Negative X-axis Research Articles

PENGARUH PARAMETER PEMESINAN TERHADAP KEKASARAN PERMUKAAN AI6061BE PADA PEMESINAN CNC MINI 500 WATT MENGGUNAKAN PAHAT KARBIDA STRAIGHT ENDMILL

The role of automatic machining with the help of computer programming such as Computer Numerically Controlled (CNC) has become commonplace today in both large and small industrial sectors or micro industry. CNC is a manufacturing process where previously programmed computer software is converted into code that can automate machining movements, one of which is the milling or lathe process. CNC performance is determined by machining output power. For micro industrial or laboratory scale, CNC with low power is usually used to cut soft materials such as wood, acrylic, aluminum and others. This is the basis for this research to look at the influence of machining parameters such as speed, depth of cut and feed rate on the surface roughness (Ra) of AI6061BE aluminum workpieces in the dry machining process on a mini CNC unit with a maximum spindle power of 500 watts. This research uses an experimental design based on the Taguchi method and takes the form of an L16 (43) orthogonal matrix. The chisel used is a Straight End Mill 2 fluke carbide chisel. The experiment was carried out 4 times cutting in the positive x-axis direction and 4 times in the negative x-axis direction for each variation of machining parameters. From the test results, surface roughness, feed rate is a parameter that is more influential than speed and depth of cut.

Mechanical anisotropy induced by the competition between twinning and basal slip of AZ31 magnesium alloy under biaxial tension

The mechanical behavior of a hot-rolled Mg AZ31 plate was studied under biaxial tensions along two perpendicular loading axes of x and y in the ND-TD plane, with the x-axis aligned at a 45° counterclockwise angle from the TD (ND and TD refer to the normal direction and transverse direction). A complex strain partitioning in two loading axes is observed with the variation of stress ratio σxx:σyy. For σxx:σyy= 1:1 and 1:1.5, the strains along the x- and y-axes, εxx and εyy, are both positive. However, With the stress ratio of σxx:σyy= 1:3, εyy remains positive, while εxx becomes negative. Interestingly, for σxx:σyy = 1:2, εxx changes from negative during the early stage of loading to positive upon failure. Crystal plasticity simulations and theoretical calculations reveal that the observed strain transition. The reasons for the strain transition with stress ratio is related to the competition between {101¯2} twinning and basal slip. For {101¯2} twinning, the accommodated strains by most of the twins are εxx>0 and εyy>0 for all the stress ratios considered. For basal slip, most of the basal variants accommodate a positive y-axis strain, while for loading cases with low stress ratios, most of the basal variants result in a negative x-axis strain. As the stress ratio decreases, basal slip becomes more active, while the activity of {101¯2} twinning gradually decreases, leading to the observed strain transition. For σxx:σyy = 1:2, the transition from negative to positive is related to the increasing activity of {101¯2} twinning with strain. Theoretical calculations reveal that the competition of basal slip and {101¯2} twinning under biaxial tension is determined by the variation of their Schmid factors with σxx:σyy.

Flow and heat transfer profiles in a heat exchanger tube equipped with X-V baffles (XVB): A numerical analysis

Simulations of laminar air flow and thermal configurations through a heat exchanger tube (HXT) equipped with X-V baffles (XVB) are performed. The Reynolds number is between 100 – 2000. The current numerical problem is solved by a numerical method (the finite volume analysis). Effects of the XVB sizes, the XVB distances and the flow directions on the flow and thermal profiles are discussed. The XVB size (b/D) is set between 0.05 – 0.20 and the XVB distance (P/D) is set to 1, 1.5 and 2. X-axis is the flow axis. The positive and negative x-axis are investigated. Two baffle configurations (Type I and II) are compared. The streamlines, vortex flows, temperature profiles and Nusselt number profiles in the HXT installed with these two XVB configurations (Type I and II) are described. The variations for the friction factor ratio (f/f0), Nusselt number ratio (Nu/Nu0) and thermal enhancement factor (TEF) within the HXT equipped with the XVB are presented. In addition, the TEF of 4.07 is found to be the best value for the present investigation.

