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Vehicle routing problem (VRP) has a key role in logistics management. VRP plays a role in designing the optimal route used by a number of vehicles placed at the depot to serve a number of customers with known requests. To solve the VRP, the nearest neighbor algorithm used to get the most optimal results. The Nearest Neighbor algorithm is a heuristic method which is done by starting the starting point than looking for the nearest point. In this paper, algorithm nearest neighbour can save the distance of 13,14% and cost 13,17%.

The development of science and technology in the industrial period 4.0 needs to be improved through the improvement of human resources. The learning process in the industrial period 4.0 is required for the world of education to develop, especially in the field of technology. One of the learning models used is the Hybrid learning model by using schoology applications to assist students in improving process skills in basic physics course materials. Therefore, one of the objectives of this study is to find out the influence of hybrid learning models using schoology applications in basic physics courses in improving process skills in the face ofindustry 4.0. The population of this study is all students of the Faculty of Teacher Training and Education. Sampling techniques are used cluster random sampling where students as experimental classes that use hybrid learning models using schoology and math students as control classes using e learning models. The instrument used is a matterof process skills test. The resultof the study for the average value of the control class on pretes was 37.17 and the average postes score was 66.94. The average pretest score in the training experiment classwas 36.83 and the average postes score was 78.61, this suggests there is an influenceof hybrid learning models using schoology applications on process skills in basic physics courses.

All Grounding planning of a substation is important and various design applications are available using calculation uniform soil resistivity, even though actual resistivity data measured is more than one layer. This is caused by limited availability of the application in processing data only for resistivity one layer. Substation grounding grid application (ASPG) 1.0 can be used for designing grid grounding. The ASPG was developed from Lab View software and has ability to data process for resistivity two-layer that to refer IEEE Std. 80-2013. Grid grounding resistance is considering a combination of grid conductor and ground conductor. This paper discusses the calculation of the magnitude of substation grid grounding using formulas developed by Schwarz, Sulivan and Sunde. The design result obtained is more accurate in substitute resistivity for resistivity two-layer model and calculation grounding resistance substation.

Fatigue is the problem for all workers in the world. Fatigue can influence the work performance of the workers. A relaxation model to decrease the fatigue level had been developed before by the researcher, it is named TOM’S MODEL. By, the increasing of the technology, so this study tried to improve TOM’S MODEL into android-based application. The participants of the study were the workers in one university in Indonesia. There were fourty workers recruited for this study. The participants were involved in a series of treatment. Altogether there are five treatments included pre-test and post-test. The physical fatigue and mental fatigue measured by using Whole Body Reation Tester (WBRT) and Bourdon Wiersman. The results show that there is significant reducing of fatigue both physical and mental, after the participants applied the relaxation from the android application. The interview results show that the android-based application is easier to use since it is integrated in their cellular phone. They can use it at any time and place during their work without any problems. The movement in relaxation is also simple to follow. This application can be applied for all workers in any field.

Carbon charcoal was made from rambutan rods and used as an adsorbent. A gram 70/100 mesh size of adsorbent was then used to adsorb 100 ml of copper ion solution with a 70 ppm concentration. In this investigation, the batch procedure was used without shaking (naturally). The charcoal carbon rambutan ability to remove the copper ion was measured by AAS. The percentage result was 48,135% or about 33,694 ppm. SEM and EDX instrument analysis have applied to confirm the presence of copper ions on the adsorbent surface. The copper ion was found at a concentration of 0.09 percent of the total weight. The carbon charcoal adsorbent in rambutan rods has the ability to purify the water contaminated by metal ions.

