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Sparisoma Viridi

Publications and source records attributed to Sparisoma Viridi.

At least 19 recordsLinked to original sources

Second Order Phase Transition and Universality of Self-Buckled Elastic Slender Columns

Self-buckling is an interesting phenomenon that is easily found around us, either in nature or in objects made by human. Palm fronds which initially directed upward when they were short and turned into bending after appreciably longer is an example of the self-buckling phenomenon. We report here that the self-buckling of columns can be treated as a process of second order phase transition by considering the straight column as disorder state, the bending column as order state, and the temperature as the inverse of column length. The critical temperature corresponds to the inverse of critical length for buckling, 1/Lcr, and the deviation angle made by column free end relative to vertical direction satisfies a scaling relationship with a scaling power of 0.485. Changing of the column geometry from the vertically upward to the bending state can be considered as a transition from disorder state to order state.

physics.class-ph↗

Experiment and Modeling of Rice Winnowing: Granular Segregation Method in Ancient Traditions

Rice winnowing is a process of separation of small and large rice grains by air flow practiced since the ancient human history especially in societies where rice is the main source of carbohydrate (in Asia, Africa, and Latin America). Indeed, this process contains rich of scientific rule but has never been documented by the old society. We report here experimental investigation of the rice winnowing and develop a physical model to explain the process of segregation of rice grains having different size or density. Flapping the tray in the winnowing process, generates a vortex centered at position around the tray free end. We demonstrated numerically that the effectiveness of segregation is strongly depended on the different in grain sizes (for grain from the same material), the initial position of the grain, and the angular velocity of the vortex generated by flapping the tray. We obtained a phase diagram describing different final conditions of winnowing process (either the small grains move towards the tray fee end or move toward the inner end of the tray, able or unable to leave the tray at the free end). The result can be useful to design a new method in separating grains based on size or density.

cond-mat.soft↗

Modeling and Characterization of Charged Particle Trajectories in an Oscillating Magnetic Field

A constant magnetic field has frequently been discussed and has been known that it can cause a charged particle to form interesting trajectories such as cycloid and helix in presence of electric field, but a changing magnetic field is rarely discussed. In this work, modeling and characterization of charged particle trajectories in oscillating magnetic field is reported. The modeling is performed using Euler method with speed corrector. The result shows that there are two types of trajectory patterns that will recur for every $180 n T_0$ ($n = 0, 1, 2, ..$) in increasing of magnetic field oscillation period, where $T_0$ is about $6.25\times10^{-7}$ s.

physics.class-ph↗

Growth of Smaller Grain Attached on Larger One: Algorithm to Overcome Unphysical Overlap between Grain

As a smaller grain, which is attached on larger one, is growing, it pushes also the larger one and other grains in its surrounding. In a simulation of similar system, repulsive force such as contact force based on linear spring-dashpot model can not accommodate this situation when cell growing rate is faster than simulation time step, since it produces sudden large overlap between grains that makes unphysical result. An algorithm that preserves system linear momentum by introducing additional velocity induced by cell growth is presented in this work. It should be performed in an implicit step. The algorithm has successfully eliminated unphysical overlap.

cond-mat.soft↗

Studying Brazil-Nut Effect History Line using Disk-Formed Objects, Scanner, and Web Browser

Grains configuration snapshots of Brazil-nut effect (BNE) in two-dimension are physically modeled using disk-formed objects, e.g., buttons and magnetic pin. These BNE configurations are artificially designed to mimic the real ones observed in experiments. A computer scanner is used to capture the configurations. Obtained images are then digitized using web browser running a HTML equipped with a JavaScript code, which is built mainly only for this work. From digitization process all grains positions (granular bed and intruder) are obtained, which is later analyzed using the simplest model, i.e., potential energy. Since the minimum energy principle (MEP) suggests that a closed system should go to its state with minimum internal energy, our BNE system must also obey it. Evolution of only the intruder seems to violate MEP but not for the whole system. Grains compaction plays important role, so that the system can achieve its configuration with minimum potential energy.

cond-mat.soft↗

Energy Conversion in Lifting Mass Vertically using a DC Electric Motor by Observing Required Time to Lift Object for a Certain Height

In lifting mass vertically using a DC electric motor energy conversion from electric energy, through intermediate kinetic energy, to gravitation potential energy shows that time required Δt to lift load mass m for height h is dependent quadratically to m. Several approaches to explain the experiment observation are discussed in this work, from ideal energy conversion to numerical solution from differential equation.

physics.ed-ph↗

Two-dimension tissue growth model based on circular granular cells for cells with small overlap