Improvement of Pacific White Shrimp (Litopenaeus vannamei) Drying Characteristics and Quality Attributes by a Combination of Salting Pretreatment and Microwave.

This study investigated the effects of salting pretreatment and microwave (MW) power on drying characteristics, water distribution and quality attributes of Pacific white shrimp (Litopenaeus vannamei). With increasing salt concentration (0–8%, w/v) and MW power (300–900 W), the drying time of shrimp was shortened by 15.15–28.57%, compared with the untreated samples. Regarding the quality of dried shrimp, increasing the salt concentration and MW power increased the hardness (from 13,073.6 to 24,556.5 g), while the springiness, color parameters and astaxanthin content showed an initial decrease but a later increase trend. Low field nuclear magnetic resonance (LF-NMR) demonstrated that the T2 curve of the pretreated samples moved toward the negative x-axis and the immobilized water content decreased with increasing salt concentration. E-nose showed that volatile components were different and could be obviously distinguished at different salt concentrations and MW powers. Raman spectroscopy illustrated that the protein secondary structure of dried shrimp was altered by salting pretreatment and drying conditions, and the lowest conversion degree of α-helix to β-sheet of dried shrimp was obtained at the salt concentration of 4% (w/v) and MW power of 500 W. By comprehensively considering the drying time and quality attributes, the combination of 4% (w/v) salt and 500 W MW power was concluded as the best drying conditions for shrimp using a microwave. The results could provide an innovative combination of salt pretreatment and MW drying with suitable processing conditions for producing high-quality dried shrimp.

Bearing Characteristics of Tripod Bucket Jacket Foundation for Offshore Wind Turbines in Sand under Monotonic Loads

Tripod bucket jacket foundation is an alternative foundation solution for deep-sea wind farms. This paper analyzes and compares the bearing characteristics of two tripod bucket jacket foundations with different height-diameter ratios, the tripod suction pile jacket foundation (TSPJF) and tripod bucket jacket foundation (TBJF), under different monotonic loads. The bearing modes of the two foundations under the vertical loads are different. The ultimate vertical load is mainly borne by the inside frictional resistance for the TSPJF, while it is mainly borne by the lid resistance for the TBJF. The foundations will take place translation and rotation under horizontal load. Under the positive x-axis loading, the vertical resistance of the TSPJF and TBJF is mainly composed of the soil resistance on the 1# bucket lid, the inside and outside frictional resistance. Under the negative x-axis loading condition, the vertical resistance is mainly composed of the inside and outside frictional resistance of buckets. The ultimate moment capacities of the TSPJF and TBJF in loading of the single bucket in compression is significantly larger than that in loading of the single bucket in tension. The failure mode of the TSPJF and TBJF in loading of the single bucket in tension is the pull-out failure of the bucket in tension.

Interaction of shear waves with semi-infinite moving crack inside of a orthotropic media

The present work investigates the motion of a semi-infinite moving crack inside a semi-infinite half-space of orthotropic medium subjected to anti-plane shear wave. The crack is located at a finite depth from the surface of semi-infinite orthotropic medium. Our aim is to examine how such anisotropy and geometric parameters can be adjusted to reduce the magnitude of stress intensity factor (SIF) to control the crack propagation near the crack tip region. As mathematical tools, Fourier transformation and inverse Fourier transformation techniques are employed to convert the governing mixed boundary value problem to the well-known Weiner-Hopf equation with suitable boundary conditions. Some physical quantities such as SIF at the crack tip and crack opening displacement (COD) around the crack tip have been derived. Graphical exhibition has been carried out to show the impact of relevant parameters such as crack velocity, layer depth from the surface to crack and orthotropic material properties on SIF and COD. The numerical results show that SIF decay with crack depth from the layer. It is also observed that SIF decreases with an increase in crack velocity and finally tends to zero as crack velocity approches near SH-wave velocity. Also, the value of COD decays as we move along the damage near the crack tip along negative x-axis and finally tends to zero at the crack tip. This behavior of COD is consistent with the physical nature of the semi-infinite crack of the problem. The results are validated for isotropic material with some reported work and are well in agreement. The study of these physical quantities (SIF, COD) ensures the arrest of onset of crack expansion by monitoring geometric parameters and wave velocity to avoid fracture.

