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Cocoa farming households carry out various livelihood strategies to maintain their survival. The decline in cocoa production is caused by pests and diseases, climate change, bad seeds, and the farmers' cocoa plants are old. These constraints will affect the condition of cocoa farmer households. This study aims to identify the livelihood strategies and structures carried out by cocoa farming households. The method used in this study uses a quantitative approach using a questionnaire supported by a qualitative approach through in-depth interviews. The research respondents consisted of 30 cocoa farming households in Polewali Mandar Regency. The results of this study show that the livelihood strategies used by cocoa farmer households are engineering income sources and income diversification. The average livelihood structure of cocoa farmer households comes from the non-farm sector. [ABSTRACT FROM AUTHOR]

Single-element wing means adding certain components to improve the aerodynamic performance of the wing. The enhance components can be in the form of high lift devices or control surfaces. Flap is one of the components commonly used in light aircraft and commercial aircraft today. The deflection exhibited by the flaps on the wings during flight will have an effect on the performance of the aircraft. This study uses a wing with airfoil NACA 43018 using flap deflection δf = 0o, 15o and 30o compared to the performance of plain wing. The angle of attack used is α=0o, 2o, 4o, 6o, 8o, 10o,12o,15o,17o,19o and 20o. This numerical simulation uses a turbulent model k-ε realizable with Re=3.76 x105. The use of flap deflection variations gives an increase in the value of the drag coefficient and also the lift coefficient. In the use of angle of attack α = 6o, flap deflection δf = 0o showed the best aerodynamic performance but after that flap deflection δf = 15o showed better improvement. The effect of the gap size of the flap cannot be ignored because it affects the flow pattern around the wingtip and the area towards the midspan. [ABSTRACT FROM AUTHOR]

Hot air rising (or convective airflow) is transparent gases (fluids) and invisible. The visualization of fluid dynamics is of considerable interest due to its widespread applications. Background-oriented schlieren (BOS) as an optical method offers numerous advantages in the visualization since this method can provide simple, non-contact, non-invasive, and non-intrusive measurements. The performance of the BOS method strongly depends on the background patterns. Implementing the BOS method usually use random dot patterns as a background and the digital image correlation (DIC) algorithm as a software tool for image processing. However, this algorithm can also analyze the regular pattern background. So far, the experimental BOS using regular patterns background and the DIC algorithm are rarely developed. In this paper, three types of regular patterns, including a checkerboard (crossed fringes), vertical and horizontal fringes patterns, have been proposed as the background in the experimental BOS. During the experiment, a camera is continuously focusing on the background patterns. At the same time, a convective airflow is in the position between the background and the camera. The digital camera records the change of background patterns with and without a convective airflow, giving them distorted and undistorted (reference) images. By comparing both images, the DIC algorithm estimates the pixel displacements. Finally, the interpolation method reconstructs the pixel displacements field into an image resembling the convective airflow. For calibration purposes, the developed BOS uses the known deflection angle of a wedge prism as a standard to assess the accuracy. As a testing, the calibrated BOS visualize the convective airflow induced by a hot object as a heat source, such as candle flame and hot plate. The results show that all the types of backgrounds in the experimental BOS has created image, visualized and distinguished the fluid dynamics of convective airflow. Also, the developed BOS can calculate quantitatively the magnitude of pixel displacements that are proportional to density (or refractive index) gradients of the convective airflow. Thus, the developed BOS can detect an invisible phenomenon and potentially measure density (or refractive index) fluids and other transparent materials. [ABSTRACT FROM AUTHOR]

Sometimes, in certain conditions, we have to build buildings on contours that have different elevations, such as in hilly areas. The building that is built must also be designed to withstand earthquakes in accordance with the applicable standard, namely SNI 1726 2019. The magnitude of this earthquake load is influenced by several factors, ranging from the gravity load on the building, building risk factors, soil site class, and the structural system used. In addition, the configuration of the building also has a significant influence. This is where the configuration of the building is determined by the architectural design and the existing natural conditions. With the advancement of technology, this research can be assisted by the ETABS application, which can see the behavior of the building model from several angles. The building model is made of 10 floors with a slope of 0, 5, 10, 15, and 20 degrees. From the results, it can be seen that the fundamental period decreased from 2.258 – 2.116 sec in the Y direction, which indicates that the increasing slope of the building causes the column to shorten on one side of the building, which makes the building stiffer on one side. The capital participating mass ratio also decreases for each mode, where the 2 translational and 3 rotational modes are almost interchangeable because the value is<50% which can cause a large torque. The center mass displacement diaphragm on the 6th floor and below exceeds the maximum limit with a max value of 80 mm, with the largest deviation value in the Y direction earthquake on the 4th floor with a value of 109 mm, and the irregular torsion on the ground floor exceeds the limit, especially in the Y direction earthquake, where the largest value of the torsion ratio in the Y direction is up to 1.758; with increasing slope, the value is greater. Frame forces also decreased at M2 and M3, but axial forces remained constant. The value can be reduced because the load will be transferred to the shortest side of the building. [ABSTRACT FROM AUTHOR]

