bluuebunny/crossref_metadata_2025 huggingface dataset:
Strength of structural elements with cracks
Authors: Peregudov A A , Vologzhanina S A , Igolkin A F
Published: May 2020

In almost every detail, despite careful control at all stages of production, there may be cracks. The reasons for their occurrence can be very different, including the shape and size of the part, the conditions and nature of loading, the nature of the environment, defects of a crystal lattice, the possible presence of non-metallic inclusions adverse forms, structure and grain size, depending on the technology upstream processing, fatigue, etc. The reliability of the equipment is determined by the correct choice of material and taking into account the operating conditions, including the level and nature of loading. The paper provides a comparative review of the main approaches for selecting strength criteria for structural elements with cracks. The energy and power strength criteria are considered. The energy criterion of A. A. Griffiths considered a perfectly brittle material without taking into account the plasticity reserve of real metal materials. The force criterion allows us to estimate the value of the stress taking into account the critical moment of loading, at which unstable destruction begins due to the reserve of elastic energy. It is shown that the transition of steel from a plastic state to a brittle one is influenced by the test temperature, the type and speed of deformation, and changes in the chemical composition and mode of heat treatment. Thus, when choosing a certain strength criterion, you should take into account the operating conditions and the degree of responsibility of the structure.
Numerical analysis of the heat flux density of the whole-body cryotherapy (WBC) object coming from the skin
Authors: Yerezhep D , Minikaev A , Zhignovskaia D , Pronin V , Yerezhep A
Published: May 2020

In technologies of cryotherapeutic effects, the main attention is paid to the choice of temperature of cryogenic gas. At the same time, along with the gas temperature, other process parameters are also essential: the gas velocity, the dimensions and spatial orientation of the biological cooling object, the humidity and gas velocity, etc. To develop the technique and technology of general cryotherapy, generalizing research is needed that can form the theoretical basis for the production and design of cryotherapy equipment. The most general results can be obtained by studying the effect that cooling has on a biological object with different intensities of heat removal along the length of the biological object. The work will conduct a chilled analysis of heat flux losses from the surface of the skin of a biological object with a slight change in the geometry of cryosauna during the whole-body cryotherapy process (WBC). To implement these tasks, a software package using the finite element method will be used. To describe the biological object with internal heat release, these biological heat equations were solved using the Penns approximation. The results of this work will help to give recommendations to cryosauna manufacturers to optimize the design of the cryotherapy unit, which in turn will help to increase the effectiveness of cryotherapy.
Power interactions of scroll compressor elements
Authors: Minikaev A , Yerezhep D , Zhignovskaia D , Pronin V , Kovanov A
Published: May 2020

The subject of our research is a scroll compressor. With its large number of advantages over reciprocating compressors in the form of overall, mass and production characteristics, they have their own difficulties associated with the theory of stability of a movable scroll during the operation process. As you know, a complex system of forces acts on the spiral, is very variable in magnitude and direction, for the period of one orbital revolution of the spiral. It should be noted that in modern designs of scroll compressors in the axial direction, a movable scroll has most often a one-sided rigid support - a thrust bearing. Moving the movable spiral in the opposite direction is limited only by the force of the gas axial pressure, which does not guarantee it saving its original position, at least within the gaps, touching the movable and stationary spirals, which is unacceptable. Next, we consider the basic calculation equations associated with the stability of a moving spiral.
Innovative online technologies as a tool of qualified specialists training in the field of waste management
Authors: Kakabayev A A , Fakhrudenova I B , Kurmanbayeva A S , Yevloyeva A S , Saparbekova A A
Published: May 2020

The article discusses new technologies that are used in creating content for online training modules, as well as specific examples of using certain tools in the formation of courses for online modules in the field of waste management in the framework of the EduEnvi project. The article describes online tools that can be used for visualizing, structuring and systematizing of various types of information, such as describing the course structure, showing a list of topics, possible tasks, etc. The need for visualization and systematization of information becomes very important when it comes to online training, which requires developers to be an extremely clear and detailed presenting their educational material, teaches them to be more open and communicative. The article also contains information about the formats of work in the project which helps partners from five different countries to exchange experience, learn something new and develop online courses. These online courses will be the main result of the EduEnvi project.
Study of submicrocapsules structure stabilized by modified silica dioxide nanoparticles
Authors: Zh Mutaliyeva B , Tleuova A B , Madybekova G M , Kurmanbayeva A S
Published: May 2020