Perancangan Model Stacker Crane Flexible Manufacturing System untuk Pembelajaran di Institusi Pendidikan

Flexible Manufacturing System (FMS) is one of the modern production systems that support the implementation of Industry 4.0. An educational institution plans to build an FMS model for learning the modern production systems. The FMS is a manufacturing system consisting of a set of automatic workstations connected to a material handling system where all activities are controlled by a computer system. The material handling system consists of a material storage system and a transportation system, one example of a transportation system is the stacker crane. In this research, the stacker crane model has been built which consists of three main components, which are the bottom frame, the mast, and the carriage. This component is equipped with stepper motors, leadscrews that are controlled by the micro controller and an application on Android. The stacker crane model is tested to retrieve and deliver the stereofoam material model to the destination which is controlled by the user using an application on Android. The characteristics of the stacker crane model can move the workpiece with a maximum error of 2 mm in the positive x-axis direction, 2 mm in the negative x-axis movement, up to 2 mm positive y-axis, downward at negative y-axis direction 2 mm.

Analisis sudut panel solar cell terhadap daya output dan efisiensi yang dihasilkan

One of the natural potentials as a source of electrical energy is solar energy. The sun is the main energy source for most of the processes that occur on the surface of the earth. Solar radiation received by the earth's surface is a fundamental input for many aspects, mainly an important parameter in the application of solar cells as electricity generation. Sun cells are devices that can convert sunlight into electrical energy. In this study the data collection of solar cell panel data is collected which includes the solar radiation data, the voltage data generated and the electric current data generated at each variation of the tilt angle 0o, 8o, and 16o. This study aims to discover the effect of changes in the slope angle of solar cell panels on the efficiency of solar power generation systems. The study method used is an experimental development method which is carried out by using the tilt angle variation of the solar panel. The angle used by taking the tilt angle of the solar panel on the negative x-axis which aims to find the maximum tilt angle value. From the test results of 50 Watt Peak (WP) solar power plant installation, it can be concluded that the highest efficiency occurs at an angle of 16o and at 09:00 with a value of 46.076 %, then the second occurs at an angle of 8o and at 09:00 with a value of 45,052 %, then the lowest efficiency occurs at a slope angle of 0o and at 09:00 with a value of 43,986 %. Keywords: Angles, 50 WP panel, solar cell, power output, & efficiency.

Analysis of Magnetic Particle Agglomeration Structure and Interaction Forces Between Magnetic Particles

Chain-like and diamond-shaped magnetic particle agglomeration (MPA) commonly forming in a weak magnetic field are simulated based on the finite element method (FEM), and the effects of particle diameter, magnetic field strength, particle relative magnetic permeability, and particle number in magnetic particle chains (MPCs) and diamond-shaped MPA on the strength of MPA are analysed in detail. The results show that magnetic forces on the centre contact points (CCPs) of MPA are positively correlated with the particle diameter, magnetic field strength, particle relative magnetic permeability, and particle number. In addition, the forces on the CCPs of the MPCs (N=2) have a square relationship with the particle diameter and magnetic field strength and have a power relationship of 1.25 with the particle relative magnetic permeability. The forces on each contact point decrease slowly from the centre to both ends in the MPCs and then rapidly decrease to one value (approximately 0.779 times the forces on the CCPs). As for the diamond-shaped MPA, with the increase in the angle α between the magnetic field and axis of diamond-shaped MPA, the force magnitude of the particle entrained parallelly in the diamond-shaped MPA shows a trend of a “cosine curve” shape and the minimum value is 2109 times that of the entrained particle’s gravity. The angle θ between the direction of the force and the negative X-axis shows a trend of a “sine curve” shape. When α = 25° and 155°, the angle θ of the force on the entrained particle reaches an extreme value, that is, θ = 21.87°. Only if the angle θ reaches 30º can the particle entrained parallelly escape from the diamond-shaped MPA. Thus, the diamond-shaped MPA remains in a stable state and it is difficult to disperse MPA by changing the direction of the magnetic field.