In medicals, use of ultrasound wave requires a safe treatment with no human effects. The uncontrolled intenities of the ultrasound sources leads to potential risk of thermal and cause ineffective treatment to the patient. This intensity is a main physical parameter used, therefore this parameter must be set and controlled accurately. So far, the hydrophone probe method is considered to become a gold standard in ultrasound intensity beams visualization. Unfortunately, the method is time-consuming, intrusive, and off-axis measurements. Nowadays, an optical method called background-oriented schlieren (BOS) imaging has been developed as an alternative to the probe method. This optical method strongly depends on the background patterns that currently use the random dot patterns and the digital image correlation (DIC) algorithm as a background. The interesting one is this algorithm can also be used to analyze the image of regular pattern background and being developed in this researched especially in the visualization of ultrasound intensity beams. This paper reports that new technique of development of BOS imaging to visualize the ultrasound beams (field) produced by a 1-MHz frequency therapeutic transducer operated in continuous-wave mode. The results show that the developed BOS imaging can visualize and distinguish the ultrasound beams even with the various intensities. This results are promising to be used for ultrasound beams calibration or accuracy assessment to ensure patient safety in medical applications. [ABSTRACT FROM AUTHOR]

Combining several high lift devices on airplanes is a natural thing. High lift devices are used to control aircraft movements and improve aerodynamic performance. The landing phase in flight is vulnerable and requires good control, especially aircraft wing control that uses high lift devices. High lift devices such as slat clearance and flap are commonly used, but variations in their geometry always produce different and interesting phenomena to be explored further. This research was conducted numerically on a rectangular wing with NACA 43018 airfoil. This study will compare the rectangular wing with a wing that uses a combination of slat slots (slat clearance) and flaps on the landing process. The angle of attack used in this study is (α) = 0°, 2°, 4°, 6°, 8°, 10°,12°,15°, 16°,17°,19°, and 20°. Ansys 18.1 software with k-ε Realizable turbulent model is used to help the numerical simulation. The combination of slat clearance and flap results in a higher total drag coefficient and higher lift coefficient. However, the rectangular wing produces better aerodynamic performance. Visualizing the velocity path line and wall shear stress shows that the rectangular wing is easier to separate than the combined flap δT = 30° and slat δL = 0°. [ABSTRACT FROM AUTHOR]

Source of refraction seismic waves currently are using a sledgehammer because of its convenience to improve data quality and its efficiency. Therefore firecrackers were tested as a source of seismic vibrations. This study aims to compare the use of firecrackers in terms of data quality and efficiency in the field. The methodology used in this study was to compare the acquisition data generated from seismic sources of firecrackers and the use of sledgehammers. The results are then analyzed both qualitatively and quantitatively. The use of firecrackers weighing 4, 5, and 6 grams resulted in a relatively equal amplitude compared to the use of a sledgehammer. The results of the frequency spectral analysis showed that the firecracker source had a dominant low frequency ranging from 30 to 80 Hz. Source of firecrackers and sledgehammer, dominant has the highest frequency is at 40 Hz so that firecrackers can be used as a source of seismic waves in seismic refraction. The first break made by the firecracker source was quieter than the one produced by the sledgehammer source. [ABSTRACT FROM AUTHOR]

Detection of CO2 and SO2 gases is crucial because they are indicators of volcanic eruption activity. The release of CO2 from the volcano with an increasing concentration is an indicator that an eruption will occur, while the increase in the release of SO2 occurs after the eruption of Merapi. Currently, studies on the detection of volcanic gases are still using the in-situ technique where the gas will be taken directly at the source and then analyzed in the laboratory. This is of course very dangerous for the safety of the monitor and also the durability of the tool because the contact system is reactive and corrosive. This study developed a non-contact CO2 and SO2 gas detection system using an infrared camera. The infrared camera produces optical imaging with the unique characteristics of both CO2 and SO2 gases. A new challenge in gas detection using optical imaging is when CO2 and SO2 are mixed. However, it was re-reported in this study that mixed gas optical imaging produces certain unique patterns as an indication of gas detection with a non-contact system designed to detect gas in single gas or mixed gas. [ABSTRACT FROM AUTHOR]