Tissue growth can be modeled in two dimension by only using circular granular cells, which can grow and produce child. Linear spring-dashpot model is used to bind the cells with a cut-off interaction range of 1.1 times sum of radii of interacted cells. Simulation steps must be divided into explicit and implicit ones due to cell growing stage and cell position rearrangement. This division is aimed to avoid simulation problem. Only in the explicit steps time changes is performed. Large cells overlap is chosen as termination condition of tissue growth. Only some cells configuration can growth to infinite time without encountering the large cells overlap. These configurations, and the other also, are presented in this work. Simulation time $t$ increases as cell number $N$ increases due to raise of interaction number between two cells. Linear and network configurations tend to aligned with different asymtotic function, that relates $N$ and $t$, for large $N$.

physics.bio-ph↗

Lup-Like Cantilever Beam for Small Deflection

A lup-like cantilever beam are discussed in this work. For small deflection it can be approximated as a spring-mass system with certain spring constant whose effective mass is larger than the usual constant rectangular cross section cantilever beam. A new parameter $β$ is introduced to relates some the properties of lup-like cantilever beam to the usual one. Influence of beam witdh $B_0$ and head width $B_t$ to value of $β$ is also presented.

physics.ins-det↗

Measuring Quasi-Static and Kinetic Coefficient of Restitution Simultaneously using Levitation Mass Method: Experiment and Simulation

Observed peaks in a levitation mass method (LMM), which are usually addressed to signal noise, are discussed in this work. This phenomenon arises due to bounce from plate which is collided by moving part in LMM measurement system. Normally, the moving part and the plate stick very good after their first contact. Simulation using molecular dynamics (MD) method is performed to prove the bounce prognosis.

physics.ins-det↗

A Simple Viscometer for High School and First Years Undergraduate Program Students: Theory and Experiment

A simple viscometer consists of mineral water bottle and trink straw is used to predict vicosity of water. A model is derived from Bernoulli's principle and Poiseulli's law. Value about 0.374 - 0.707 cP is obtained for observation in room temperature. About 10 minutes of observation time is needed to get the data. Keywords: equation of continuity, Bernoulli's equation, viscosity coefficient, Poiseulli flow.

physics.pop-ph↗

Application of Computational Physics: Blood Vessel Constrictions and Medical Infuses

Application of computation in many fields are growing fast in last two decades. Increasing on computation performance helps researchers to understand natural phenomena in many fields of science and technology including in life sciences. Computational fluid dynamic is one of numerical methods which is very popular used to describe those phenomena. In this paper we propose moving particle semi-implicit (MPS) and molecular dynamics (MD) to describe different phenomena in blood vessel. The effect of increasing the blood pressure on vessel wall will be calculate using MD methods, while the two fluid blending dynamics will be discussed using MPS. Result from the first phenomenon shows that around 80% of constriction on blood vessel make blood vessel increase and will start to leak on vessel wall, while from the second phenomenon the result shows the visualization of two fluids mixture (drugs and blood) influenced by ratio of drugs debit to blood debit. Keywords: molecular dynamic, blood vessel, fluid dynamic, moving particle semi implicit.

physics.bio-ph↗

Molecular Dynamics Simulation of Soft Grains: Malaria-Infected Red Blood Cells Motion within Obstructed 2-D Capillary Vessel

Molecular dynamics has been widely used to numerically solve equation of motion of classical many-particle system. It can be used to simulate many systems including biophysics, whose complexity level is determined by the involved elements. Based on this method, a numerical model had been constructed to mimic the behaviour of malaria-infected red blood cells within capillary vessel. The model was governed by three forces namely Coulomb force, normal force, and Stokes force. By utilizing two dimensional four-cells scheme, theoretical observation was carried out to test its capability. Although the parameters were chosen deliberately, all of the quantities were given arbitrary value. Despite this fact, the results were quite satisfactory. Combined with the previous results, it can be said that the proposed model were sufficient enough to mimic the malaria-infected red blood cells motion within obstructed capillary vessel. Keywords: molecular dynamics, two-dimensional model, red-blood cell motion, malaria

physics.bio-ph↗

Study Of Internal Response Of Epoxy Due To Compressive Load Via Experiment And Simulation Using Abaqus FEA Software