Development of static solar panel equipped by an active reflector based on LDR sensors

Solar panels are a very effective source of renewable energy in Indonesia. To increase the output power of solar panels, especially on the static solar panels, a reflector is required as an additional device. This paper describes development of a static solar panel equipped with an active reflector. Five LDR sensors are mounted on the top of the reflector, to detect the highest solar intensity. Meanwhile, a DC motor as a reflector drive system is mounted on the bottom of the reflector. The tilt angle of the solar panel is 450 to the negative x-axis and the reflector is 750 to the positive x-axis. The reflector will move in a semi-circular path, following the direction of the highest solar intensity detected by the LDR sensor. Three different reflectors used to optimize the output power, there are stainless steel, aluminium foil, and mirror. Solar panel with mirror reflector produces the largest output power compared to other reflectors. The output power of this device increases 1.6 times to the solar panels without reflector.

Structural, optical, dielectric and magnetic properties of PVP coated magnetite (Fe3O4) nanoparticles

We report the synthesis of magnetite (Fe3O4) and polyvinylpyrrolidone (PVP) coated Fe3O4 nanoparticles by chemical co-precipitation route. X-ray diffraction (XRD) and transmission electron microscope (TEM) confirm the formation of inverse spinel structure of Fe3O4. XRD peaks of PVP coated Fe3O4 nanoparticles are broad and noisy as compared to Fe3O4. The broadness of peaks is due to small size and large defect density confirmed by energy dispersive spectroscopy (EDS) and scattered area electron diffraction (SAED). Noisy behavior is due to presence of PVP. Average particle size reduced from 10.36 ± 1.97 to 6.91 ± 1.89 nm for Fe3O4 and PVP coated Fe3O4, respectively. From EDS analysis, it is confirmed that the oxygen content reduced from 33.45 to 15.30 at.% with PVP coating. The oxygen content is reduced to half in case of PVP coated Fe3O4 as compared to uncoated Fe3O4. The reduction in oxygen content reveals enhancement in oxygen vacancies. Fourier transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA) confirm the PVP coating and the calculated value of thickness of the PVP layer on the surface of Fe3O4 is 2.4601 nm. Dielectric constant (er) and dielectric loss (tanδ) exhibits the dispersion behavior. Ac conductivity (σac) increases sharply at large frequencies, which is due to enhancement in charge density (liberated charge carriers from defects + conduction charge carriers). The variation in dielectric properties and conductivity is due to Maxwell Wagner interfacial polarization and hopping of charge carriers between Fe2+/Fe3+. Magnetic properties M(T) shows reduction of blocking temperature (TB) from 86 to 75 K for uncoated and PVP coated Fe3O4 nanoparticles. Shifting of TB to lower values is consistent with particle size reduction. M(H) loops at room temperature show typical superparamagnetic behavior. Reduction in saturation magnetization (Ms) is due to the presence of nonmagnetic polymer layer on the surface of Fe3O4 nanoparticles and large number of defects (oxygen vacancies). Field cooled M(H) loops at 5 K show the antisymmetric shift of coercive field along the negative x-axis. The exchange bias field HE enhances to 227 Oe in case of PVP coated Fe3O4 nanoparticles, which is double of the 125 Oe for uncoated nanoparticles. The enhancement in HE is due to smaller sized nanoparticles having large surface to volume ratio having large defect density (oxygen vacancies).

MHD boundary-layer flow due to a moving extensible surface

The flow due to a moving extensible sheet that obeys a more general stretching law is considered. The sheet occupies the negative x-axis and is moving continually in the positive x-direction, in an incompressible viscous and electrically conducting fluid. The sheet somehow disappears in a sink that is located at (x, y) = (0, 0). The governing system of partial differential equations is first transformed into a system of ordinary differential equations, and the transformed equations are solved numerically using a finite-difference scheme, namely the Keller-box method. The features of the flow and heat-transfer characteristics for different values of the governing parameters are analyzed and discussed. It is found that dual solutions exist for the flow near x = 0, where the velocity profiles show a reversed flow.