In this research the structures of Miglyol 812 submicrocapsules, stabilized by silica dioxide nanoparticles, modified by oleic acid, were studied. It was found that the size distribution of silica particles modified with oleic acid depends on the amount of oleic acid. There is a limit to the ratio of oleic acid to silica at modification of silica particles with oleic acid. Experimental results have shown that the optimal ratio of oleic acid to silica is in the range from 110−2 to 5 10−1. The use of silica particles modified with oleic acid allows to obtain an emulsion with a 30 % of oil phase, with an average size from 80-300 nm. Thus, modification of hydrophilic silica particles with surfactants such as oleic acid in order to make them more hydrophilic and able to be adsorbed at the oil / water interface can be used to prepare a stable Pickering emulsion. As a result the stable Pickering emulsions which can be used for encapsulation of various substances were obtained, and the use of microcapsules allows one to decrease their impact on environment and increase efficiency of usage.
Perspective of using the biological method for gaseous emissions cleaning in the food productions
Authors: Nazarova A V , Kurnikova N V , Molodkina N R , Yulmetova R F , Sergienko O I
Published: May 2020

The article considers the problem of contamination of exhaust gases of confectionery plant because of harmful substances and unpleasant odors. A confectionery production uses a wide range of aromatic substances. Moreover, despite the presence of operating air treatment facilities the specific smell of ambient air could be sensed. To identify the most powerful sources of odor emissions the organoleptic study was conducted. Also, with the help of olfactometric study of the sources of odor, the composition of the aromatic mixture with a predominant content of terpenes and benzaldehyde was revealed. Several methods of treatment of gases-air emissions were studied including biological, thermal and thermocatalytic. Among the biological ways of air treatment, three types have been considered: traditional biofilters, trickling biofilters and bio scrubbers. Bacteria that helps to decompose aromatic substances like benzaldehyde or some of the terpene series have been found. Additionally, the mechanism of transformation of odorous substances has been studied.
Study of the content of heavy metals in the berries of the Vaccinium genus in the background areas of the North-West of Russia
Authors: Dinkelaker N V , Semenova T S , Ulyanov N B , Didikov A E , Petrova O V , Moiseenko E N , Dinkelaker N F J , Sinelnikova N A
Published: May 2020

The study of heavy metal contamination of products of wild berries of the genus Vaccinium (blueberry, cowberry, cranberry), growing in intact forests in four regions of North-West Russia-Leningrad, Pskov, Novgorod and Vologda regions is carried out. It is established that the greatest accumulation in berries of all studied species is observed for zinc, chromium and manganese. At the same time, the excess of the maximum permissible concentrations was noted for other metals - lead and arsenic, the level of pollution was moderate. In relation to these pollutants, the most sensitive genus is cranberry. The most likely source is roads and logging activities. The obtained results indicate the need to control chemical contamination of food products of wild berries and to expand the range of controlled parameters, in particular, the establishment of maximum permissible concentrations for chromium and nickel due to their significant bioaccumulation in berries.
Extreme vibration increase of the heat transfer coefficient of short heat pipes
Authors: Seryakov AV , Konkin AV
Published: May 2020

The results of the heat transfer coefficient studies of the short linear heat pipes (HP’s) with a formed by the capillary-porous insert vapour channel in the Laval nozzle-liked form under high thermal loads and external vibrations are presented. Under high heat power loads the vaporization process in the capillary-porous evaporator and vapour propagation in the vapour channel acquires a pulsating character with a frequency of 400-500 Hz and the amplitude up to 103 Pa. For the first time it was experimentally detected that under external longitudinal vibration, attached to the HP’s body with an limited amplitude of 0.15 mm and frequency equal to the frequency of arising internal vapour pulsations, the HP’s heat transfer coefficient shows the resonance nature and increases by up to 20%. The increase in the heat transfer coefficient is due to the boiling process intensification in the grid HP’s capillary-porous evaporator.
Development of a fast method for forming Braille on the surface of steels with IR ns-pulsed 50 W fiber laser
Authors: Amiaga J V , Vologzhanina S A , Ermakov B S , Gorny S G
Published: May 2020