In Central Lombok District, the allocation of funds for the rehabilitation of elementary schools is very small compared to the number of schools that need reconstruction. The percentage of classroom rehabilitation work based on the target schools only reached 9.96%. Consequently, it needs to study to analyze the damage level of buildings and find out the most influenced criteria in formulating decisions for selecting school priorities that must be rehabilitated. Due to controlled aspects and standards are quite a lot and more sophisticated, accordingly the Analytical Hierarchy Process (AHP) method is the proper method for solving these complex problems. The sample in this study was 13 of the 25 schools that received special funds in 2018. The application of the AHP method was preceded by a survey involving experts who were competent in their fields. The results showed that the number of schools with moderate damage was six and severely damaged as many as seven schools. At the same time, based on the order of priority, building repairs are determined by the most influential criteria, namely the level of damage and primary education data. [ABSTRACT FROM AUTHOR]

The Hammer test as one of non-destructive concrete strength test should in a non-moist structural condition to produce a high accuracy reading. Since, the strength is only taken from the concrete surface which can be affected by moisture and does not represent the overall properties of the concrete samples. For this reason, hammer test is necessary to compare between the destructive test using a Compression Testing Machine (CTM) a standard concrete strength test and Hammer test. This research used normal concrete with the concrete strength target of 20 MPa, with variations in moisture measured at 0 day, 1 day, 2 days, 3 days, 4 days, 5 days, 6 days, 9 days 14 days and 21 days after removal from curing chamber, as well as the dried samples with 2 days oven to obtain low moisture. The concrete strength test includes compressive and split tensile strength using a cube sample with 15 cm size. The result shows that the compressive strength value of the Hammer test is lower than the CTM test of 12.34 MPa at 40% moisture, and the difference is higher as the moisture of the concrete surface increases. At various moisture content, the ratio of split tensile strength towards the compressive strength ranges 9.94% - 13.65%. [ABSTRACT FROM AUTHOR]

This research investigated the relationship between science content knowledge and mathematics content knowledge in relation to the preservice primary school teachers' conceptions of STEM education in Indonesia. The survey method was used to collect data about science content knowledge, mathematics content knowledge, and STEM conceptualizations. A total of 139 preservice primary school teachers participated in this study. The results indicate that science and mathematics content knowledge can influence preservice primary school teachers' conceptions of STEM education. There is no significant relationship between gender and STEM education conceptualization was detected. [ABSTRACT FROM AUTHOR]

Once introduced into rhizosphere, plant parasitic nematodes are difficult to control because they are persistent in soil by surviving on alternative hosts. Several minor legume species are suppressive to plant parasitic nematode population. This study was aimed at observing the plant parasitic nematode fauna infesting three minor legumes, velvet bean (Mucuna pruriens), lablab bean (Lablab purpureus), and jack bean (Canavalia ensiformis) in a field experiment. Soil samples were collected from plots of selected accessions planted in rainfed field at Cikeumeuh Experiment Station, Bogor on six sampling dates from August 2019 until March 2020. Microscopic analysis of extracted soil found two ectoparasitic and three endopatasitic nematodes infesting the legume rhizosphere. From the highest to the least abundant number, these were Criconemella, Helicotylenchus, Rotylenchulus, Pratylenchus, and Meloidogyne. At the beginning of the planting season the number of nematode ranged from 0 to 57 per 200 ml soil which then fluctuated during the crop growing season. Slight differences in nematode population densities among accessions within a legume species were observed. Jack bean supported the least number of nematode, followed by lablab bean and velvet bean. Further studies under controlled environment are necessary to assess nematode multiplication on potential legume accessions with reducing effect on nematode population. [ABSTRACT FROM AUTHOR]

