH4037 was better than stainless steel 304.

Effect of lead angle of hole expansion mandrel on surface integrity and fatigue performance of TC17 titanium alloy hole structure

For the TC17 titanium alloy, the influence of the leading end angle of the mandrel on the expansion strengthening effect of the hole structure was studied, the surface integrity of the hole expansion strengthened under different process parameters was characterized, the high temperature and low cycle of the original and strengthened samples were tested. Fatigue life and the morphological characteristics of fatigue fracture are analyzed. The results show that the lead angle of the mandrel has a significant effect on the surface roughness after expansion. The uneven plastic flow of the metal on the surface of the hole wall during the expansion process leads to uneven residual stress distribution on the hole wall after expansion, and the residual stress amplitude at the exit end of the expansion is the largest, and the hole wall has a certain depth of residual compressive stress gradient field after expansion. When the interference of the core rod is constant, the fatigue life increases with the increase of the rear lead end angle of the mandrel. When the rear lead end angle is 8°, the median fatigue life gain after strengthening can reach 1.74 times, and the strengthening effect is the best, its minimum cycle life is 16331 times, which is higher than the longest cycle life of the original sample (13965 cycles). After strengthening, the origin of the cracks is changed from the multi-source type in the middle of the hole wall to the single-source crack initiation at the inlet end of the expansion.

Determination of the preferred two different coccinellid species on different aphid species feeding on broad bean plants

In this study, the orientation of two different predator species [(Coccinella septempunctata L., Hippodamia variegata (Goeze) (Coleoptera: Coccinellidae)) to two different aphids [Aphis fabae Scopoli and Acyrthosiphon pisum Harris (Hemiptera: Aphididae)] was investigated. Y-type olfactometer which was made of glass material with one entrance and two exit openings was used in the study. Different applications were applied to the exit ends of the olfactometer and the orientation of the predators dropped from the entrance end was examined. Individuals passing the marked area (10 cm) on the olfactometer were considered to have turned to that plant. All of the trials were conducted separately for each predator and prey with 10 replications. The counts of the insects advancing on the arms of the olfactometer were made 1, 4 and 8 hours after the release. When looking at the data obtained in the first stage of the study, it was determined that the predator insects mostly gravitate towards the leaves infected with aphids; In the second stage, it was observed that C. septempunctata individuals mostly turned towards the side that was contaminated with A. pisum, and H. variegata individuals mostly turned towards the side that was contaminated with A.fabae. When looking at the data obtained from the study, it was determined that the plants damaged by herbivorous insects show an attractive feature for predators. Accordingly, it was concluded that chemicals obtained from broad bean plants damaged by aphids should be analyzed.

Transmissions of photonic topological modes through channels with different shapes

We study the transmission behavior of photonic topological mode through topological microwave channels with different shapes in a two-dimensional photonic crystal platform by the COMSOL Multiphysics software. A four-source-array is set to excite the topological modes. We find that topological modes with up and down pseudospin both can be excited in one channel although they have different intensity. Different channel can provide different transmission ratio between two opposite directions (rightward and leftward). These results suggest the topological mode might undergo a spin-flip process at the exit end face or the sharp bending position of the topological channel.

An Experimental Investigation of a Low Speed Long Linear Induction Motor Divided into Several Stators Connected in Series.(Dept.E)

An experimented study of a linear induction motor whose stator is divided into short stators that are connected in series is presented. The investigation includes a comparison of this motor with another motor having undivided stator. The present investigation is concerned with no-load and full-load conditions. the thrust, the power factor and the efficiency are reported under both constant current and voltage operation measurements of air gab flux over the length of the long stator :md the three short divided stators are also presented. The cascade connection of three divided short stators for different distribution of phase m.m.f. namely the same polarity distribution (N-S-N-S-N-S) and opposite polarity distribution is presented. The experimental results recommended the cascade connection with the same distribution m.m.f. and a minimum distance between'' the stators to yield free movement and reduce the entry and exit ends power loss. The experimental study aims to demonstrate the divided short stator and to solve the problem regarding the suspension of long stator on the train to cope with sleep slope and irregularities of the track.

High‐Fidelity Image Reconstruction through Multimode Fiber via Polarization‐Enhanced Parametric Speckle Imaging

AbstractHigh‐quality signal transmission and imaging through a multimode fiber is essential for optical communications and medical endoscopic imaging, as it can provide high fidelity of the transferred information. Multiple mode superposition and mode coupling distort the incident wave, and a speckle pattern formed at the exit end of a multimode fiber makes the reconstruction of the original object challenging. The transmission matrix method is proposed to characterize the complex mesoscopic optical transmission channels, allowing light to traverse through the random medium. Here, a novel approach, namely polarization‐enhanced parametric speckle imaging, is proposed to improve imaging quality through a multimode fiber by utilizing the properties of polarization evolution through a multimode fiber. The demonstrated superior performance of polarization‐enhanced parametric speckle imaging opens novel avenues for optical communication system and photonics‐based endoscopic diagnosis.

Execution of Safe Blasting Under Adverse Conditions of a Powerhouse Complex: A Revisit to Sardar Sarovar Project, India

When the excavation of the underground powerhouse of the Sardar Sarovar Project, India was nearly complete, cracks were observed on the upstream and downstream walls of the powerhouse, and the installed instrumentation readings sounded an alert for the instability of the powerhouse cavern that could possibly derail the project, further excavation in the powerhouse cavern was halted. After completing stabilisation measures, the remaining underground excavations by drill and blast method were to be completed. This paper revisits case studies of controlled blasting for the remaining excavations, namely a construction ramp, turbine pits, draft tube tunnels connecting the powerhouse, and the concrete plugs erected at the exit ends of the draft tube tunnels. To ensure overall stability around the excavations, blast vibration was controlled by planning the excavations in proper sequences. The damage outside the planned line of excavations was controlled by adopting modified line drilling/smooth blasting techniques. The details of the sequence of excavations, drilling and blasting parameters, compiled from previous publications, are presented in this paper. This paper also describes the reasons why concrete plugs were erected in the draft tube tunnels, the details of the concrete plugs, the optimised drilling and blasting procedure for safe removal of the plugs, and the method adopted to quantify the damage.