Convex linear structures of various configurations with a height of up to 200 microns and a depth of up to 100 microns, point structures with a height of up to 500 microns were obtained on the surface of the steel using a 50 W 1.064 μm wavelength fiber laser source. No additives were used. The structures were formed from the material of the irradiated steel by controlling the dynamics of the melt. The possibility of forming Braille on a steel surface using this technology is demonstrated. The results are encouraging for a number of industry sectors where electron beam machines and high-powered laser sources are cost prohibitive, and one need a high rate of obtaining relief.
Technological approaches to the quality management of bakery products
Authors: Fedotov V A
Published: May 2020

The article studies the influence of the physicochemical properties of wheat grain on the quality indicators of bakery products. Methodological approaches to managing the quality of bakery products through the development of production solutions have been formed by varying the technological parameters of the use of wheat flour (moisture of the leaven when the leaven method of dough preparation is used) taking into account its physicochemical properties (hardness of wheat grain). Wheat grain in a wide range of hardness - from low-hard to ultra-high-hard was studied. Regulated indicators of bread quality were the volume yield of bread and the integral characteristic of the organoleptic evaluation of bread on a 100-point scale. It is shown that the increase of grain hardness of flour and gain in moisture of starter dough (the average yield by weight of bread increases by 1% when the moisture of starter dough is 8 %) lead to increasing bread’s yield by weight. To simplify the model of forming the quality of bread depending on the grain hardness and humidity of the used starter dough, a constant value of the specific work when dough kneading was used. Regression equations for the formation of white bread quality indicators with a high degree of confidence (determination coefficient 0.72-0.89) and corresponding bread quality nomograms are constructed.
Comparative analysis of elasticity and rigidity of morphological parts of wheat grain
Authors: Fedotov V A , Yu Solovykh S
Published: May 2020

The article presents the results of a comparative assessment of the elasticity and rigidity of various morphological elements of wheat grain depending on the nature of the grain (normal, frosted, after drying, after scouring machines). The dependences of the rigidity of wheat grain on the structure, chemical composition and humidity are described. A close correlation was revealed between the structural and mechanical properties of wheat, assessed by microhardness, strength index, and the results of laboratory and industrial grinding of wheat grains of various consistencies. For different consistency of wheat grain, microhardness was determined using the microhardometer “Miniload”, and the strength index was determined using the Brabender’s hardness tester. At relatively low stresses, the shells have flexural elasticity. IT was detected that with increasing humidity, the rigidity of the shells during bending decreases. It was found that for hard and hard-grained varieties of soft wheat, the compression force is required 2-4 times more than for soft-grained varieties. It is shown that the microhardness of glassy grains of hard-grained and soft-grained wheat varieties is basically at the same level. At the same time, with increasing humidity, the microhardness of the grain decreases regardless of the variety, area of growth and vitrescence of wheat.
Thermodynamic cycle of lithium bromide absorption chillers with two-level absorption and generation processes and with associated mass flow
Authors: Malinina O S , Kasyanov A V , Baranenko A V
Published: May 2020

The paper presents the assessment of the energy efficiency of the thermodynamic cycle of the absorption lithium bromide refrigeration unit with two-level absorption and generation processes with the associated mass flow. The analysis of temperature effect of heating and cooling sources on thermal coefficient is carried out. The parameters of external sources when it is possible to determine the energy efficiency of the thermodynamic cycle are defined.
Calculation of cold accumulators with phase change materials
Authors: Yu Zakharova V , Kuznetsov P A , Baranenko A V , Faizullin R O
Published: May 2020

The paper presents an improved technique (mathematical model) for numerical calculations of solid-liquid phase transitions based on a zero-dimensional solution of the Stefan problem for cases of placing phase change materials in ball-shaped or cylindrical capsules. According to the proposed model, numerical calculations of the liquid phase volume fraction in Scilab have good compliance with experimental data for n-octadecane, and the calculation time is reduced several hundred-fold in comparison with calculations in Fluent.
Results of temperature effect on thermo-physical properties of guava fruit of Southeast Asia
Authors: Tun A , Baranov I V , Krylov V A , Tambulatova E V
Published: May 2020