This research was conducted to find out the effect of ab mix nutrient on growth and yield of Pak choi (Brassica chinensis L.) plants under hydroponic wick system condition. The research design used was non factorial Complete Randomized Design (CRD) with 5 levels of ab mix nutrient concentrations (0, 650, 1300, 1950, 2600 ppm), with 3 replications in each treatment. Each repetition consists of 6 plants, making a total 90 experimental units. The parameters observed were plant’s height, number of leaves, leaves area, fresh and dry weight, harvest index, leaf chlorophyll content, and root volume. Data was analyzed by using one way ANOVA, and DMRT as follow up. Research result shows that in hydroponic wick system ab mix nutrient gave very significant effect on pak choi (Brassica chinensis L.) parameters, such as: 1) plant’s height, 2) number of leaves, 3) leaves area, 4) dry weight 5) harvest index, and significantly effect on 6) fresh weight. However, it did not gave significant effect on root volume. The best results for each parameters observed were: number of leaves was 18.78, leaves area was 47.32 cm2, fresh weight was 33.57 gr, dry weight was 2.40 gr and harvest index was 99.15%, all were obtained from ab mix 1950 ppm treatment. The best results for plant height parameter was 8.71 cm obtained from ab mix 2600 ppm treatment.

Orchids are plants that has aesthetic value and high economic important. Included to ornamental plant whose existence is diminishing and endangered. To preserve this plant, it needs to in vitro thchnique. The aim of this study was to determine the best interaction of growth regulator Benzyl amino purine, coconut water and the interaction of both multiplication of Dendrobium sp. The research method used a completely randome design with various concentrations of Benzyl amino purine (BAP; 0,1,2,3 mg/L) and coconut water concentrations (0%,5%,10%). The parameter observation are number of buds, leaves and roots. The data were analyzed descriptively and inferentially with ANOVA. The results shows the real effect of BAP interaction, between coconut water buds and leaves, but did not significantly affect the number of roots. Within 12 weeks of observation the highest number of buds and leaf obtained from a combination of 5% coconut water + BAP 0 mg/L were 12.00 and 5.00. The lowest number of buds and leaves was obtained in combination of 5% coconut water + BAP 2 mg/L, 6.00 and 1.00.

Pineapple (Ananascomosus L.) from Sipahutar is an herbaceous plant from Sipahutar District. Pineapple is canning industry sourced from Sipahutar pineapple has the opportunity to be developed in North Sumatra. Propagation through in vitro culture is an alternative method to solve this problem. The purpose of this research was to determine the regeneration ability of pineapple callus derived from callus induction with the addition of 2,4-D 1 ppm and BAP 1 ppm. The callus were regenerated using the addition of Kinetin (0; 0.5; 1; 1.5 ppm). Each treatment was carried out 4 times. The results showed: 1) the fastest time of emergence of shoots (5 days) came from 0.5 ppm, 2) formed the most shoots (8 shoots) resulting from the addition 0 ppm and 0.5 ppm, 3) the most number of leaves (7.75 leaves) resulted from light treatment with the addition kinetin 0.5 ppm and 1 ppm, 4) the longest leaf length (4.44 cm) from dark treatment with kinetin 0.5 ppm, 5) the highest plant height (5.32 cm) from dark treatment with 0.5 ppm kinetin. This shows that the concentration of 0.5 ppm kinetin with the dark treatment is the best concentration to stimulate the formation of pineapple shoots.

The use of food ingredients to various processed products of livestock, agriculture, and fisheries requires a thickening agent to improve its quality. Salacca trees are found around the South Tapanuli Region. So there will be a study of its potential as a thickening agent. This research was conducted in April - June 2019 in South Tapanuli. The purpose of this study was to determine the quality of salacca tree midrib flour as a food thickening agent. This research shows that salacca tree latex flour has a fairly good quality and has the potential to be used as a food thickening agent.

On 2 March 2020, the Indonesian government, through President Joko ‘Jokowi’ Widodo, announced the first two cases of COVID-19 in Indonesia. This is the first case of COVID-19 officially confirmed in that country. Several cases have continued to increase since then. President Jokowi began issuing policies on the spread of this virus. This is different from other countries, such as Malaysia and Singapore, which responded from the previous month when the Indonesian government still stated that coronavirus does not exist in Indonesia. Our case study is to find a public opinion through social network analysis of Indonesian public policy during the beginning of the Indonesian COVID-19 pandemic in March 2020. This research implements text mining and document-based sentiments on Twitter data that is reprocessed through machine learning techniques using the Naïve Bayes method. We found negative opinions in the period more dominant by 46%, while that was 35% positive sentiment and 20% neutral. This research shows that anticipation, sadness, and anger are very dominant in the emotional analysis.