Polarization Transmission Matrix for Completely Polarization Control of Focal Spots in Speckle Field of Multimode Fiber

The propagation of light transmitting through a scattering medium generates random speckle. Transmission matrix (TM) is introduced to describe this transmission process. In general, only scalar TM is considered. Meanwhile, for a non-polarization maintaining multimode fiber (MMF), depolarization effect is extremely strong. Therefore, the field at the exit end of a MMF is a speckle with random distribution not only in terms of intensity but also polarization. In addition to traditional TM, we propose polarization TM (PTM) to describe the depolarization effect of a MMF. Based on PTM, the speckle pattern formed by a coherent light transmitting through a MMF can be modulated into one focal spot or multiple focal spots with desired polarization.

Performance analysis of ladder-secondary-linear induction motor with two different secondary types using Magnetic Equivalent Circuit

This paper proposes a Magnetic Equivalent Circuit (MEC) method to model the Ladder-Secondary-Linear Induction Machines (LS-LIMs), where the model accuracy can be determined as desired. This method makes it much easier to change parameters of motor include poles and slots number as well as its dimension than the Finite Element Method (FEM). The end-effect phenomenon is considered in the model by two virtual zones with arbitrary length at the both exit and entrance ends of the primary for saturable LS-LIMs. The proposed MEC method also makes it possible to investigate the motor performance under different secondary structures (two types), bars material and their width. Finally, FEM and experimental results are given to evaluate the accuracy of the proposed method, and simulation time is compared with 2D-FEM. In a general overview, modeling the end-effect and saturation phenomena, analyzing the impacts of different secondary structures and bars width on the performance of motor are studied by the suggested MEC method in the present work.

A numerical insight on machining burr formation: A comprehension to optimization approach

An insight into comprehension and optimization of exit burr formation in orthogonal machining case is presented in the work. Formation of exit burr has been simulated using a three dimensional FE based machining model. Variation of “pivot-point” (point of maximum bending stress, appearing at workpiece exit edge) location on workpiece end and its appearance with respect to tool position during cutting process has been correlated with burr formation process. To minimize the burr formation, machining process variables (including speed, feed and tool rake angle) optimization have been realized employing Abaqus®. Burr lengths at exit end along workpiece depth of cut (ap) are quantified and optimum machining parameters generating less burrs for dry machining of AA2024 are identified. Simulated results pertaining to chip and cutting forces are fairly matched with related experimental results in the published literature.

Probe misalignment calibration in fiber point-diffraction interferometer.

The measuring probe integrated with multiple fiber point-diffraction sources can be applied to measure both the three-dimensional coordinates and highly accurate point-diffraction wavefront. The probe determines the achievable measurement accuracy of fiber point-diffraction interferometer (PDI), in which the fiber exit end plane is required to be parallel with the detector plane. The probe misalignment due to fabrication error could introduce significant measurement error. A high-precision method is proposed to calibrate the probe misalignment in fiber PDI, including the central positioning based on phase difference and tilt adjustment based on Zernike polynomials fitting. Both numerical simulation and experiments have been carried out to demonstrate the feasibility and accuracy of the proposed probe misalignment calibration method. The proposed method provides a feasible way to address the processing uncertainty on measuring probe in fiber PDI, and enables high-precision geometry alignment and misalignment calibration in the interferometric testing systems with case of no imaging lens.

Automated Bus Ticketing System

The regular traditional ticketing system originates with ticket papers dispensed by the staff conductor is replaced by the self-service vending machines. This replaced automated ticketing machine reduces the human work and make the ticketing system easier and used by all the people. This ticketing machine helps the people to easily print the ticket in one touch. The microcontroller that controls all the processes such like controlling the coin box and buttoning system, displaying the ticket and printing the ticket. The machine at the entry and exit end is operated with microcontroller. At the entry side the passenger can print the ticket in their own by selecting the starting and ending point then inserting the corresponding amount in the coin box. At the exit side the controller controls the driver control, display unit and the swiping section. The ticket should be swiped to get the door to open. This swiping section at the exit end helps to avoid cheating. This system is additionally provided with the driver control where the driver of that bus has one control. The driver can indicate the current stopping point of the bus where it is in.

Experimental and Numerical Study of Edge Defects When Turning 17vol.% SiCp/2009Al Composites

In this work, a three-dimensional large-deformation thermo-elastic-plastic finite element model for oblique cutting was established to analyze edge defects during the machining of 17vol.% SiCp/2009Al composites. The formation process of edge defects at the workpiece exit during turning was investigated, and the influence of depth of cut, feed rate, and spindle speed on the edge defect sizes at the workpiece exit was explored. The results show that a negative deformation plane began to form as the cutting tool approached the exit end of cut, and the resultant cracks propagated towards the negative shear deformation plane, which led to workpiece edge defects. In addition, the size of edge defects increased with increasing depth of cut and feed rate, while the spindle speed had less influence on the size of edge defects. The numerical results of the effects of cutting parameters on edge defects were also compared to those of the turning experimental data, and were found to be in reasonable agreement.