In order to maintain the availability of electricity supply, a failure at the power plant is mandatory to be prevented. If damage has occurred, analysis of the root cause of failure must be prioritized to resolve the problem and prevent further damage. One of the important units in a power plant is a boiler that has a role as a steam generator producing the steam by changing the water in the liquid to the vapor phase. The quality of the (feed) water becomes one crucial factor in determining the lifetime of a boiler. Moreover, some factors related to the process variable control such as velocity, temperature, pressure, and flow rate of fluid should follow the specified design. Otherwise, the failure can occur, resulting in the unit shutting down, thus stopping the electric production. In this paper, the mechanism of the leakages that occurred at boiler bottom wall tubes of the steam power plant was investigated. Quality of (feed) water and several factors associated with the leakages such as temperature, pressure, and fluid characteristic are mainly considered the suspect contributing to the damage. Further to this, macro-and microstructural observations at the leaked tubes as the physical analysis were done. Analysis of chemical composition was performed to the (feed) water. Other factors concerned with the failure were also observed to validate the root cause analysis and mechanism of the leakages. Chemical analysis of (feed) water shows that the excess content of hydrazine (N2H4) as an inhibitor of corrosion is 100 times more than specified representing the low-quality level of (feed) water which significantly influences the aggressiveness of the water. In addition to this, an intentional turbulence of the flow rate of (feed) water shown by having a Reynold number of 33,000 together with the contaminated (feed) water significantly increases the risk of failure at the inner tube. Macro observation exhibits a sectional reduction on the upper curve radius at the leaked tubes indicating that a loss of product reaction between the outer tube surface with a suspicious variable occurred during the operation. Moreover, a damage to the protective magnetite layer was particularly found around the leakage denoting that a local failure happened at the inner surface tube. On the other hand, micro observation shows a local plastic deformation implying an increase of high local temperature around the leaked tubes. To conclude, the tube leakages are mainly resulted from the collaboration of suspicious factors originating from the ambient environment on both sides of the tubes. Indeed, the low level of water quality, the high turbulence of flow rate, and the increasing of local temperature during operation at inner tubes successfully caused the erosion corrosion. While the suspicious factor at outer tube, such as the fuel, led to induce the pitting corrosion. In this case, both corrosions are responsible factors to encourage the failure. [ABSTRACT FROM AUTHOR]

Airfoil is an aerodynamic structure that is widely used in aircraft wings, UAVs, and fluid engines such as pumps, compressors, and turbines. The airfoil on the UAV wing is used to lift the UAV body where the pressure difference between the top and bottom of the airfoil causes the UAV to get a lift. Improving airfoil performance can be done in various ways, one of which is changing the angle of inclination in the airfoil range (swept angle). This is often seen in almost all types of commercial aircraft such as the Boeing 777 and Airbus 380. The method used in this study is a three-dimensional numerical simulation using Ansys 19.1 software. The specimens were Eppler 562 airfoil with a chord length of 200 mm, aspect ratio (AR) of 5, angle of attack 0°, 2°, 4°, 6°, 8°, 10°,12°,15°, 16°,17°,19°, and 20°. The variation of the swept-back used is angle Λ=0° (unswept), 15°, and 30°. Fluid flow is flowing air with the Reynolds number (Re)=2.34 × 104 in unsteady conditions. From this research, it was found that the variation of the swept-back will change the direction of flow to the wingtip and away from the wing root. This change in flow direction will reduce the occurrence of a vortex-shaped streamline that occurs on the unswept or rectangular wing. However, the variation of the swept-back will increase the tip vortex. [ABSTRACT FROM AUTHOR]

Airfoil is an aerodynamic model that is widely used both on aircraft wings, Unmanned Aerial Vehicle (UAV) and fluid machines such as pumps, compressors, and turbines. The airfoil on aircraft wings with the resulting lift force is used to lift the entire aircraft. Therefore, the researchers concentrate more on wing modification so that the resulting lift is more optimal. Increased performance of the airfoil on the wing can be done in various ways, one of which is adding a winglet to reduce drag. It is hoped that a large enough lift and drag ratio will improve aircraft performance. This research was conducted by numerical simulation using Ansys 19.0. with turbulent model k-ω SST. The velocity flow rate used is 10 m / s (Re = 2.3 × 104) with α = 0°, 2°, 4°, 6°, 8°, 10°, 12°, 15°, 16°, 17°, 19° and 20°. The test model is an Eppler 562 (E562) airfoil with and without a winglet. From this study, tip vortex was seen in plain wings, forward wingtip fence and rearward wingtip fence with lower speeds. In the area that has been separated (wake) which is indicated by a lower speed in the three configurations × = 1c. In the z = 1.5c area, it is shown that there is a pathline pattern difference between the three configurations. It is shown that the influence of the three-dimensional flow on the rearward wingtip fence where there is a higher velocity in the upper surface area. In the trailing edge, z = 1.9 shows that there is a pathline from the lower surface to the upper surface in the plain wing and rearward wingtip fence. [ABSTRACT FROM AUTHOR]