Epoxy is widely used primarily as a matrix material in the manufacture of polymer matrix composite. Epoxy behavior under compression load has to be understood before the mechanical behavior of polymer matrix composite can be accurately predicted. Simulation model combined with experiment and image analysis have been used to investigate internal response of epoxy polymeric materials subjected to compressive loads. In the experiment, small carbon-based material rods are inserted in the epoxy. The samples are held in one side and subjected to compressive load on the other side. All the samples swell at load sides. Image analysis on the carbon-based rods figures out the internal response, which seems to be isotropy in lateral direction. The results are compared to simulation results. The simulation is conducted using Abaqus FEA software. Similar condition is obtained when a brittle thin material is stuck to the top of simulation model. Keywords: Abaqus FEA, compression, epoxy, polymer matrix composites

cond-mat.mtrl-sci↗

Automatic Road Lighting System (ARLS) Model Based on Image Processing of Moving Object

Using a vehicle toy (in next future called vehicle) as a moving object an automatic road lighting system (ARLS) model is constructed. A digital video camera with 25 fps is used to capture the vehicle motion as it moves in the test segment of the road. Captured images are then processed to calculate vehicle speed. This information of the speed together with position of vehicle is then used to control the lighting system along the path that passes by the vehicle. Length of the road test segment is 1 m, the video camera is positioned about 1.1 m above the test segment, and the vehicle toy dimension is 13 cm \times 9.3 cm. In this model, the maximum speed that ARLS can handle is about 1.32 m/s, and the highest performance is obtained about 91% at speed 0.93 m/s.

cs.CV↗

Study on Antibody-Virus Interaction using Molecular Dynamics: Two Dimensional Simulation on Immunoglobulin Reaction against Human Papillomavirus

Human Papillomavirus (HPV) has been known as one of the cause of virus-induced cancer such as cervical cancer and carcinoma. Among other types of cancer, this type has higher chance in being prevented earlier. The main idea is to eradicate the virus as soon as it enters the body by marking it with antibodies; signaling the immune system to dispose of it. However, the antibodies must be trained to recognize the virus. They can be trained by inserting an object similar to the virus allowing them to learn to recognize and surround the inserted object. In response to this, molecular dynamics simulation was chosen to study the antibody-virus interaction. In this work, two-dimensional case that involves HPV and immunoglobulin (Ig) was studied and observed. Two types of objects will be defined; one stands for HPV while another stands for antibodies. The interaction between the two objects will be governed by two forces; Coulomb force and repulsive contact force. Through the definition of some rules and condition, the antibodies' motion was observed. The influence of antibody concentration, and the antibody's type and their appearance sequence were observed both quantitatively and visually. Keywords: antibody-virus interaction, molecular dynamics, HPV, immunoglobulin.

q-bio.CB↗

Self-Motion Mechanism Of Chained Spherical Grains Cells

Cells are modeled with spherical grains connected each other. Each cell can shrink and swell by transporting its fluid content to other connected neighbor while still maintaining its density at constant value. As a spherical part of a cell swells it gains more pressure from its surrounding, while shrink state gains less pressure. Pressure difference between these two or more parts of cell will create motion force for the cell. For simplicity, cell is considered to have same density as its environment fluid and connections between parts of cell are virtually accommodated by a spring force. This model is also limited to 2-d case. Influence of parameters to cell motion will be presented. One grain cell shows no motion, while two and more grains cell can perform a motion.

physics.bio-ph↗

Model and Visualization of Ray Tracing using JavaScript and HTML5 for TIR Measurement System Equipped with Equilateral Right Angle Prism

Trace of ray deviated by a prism, which is common in a TIR (total internal reflection) measurement system, is sometimes difficult to manage, especially if the prism is an equilateral right angle prism (ERAP). The point where the ray is reflected inside the right-angle prism is also changed as the angle of incident ray changed. In an ATR (attenuated total reflectance) measurement system, range of this point determines size of sample. Using JavaScript and HTML5 model and visualization of ray tracing deviated by an ERAP is perform and reported in this work. Some data are obtained from this visualization and an empirical relations between angle of incident ray source θ_S, angle of ray detector hand θ_D, and angle of ray detector θ'_D are presented for radial position of ray source R_S, radial position of ray detector R_D, height of right-angle prism t, and refractive index of the prism n. Keywords: deviation angle, equilateral right angle prism, total internal reflection, JavaScript, HTML5.

physics.optics↗

Novel Giant Magnetoresistance Model using Multiple Barrier Potential

This paper proposes a new model for Giant Magnetoresistance (GMR) and calculates its typical graph qualitatively. The model foundation is the microscopic mechanism in GMR, where the GMR effect can be explained by intrinsic and extrinsic potential. The potentials are spin-dependent. The potentials determine the transmission probability then it will give conductance value. Here, the multiple barrier potential model is proposed as the new GMR model. The transmission probability is determined using transfer matrix method. It was found that this model is fit qualitatively with the typical GMR graph.

cond-mat.mtrl-sci↗