The research presents the results of the effect of temperature on thermo-physical properties of guava fruit of Southeast Asia. Guava is an energetic fruit with high nutritional value and is considered a tropical fruit of South-east Asia. Fruit growers need to use cold storage facilities to extend the revenue period while maintaining produce quality and freshness. The storage life of fresh fruits can be extended by several days by cooling. The specific heat of foods can be used to calculate the refrigeration load calculation. Therefore, the specific heat of food plays an important role in the design of storage and transport systems. One of the most important thermo-physical properties in foods are specific heat. The authors of the article used differential scanning calorimetry (DSC 204 F1), by which the specific heat of guava fruit was determined in the temperature range from –25 to 25 °C. It was found that the specific heat of guava fruit is dependent on temperature.
Performance of FRC and GPC for High-Rise Construction: Case Studies
Authors: Gharehbaghi Koorosh , Rahmani Farshid , Paterno David , Gharehbaghi Sara
Published: May 2020

This paper aims to compare Fiber Reinforced Concrete (FRC) and Geo-Polymer Concrete (GPC) for high-rise construction. In doing so, 8 case studies from the USA and Australia are reviewed. The ever-increasing use of material processing linked to environmental degradation has encouraged industries to seek alternative materials. Both FRC and GPC are examples of such alternative materials. Their composition of these materials is derived from manufacturing, building and construction excess. Concerns remain, however, regarding these material’s abilities such as strength, when compared to the traditional i.e. concrete, steel etc. This paper reviews select case studies where FRC and GPC materials have been used. In addition, their overall structural integrity was also observed. This paper then scrutinized their Structural Health Monitoring (SHM) to uncover their specific structural performance. Subsequently, this paper found that for both FRC and GPC extreme weathering conditions may affect their structural performance. Finally, case study review also indicates additional comprehensive research is required to review such relationship.
Mechanical and Post-Cracking Performance of Recycled Aggregate Concrete Incorporating Synthetic Fibers
Authors: Kazmi Syed M S , Munir Muhammad J , Wu Yufei , Patnaikuni Indubhushan
Published: May 2020

Reuse of concrete waste in novel construction is becoming very important topic nowadays. This study focuses to examine the post-cracking and mechanical performance, fracture behavior, and micro-structure of fiber strengthened recycled aggregate concrete (RAC). For this purpose, crack mouth opening diameter (CMOD) tests were conducted on twenty-seven notched beam specimens (550 × 150 × 150 mm) having three replacement levels (i.e., 0, 50 and 100%) of recycled concrete aggregates (RCA) and three synthetic fiber dosages (i.e., 0, 0.5 and 1%). Different mechanical properties of all mixes were also examined following ASTM standards. Drop in the mechanical performance of RAC was noticed at higher RCA replacement levels. However, synthetic fiber reinforced RAC showed better performance as compared to plain RAC. Results also depict positive influence of synthetic fiber addition on the residual flexural tensile strength of concrete. Approximately, 129% and 380% rise in toughness index and fracture energy was also observed for 1% fiber incorporation in RAC. Moreover, scanning electron microscopic analysis also confirmed the synthetic fiber-mortar bond. Therefore, synthetic fibers enhance the post-cracking and mechanical performance of fiber reinforced RAC resulting into more ductile and energy absorbing sustainable concrete.
Feasibility of PET Resin as a Cement Substitute for Sustainable Construction
Authors: Patil Y D , Waysal S M , Dholakiya B Z
Published: May 2020

Polyethylene Terephthalate (PET) is one of the most widely used plastics in the packaging industry. PET need hundreds of years to decompose. There is an increasing demand for cement in the construction industry. If we could use PET in construction, it will be an excellent relief for the environment.