Airfoil modeling is very important especially in determining the airfoil's performance. One very important in the airfoil design is how to make airfoil with high lift and low drag to obtain a large lift to drag ratio. In this study, the design was carried out with Eppler 562 wing airfoil by adding an endplate at the end of the wing. Endplate used in the form of forward wingtip fence. The addition of endplate at the tip of the wing aims to reduce the occurrence of tip vortex. The emergence of a tip vortex is due to the flow from the lower surface to the upper surface. These tip vortex can cause induced downwash velocities and reduce effective angle of attack. This research is conducted by numerical simulation using simulation software with turbulent model k-ω SST. Freestream flow rate to be used is 10 m/s with angle of attack (α) = 0°, 2°, 4°, 6°, 8°, 10°,12° 15°, 17° and 19°. On forward wingtip fence cant angel 90° produce higher performance than other wing start at α = 6° while forward wingtip fence cant angel 75° produce better performance at α =19°. The tip vortices formed by the winglet produce very different shapes to each other and it appears to be a significant effect of the flow field above the wing surface. These vortices will change shape when the angle of attack of the model is changed. The values of the vortices behind the winglet are also different which indicate the effect of induced drag. [ABSTRACT FROM AUTHOR]

To produce lift on the wing of the aircraft, pressure distribution on the upper surface of the wing must be lower than the pressure on the lower of the wing. This can be done by making the air passage on the upper surface is longer than that on the bottom surface, or making the wing's relative angle to the direction of the incoming stream of air. Air will tend to flow from areas with high pressure to areas with low pressure. The pressure difference between lower surface of the wing higher than the top surface of the wing also results in the occurrence of this airflow. The place that allows for the occurrence of "leakage" of this air is at the tip of the wing. The flow from lower surface to the upper upper surface of the wings produces a vortex flow similar to a small tornado known as wingtip vortices. This whirl causes the air tend to flow downward on the wing area, and referred to as the term downwash. One modification on the aircraft wing to reduce the impact of the vortex tip is the use of the winglet on the tip of the aircraft wing. This has been widely applied to the latest commercial aircraft to improve the efficiency of the aircraft. The numerical study was done using CFD software with 3D geometry configuration. The geometry of the specimen is airplane wing Eppler 562 with chord length of 0.036 m, swept angle 0° and modification of winglet type rearward wingtip fence winglet with cant angle of 75°. The airflow with velocity at the inlet of 10 m /s. The turbulent modeling is k-ω SST. Present study uses hybrid mesh with boundary layer mesh method. From the simulation results it is shown that there is an increase in lift coefficient (CL) and an increase in drag coefficient (CD) along with the increase of angle of attack. In rearward wingtip fence with cant angle 0o produce CL/CD better than cant angle 75o and plain wing. Rearward wingtip fence shows optimum performance of α = 8o settings compared to plain wing. [ABSTRACT FROM AUTHOR]

Wings are one of the aircraft components that play an important role in generating lift. One of the important factors affecting lift on the wing is the aspect ratio of the wing. The theory shows that the use of wings with infinite span length (infinite wing) is the most ideal wing design, but in fact it is impossible to make wings of infinite length. Therefore the wing's length is limited and made with dimensions proportional to the fuselage length of the aircraft. The span length of the aircraft is limited, making a three-dimensional separation on the wing tip section which will form a secondary flow, where this flow gives loss on the performance of the aircraft as it reduces the effective area of the wing and increase the wing drag. One modification on the aircraft wing to reduce the impact of the vortex tip is the use of the winglet on the tip portion of the wing. This has been widely applied to the latest commercial aircraft to improve the efficiency of the aircraft and UAV (Unmanned Aerial Vehicle). The study using numerical simulation was done with simulation software with 3D geometric configuration. The geometry of the model is UAV wing Eppler 562 with chord length of 0.36m, swept angle 0° and modification of whitcomb winglet with cant angle 90°. The was performed at inlet airflow of 10m / s and the pressure at the outlet was 0Pa (gage). The turbulent modeling used is k-ω SST. Discrete method is hybrid mesh with boundary layer mesh method. The results of flow visualization show that withcomb winglet can improve wing performance effectively at high angles of attack, especially at angle α = 8° and α = 10°, which CL/CD higher than airfoil without winglet. The rearward wingtip fence effective CL/CD is higher than airfoil without winglet after angle α = 10°. [ABSTRACT FROM AUTHOR]