A Structural Basis for the Acute Effects of HIV Protease Inhibitors on GLUT4 Intrinsic Activity

Human immunodeficiency virus (HIV) protease inhibitors (PIs) act as reversible noncompetitive inhibitors of GLUT4 with binding affinities in the low micromolar range and are known to contribute to alterations in glucose homeostasis during treatment of HIV infection. As aspartyl protease inhibitors, these compounds all possess a core peptidomimetic structure together with flanking hydrophobic moieties. To determine the molecular basis for GLUT4 inhibition, a family of related oligopeptides containing structural elements found in PIs was screened for their ability to inhibit 2-deoxyglucose transport in primary rat adipocytes. The peptide oxybenzylcarbonyl-His-Phe-Phe-O-ethyl ester (zHFFe) was identified as a potent inhibitor of zero-trans glucose flux with a K(i) of 26 mum. Similar to PIs, transport inhibition by this peptide was acute, noncompetitive, and reversible. Within a Xenopus oocyte expression system, zHFFe acutely and reversibly inhibited GLUT4-mediated glucose uptake, whereas GLUT1 activity was unaffected at concentrations as high as 1 mm. The related photoactivatable peptide zHFF-p-benzoylphenylalanine-[(125)I]Tyr-O-ethyl ester selectively labeled GLUT4 in rat adipocytes and indinavir effectively protected against photolabeling. Furthermore, GLUT4 bound to a peptide affinity column containing the zHFF sequence and was eluted by indinavir. These data establish a structural basis for PI effects on GLUT4 activity and support the direct binding of PIs to the transport protein as the mechanism for acute inhibition of insulin-stimulated glucose uptake.

The effect of thermal transfer on the zeroing of the luminescence of quartz from recent glaciofluvial sediments

The natural optically stimulated luminescence (OSL) response of quartz grains extracted from a range of recent glaciofluvial and other glaciogenic sediments from Western Greenland is presented. All samples were deposited within the last 10 years, many only days or hours before collection. Consequently we would expect to measure zero or very small D E values had optical resetting of the OSL signal been complete. In the case of most samples. D E values in the range 0.5–10 Gy are observed, while higher values are observed for a handful of samples. However, the regenerated OSL growth curves, constructed after daylight exposure of at least several hours, also show large apparent D E values (negative x-axis intercepts). Corresponding samples from four different locations in the Indian Himalaya display similar OSL characteristics. The measurement of several regenerated OSL growth curves omitting the preheat procedure which normally precedes OSL measurement, confirms that a significant degree of thermal transfer is occurring during the preheating. It is this thermal transfer of charge during the preheat which is responsible for a significant contribution to the large apparent D E values observed for the regenerated OSL growth. In this paper we describe combined OSL and TL measurements which have been used to monitor the charge transfer in detail for one sample. An attempt is made to describe the charge transfer behaviour, and we discuss methods appropriate to eliminating the unwanted effects of this phenomenon during OSL dating. Preliminary results from the application of these techniques are presented, and the implications of these observations for the OSL dating of glaciogenic sediments are discussed.

Conformal invariance and critical systems with mixed boundary conditions

Conformal-invariance methods are applied to semi-infinite two-dimensional critical systems defined on the upper half-plane with different boundary conditions a and b on the positive and negative x-axis. (The half-space with ab boundary conditions is equivalent, under a conformal mapping, to a strip with boundary conditions a and b on opposite edges.) The conformal Ward identity is derived. The n-point correlation function in the system with mixed boundary conditions follows from the same differential equations as a particular bulk (2 n + 2)-point correlation function. We calculate all density profiles 〈 φ( r)〉 ab determined by the condition of degeneracy at levels 2 and 3. The profiles and pair correlation functions of the magnetization and the energy density in the Ising model with + − and + f (fixed-free) boundary conditions are obtained. Corresponding results for profiles in the Q-state Potts model are given. We also derive some useful general expressions for bulk four-point correlation functions involving operators degenerate at levels 2 and 3.

Generalised Stirling approximations to N!

Generalised asymptotic approximations to Gamma (x+1), which contain an arbitrary parameter, are derived both from the integral representation of the gamma function without assuming a knowledge of the Stirling series, and through elementary rearrangements of the Stirling series. By optimising the arbitrary parameter according to appropriate criteria, several known Stirling-like approximations are recovered in a unifying way. These are as compact as but numerically superior to the standard Stirling approximation, and are meaningful on intervals that even include parts of the negative x-axis. It is pointed out that these results-arrived at by elementary but generally applicable asymptotic techniques-can be exploited in physics teaching to demonstrate the power and utility of asymptotic methods in the analysis of a variety of physics problems.