In this study, PET bottles were used to produce a PET resin by glycolysis in polyethylene glycol. These resins were prepared for a different proportion of PET particles and were added in 5, 10, and 15 percent by mass of cement. The effect of this resin on standard consistency, setting time, together with slump flow and compressive strength of cement paste, is studied. It is observed that the addition of PET resin alters the standard consistency and compressive strength, increases the setting time and slump flow. The findings of this study suggest that PET waste can be utilized to replace cement.
Evaluation of Acoustic Environment of High-Rise Residential Space
Authors: Cheng Yumeng
Published: May 2020

As the most common type of urban residential form, high-rise residential space is the main place for people’s leisure and entertainment, so its acoustic environment quality is very important. In this paper, the acoustic environment of typical high-rise residential space is measured and analyzed, and survey questionnaires are statistically analyzed to explore the influence of listener’s behavioural factors and social factors on the perception of soundscape. In order to provide reference for related design and management work. The results show that behavior factor such as activity frequency, time, location and social factors such as sex and age was associated with soundscape evaluation significantly.
Evaluation of Mechanical Hardened Properties of Mortar Using Carbon-Free Fly Ash and Normal Fly Ash
Authors: Nazari Ghawsaddin , Takayuki Sato , Date Shigeyuki
Published: May 2020

Usage of mineral admixture and chemical admixture in concrete or mortar is a usual solution to reach full compaction, particularly where reinforcement blockage and lack of skilled labour happen. In this paper effect of mineral admixtures (Carbon-free fly ash, hereafter CfFA, and nFA) on hardened properties of mortar such as compressive strength, Pore size distribution and, and micro structures have been investigated. As a result, it has been confirmed that mortar containing 15% CfFA slightly increased the compressive strength under water curing condition compared to those containing 15% normal fly ash. In addition, the pore-size distribution of the mortar has been affected by variation of materials and curing condition. Mortar containing 30% CfFA had a smaller threshold diameter in comparison to that of 30% FA; however, there is no significance differences in mortar containing 15% CfFA and FA. Furthermore, CfFA-based mortar increased the amount of entrained air compared to the mortar with normal fly ash.
An Alternative Technique for Accelerated Carbonation of Normal Concrete
Authors: Ramesh Bura Akshay , Kondraivendhan B.
Published: May 2020

Carbonation is a continuous process in concrete structures and taking place for large period of time. The present study investigates accelerated carbonation effect on normal concrete with the help of Ammonium Bicarbonate (NH4HCO3) solution. Normal concrete specimens were exposed to carbonated water curing for different durations after initial 28 days of normal water curing. The effect of carbonated water curing on concrete specimens was studied with the help of compressive strength test and pH profiling test. From the results, it was observed that the compressive strength of normal concrete specimens increased and pH value increased along the depth from the surface with prolonged carbonated water curing.
Blast Mitigation Effects on Facade System with Projections Utilizing Fluid-Structure-Fluid Interaction
Authors: Patel Deepam , Desai Atul K
Published: May 2020

Various studies have been conducted on facade system exposed to blast loading have been explored in various studies. Studies conducted are limited to interaction between the fluid and solid domain neglecting the coupling effects of both domains. The impact upon interacting with a free standing will cause the structure to displace its position in the direction of the impact which will decrease the impact upon the structure. At the same time, the impact induced behind the structure will further reduce the effect of impact. This impact generated will marginally counteract the reduction of pressure on the structure. The displacement of the structure as well as shock-wave generated play a major role in reduction of impact on stationary structure. The effects of stress propagation within the structure have been ignored.
Research on the Influence of Variable Stiffness Levelling Piles on Differential Settlement of High-rise Buildings
Authors: Yang Yufeng , Gan Tengjun
Published: May 2020

Due to the differential settlement of the piled raft foundation of high-rise buildings and super high-rise buildings, secondary stresses will be generated in the superstructure, and variable stiffness leveling can solve this problem. However, different methods of laying piles may cause large differences in the amount of piles used and the bearing capacity of the foundation. In order to explore the effects of different combinations on differential settlement and internal forces, this article studies the upper structure and foundation as a whole, using finite element software ABAQUS, calculation and analysis of piled raft foundations under self-weight and lateral loads. The effects of different pile lengths, different pile diameters, dense piles, and different pile lengths and different pile diameters on the different settlements and internal forces are analyzed. The research found that the variable pile length form has the best effect on the control of differential settlement, followed by the variable pile pitch type, and the effect of the variable pile diameter, the combination of variable pile length and variable pile diameter is poor. The research results can guide the design unit’s design of pile distribution, and maximize the economy and safety.
Analysis of instruments and mathematical disposition using Rasch model
Authors: Suhaedi D , Fajar M Y , Sukarsih I , Permanasari Y
Published: May 2020