Long Term Evolution (LTE) the fourth generation (4G) cellular network technology. This LTE speed in data transfer speed reaching 100 Mbps on the side downlink and 50 Mbps on the uplink side. Growth in the number of service users telecommunication in Medan City causes a decrease in network quality, especially 4G LTE technology. By doing a driving test, the area can be found where a system’s signal strength aims to increase the signal quality. Benchmark (comparison) of operator service quality 4G LTE is done by measuring, comparing, and analyzing network quality (performance) of two 4G LTE operators around Muhammadiyah University of North Sumatra. Total operator throughput value X is only 0 > 3 Mbps while the Y operator is 0 > 30 Mbps. The low throughput value is caused by high user traffic during the day. The incidence of low throughput on the Muhammadiyah University of North Sumatra campus coincides with active learning with many students using data services.

Aedes aegypti mosquito is one of common vectors for the pathogens of different diseases like dengue hemmorrhagic fever. The most common approach to vector-borne disease is by chemical control, mostly through the use of insecticides. As compared to synthetic pesticides, essential oils (EOs) are ecologically safe, have no mammalian toxicity or the chances of development of resistance are reasonable and highly popular with the organic growers. This research has studied the larvacidal activity of essential oil from orange (Citrus sinesis L. Obbeck) and lemongrass (Cymbopogon nardus L. Rendle). Orange and lemongrass cleaned and cut into small pieces, dried and then blended to obtain crude drug samples. Samples distilled with the Stahl distillation method for 4 hours. Furthermore, terpenoids phytochemical test and test against larvae of Aedes aegypti larvicides to obtain the LC50 value. The yield of essential oil of orange (Citrus sinensis L Obbeck) obtained is 6.84%, while the essential oils of lemongrass (Cymbopogon nardus L. Rendle) was 0.96%. In the phytochemical test essential oils either of orange peel and lemongrass showed terpenoids. From the GCMS data, an essential oil from orange and lemongrass contain citronellal and limonene. Citronellal compound acts as an insecticide ingredient that works as an antifeedant and repellent. An essential oil from orange and lemongrass are toxic, with LC50 values obtained from lemongrass 35.133 ppm is smaller than the orange is 790.935 ppm. The essential oil of lemongrass more toxic than the essential oil of orange. Both of essential oils can be used as a green pesticide candidates.

The repeated use of cooking oil will cause the oil to be damaged by oxidation during the frying process. Thus, it is not good for health if it is continuously consumed. The purpose of this study was to determine the quality standard of cooking oil that was used repeatedly by testing the amount of peroxide, free fatty acids, and water content within the SNI 01-3741-2013 limits. The research was carried out 25 times of frying, at a temperature of 180°C, and a time of 7.5 minutes on red potatoes using a deep fryer. The result of the peroxide number test before frying was 5.24 mek O2/kg, and there was damage in the 11th frying pan with a value of 10.99 mek O2/kg. While the free fatty acids before frying are 0.16 mg KOH/g. and there was damage to the 19th pan, namely 0.64 mg KOH/g. the water content before frying is 0.14% b/b and the first cooking oil has met the SNI standard, namely 0.15% b/b. So it is known that the more frequent frying is done, the quality of cooking oil will decrease and will be carcinogenic.

Online learning has long been promoted by the Faculty of Mathematics and Natural Sciences (FMNS), State University of Medan (SUM). The online learning system (SIPDA) has been developed by Unimed as the backbone of online learning, but the number of lecturers using the system has not been as expected. The covid-19 has succeeded in forcing all lecturers to migrate from classroom face-to-face (offline) to online learning. This research was aimed to study the preferences of lecturers for available online learning media during the Covid-19 pandemic. The data were obtained using questionnaire that distributed online to all lecturers and students who were active in lectures for the even semester of the 2019/2020 academic year. The data shows that all lecturers have implemented online learning to serve all classes. The majority of lecturers serve their class by using more than one online media. The order of the three types of online media which became the main preference of lecturers experienced a shift during the 3 months of observation, namely from WhatsApp (WA) - Email - Google Classroom (GC) in the first, to WA - GC - SIPDA in the second, and to WA - SIPDA - GC in the third month. It can be concluded that, although initially the lecturers’ main preference in learning was social media (WA), they have tried hard to make SIPDA as the main choice among the available e-learning media.