Dependence of motion sickness in automobiles on the direction of linear acceleration.

Thirty-eight normal volunteers were tested in an ambulance car while being accelerated in one of the following positions: (1) sitting upright facing forward in the car, (2) lying supine on a stretcher head forward, (3) supine position head backward. Consecutive short period of negative horizontal acceleration (0.7-0.95 g) were achieved by brisk braking manoeuvres of the car, followed by weak reacceleration (0.15 g). Motion sickness symptoms were observed and recorded after each experiment using a special motion sickness scaling index which was weighted according to the strength of any particular symptom. The results indicate that horizontal linear acceleration in a car, such as experienced during multiple breaking manoeuvres, is an effective motion sickness provoking stimulus. Negative X-axis stimulation is more nauseogenic then acceleration in the Z-axis stimulation is more nauseogenic then acceleration in the Z-axis of the body.

Nausogenic properties of various dynamic and static force environments

Motion sickness can occur when an accelerating force acting on the human body repeatedly changes amplitude and direction or both. It also can occur without any motion after transfer into a constant force field significantly different from Earth-gravity. Dynamic and static causes of motion sickness can be distinguished accordingly. Space sickness, too, has dynamic as well as static aspects. Dynamic space sickness might depend on increased bilateral differential sensitivity of the peripheral and central vestibular apparatus, whereas static space sickness may be caused by erroneous compensation of bilaterial asymmetries of the otolith-system in the microgravity environment. Experiments in airplanes, cars and on a vestibular sled have shown that the susceptibility to motion sickness is highest for changes of acceleration in the negative X-axis (as compared to the other axes) of the body. During reciprocating linear accelerations on the vestibular sled, standstill periods of movement and the direction of movement cannot correctly be indicated, because the peripheral vestibular apparatus lacks true motion detectors.

The Bending Stress in a Cracked Plate on an Elastic Foundation

Classical Kirchhoff bending solutions for a normally loaded elastically supported flat plate containing a semi-infinite straight crack are obtained using an integral equation formulation. Because the effects of initial spherical plate curvature are related to those of an elastic foundation, the solution can be applied to the problem of a crack in an initially curved unsupported plate as well. The explicit nature of the stresses near the crack point is found to depend upon the inverse half power of the nondimensional distance from the point, r/(D/k)1/4, where D is the flexural rigidity of the plate and k the foundation modulus. The particular case of an infinite strip containing the crack along the negative x-axis and loaded by constant moments M* along y = ±y* is presented. The inverse half-power decay of stress is additionally damped by an exponential factor of the form exp(−λy*/2).

Relationship between the anatomical orientation of the interventricular septum and the manifest orientation of ventricular depolarization in dogs.

Exact anatomical orientation of the interventricular septum was compared with apparent direction of electrical activity during ventricular depolarization in 22 dogs. In 15 control animals, the mean orientation of a vector normal to the right septal surface was toward the front, to the right, and slightly headward. The mean orientation of the 10-msec. vector (QRS) was almost directly toward the front and slightly tailward. The mean orientation of the polar vector was to the left, slightly to the front, and slightly headward. The values for each of these means were obtained in spherical coordinates: anatomical vector--141.7 degrees azimuth, 20.2 degrees altitude; 10-msec. vector (QRS)--92.0 degrees azimuth, -9.4 degrees altitude; and polar vector--14.8 degrees azimuth, 20.0 degrees altitude. In 7 dogs, rotation of the heart to the right by means of previously implanted guy sutures consistently moved the 10-msec. vector to the right also, but there was simultaneous unpredictable deviation either headward or tailward of the electrical vector. Polar vector shift was not consistent. Rotational transformation of axes for each dog, bringing the vector of the right septal surface into coincidence with the negative X-axis, did not bring to a focus the scatter of orientations of either group of electrical vectors, indicating that variation in electrical position depends upon other factors in addition to variation in anatomical position.