One of the important parts of an electric furnace is the combustion chamber which is used to heat or melt materials. The chamber system which is based on the refractory, element, Rockwool, insulator, and Hebel (RERIH) has been successfully designed to reach high temperatures up to 1200°C. The refractory layer is designed from a mixture of trimortar cement and water. To obtain one side of the refractory, the composition of trimortar cement used is 2 kg mixed with 1 liter of water. The number of refractory sides needed for the electric furnace chamber is six sides, each of which is placed on the front, back, top, bottom, left side, and right side. To retain heat in the chamber, the refractory is covered with heat-resistant ceramic fibers (Rockwool). The Rockwool used has a density of 160 Kg / m3 and a thermal conductivity of 0.23 W / m.K. The maximum temperature that this Rockwool can withstand is 1260°C. The third layer as a heat barrier in the chamber is an insulator, which is a lightweight brick block made of a mixture of alumina. This refractory thermal insulation brick contains more than 48% alumina oxide so it has lower thermal conductivity and better heat insulation qualities. Meanwhile, the last layer is the placement of Hebel or light cement blocks made from lime which is usually used for building walls. This Hebel has dimensions (w x w x h) of 600 x 200 x 100 mm3.

The purpose of this study was to determine the effectiveness of the application of research-based tissue culture textbooks based on the critical thinking skills of students at Universitas Negeri Medan. This type of research was a quasi-experimental study using a pre-test and post-test control group design. The population of this study were all students of the Department of Biology class of 2015. The research sample consisted of two randomly selected classes. In the experimental class, the learning used a research-based tissue culture textbook and the control class used conventional textbooks. The results showed that the research-based tissue culture textbook that had been developed was effective based on critical thinking skills (Z = 1.301 and P = 0.000). The improvement of students’ critical thinking skills (N-Gain score) was 0.47 in the moderate improvement category. Therefore, it can be concluded that the research-based tissue culture textbooks were developed effectively based on students’ critical thinking skills.

Sub-maximal exercise also induces changes in the exercise of pro-inflammatory cytokine cell components such as TNF-α (Tumor Necrosis Factor-α).The purpose of this study was to determine the effect of red dragon fruit administration on changes in pro-inflammatory cytokines Tumor Necrosis Factor-α (TNF-α) after sub-maximal exercise. The research was carried out at the Faculty of Sport Science, State University of Medan. This study used experimental pretest and posttest group design. The research sample was twenty students divided into two groups. Group A: given sub-maximal exercise and placebo; Group B: received sub-maximal exercise and red dragon fruit. Sub-maximal exercise is conducted running on a treadmill with a sub-maximal intensity, a frequency of three times a week, lasting four weeks. The TNF-a examination was initially carried out at the end of the treatment and then evaluated in the laboratory using the ELISA method. The results showed a significant decrease in TNF-α levels after exercise in the sub-maximal exercise group given red dragon fruit compared to the sub-maximal exercise group given a placebo. The statistical results of the unpaired t-test showed that there was a significant effect of red dragon fruit on decreasing TNF-α levels after sub-maximal exercise. The conclusion is that red dragon fruit significant effect on decreasing TNF-α levels triggered by sub-maximal exercise in students.

This paper presents the convergence behavior of Discrete Kirchhoff Mindlin Triangular (DKMT) element in buckling analysis under uniaxial compression of square plate problems. The DKMT element has a good result for a thin plate and a thick plate. For the Functionally Graded Material (FGM) problem, the DKMT element is reformulated. FGM is a graded composite material that has high-temperature and structural flexibility resistance. The numerical results of mechanical buckling of square FGM plate under uniaxial compression using the DKMT element are reported. The critical buckling of the square FGM plate is compared to the reference existing solutions. The effects of parametric variation, such as the type of meshing, boundary conditions, power-law index, and ratio L/h are presented. The results show that the DKMT element gives good results on the buckling analysis of square FGM plate problems.