The purpose of this study is to analyze the instruments and mathematical dispositions of students. The instrument consisted of 22 items of mathematical disposition statements. Instrument testing was conducted on 18 private vocational students consisting of 6 males and 12 females. Analysis of the instruments and students’ mathematical dispositions was carried out using the Rasch model. The aspects analyzed consisted of mathematical disposition instruments, students ‘mathematical disposition abilities, the interaction between the instruments and students’ abilities of mathematical dispositions, and instrument quality. The results of the analysis of mathematical disposition instruments show that there are four items of instruments with difficult categories, thirteen items with medium categories, and five items with easy categories. Generally, the ability of students’ mathematical disposition is still low, compared to the demands of instrument difficulty. The interaction between instruments and students’ mathematical disposition abilities is very good. The consistency of answers from students is good, and the quality of the mathematical disposition instruments is sufficient.
Bus schedule modelling in Bandung, Indonesia, using max-plus algebra
Authors: Sugiarto I , Permana F J , Yosep A
Published: May 2020

Congestion has been a big problem in many big cities in the developing countries. One of the main factors causing traffic congestion is the lack of use of public transportations. The network problems related to synchronization problems, e.g. scheduling of public transportation, can be modeled and solved using the Max-plus algebra. Bandung as the capital and the biggest city in the West Java has also faced such a problem, that is congestion. In this paper, the scheduling of DAMRI bus, one of public transportation in Bandung will be modelled using the Max-plus algebra. We choose two DAMRI routes in Bandung, those are Dipatiukur - Leuwi Panjang and Ledeng - Leuwi Panjang. Both routes are transformed into a directed graph with the bus stops as the nodes. The Max-plus algebra is applied to develop the bus scheduling. In the developed model, the eigenvalues and eigenvectors of the system are calculated. The eigenvalues represent the period of departure at each bus stops and the eigenvectors represent the initial time of departure of the DAMRI bus. The results show that for every 3.7492308 minutes a bus will depart at each bus stop. If the DAMRI bus operation starts at 05.00, then the first departure should be from the bus stop in Pasir Kaliki to the bus stop in Hasan Sadikin Hospital.
Bearing degradation prediction based on support vector regression
Authors: Darwis S , Hajarisman N , Suliadi S , Widodo A
Published: May 2020

Predicting bearing degradation before reaching the state of risk of accident is one important issues in power generation insurance. This paper proposes a method based on support vector regression to achieve the goal. The method is applied on PRONOSTIA dataset which is an experimental platform dedicated to test methods related to bearing health assessment. The results show that the method can effectively model the evolution of the bearing degradation.
Techno-economic assessment for optimal electricity and diesel fuel production using corncob gasification–Fischer Tropsch process
Authors: Yulistiani F , Wachjoe C K
Published: May 2020

Biomass gasification technology has been developed in Indonesia in the last 30 years. However, the use of synthetic gas directly on diesel engine and steam turbine for electricity generation has a relatively low efficiency. New technology has been emerged to integrate thermal gasification with Fischer-Tropsch (FT) synthesis which then can be combined with heat and electricity production. This paper consists of techno-economic study for optimal electricity and diesel fuel production using corncob gasification integrated with FT process. Optimal production (409 GWh electricity, 58,900 kL fuel) can be achieved when using air and operating pressure 25 bar. Calculated production cost is 6,569 IDR/kL FT fuel and 245 IDR/kWh electricity. With average Indonesian electricity tariff 1,123 IDR/kWh, BGFT electricity production cost is much lower, about 22% of Indonesian electricity tariff. Corncob price change has higher effect on electricity production cost than water price change. So, if the electricity cost wants to be hold in economic level, then the corncob price should be held constant. The price will stay constant if there are no competitor that would use corncob as raw material. As of now, corncob still considered as waste that are not used for economic activities.
The influence size and composition of bioreactor from sand and compost to improve hold up liquid of bed
Authors: Fauzan A , Rispiandi R
Published: May 2020

Increasing population in Bandung will cause the need for products from plants also increase, while the available land decreases so that it is necessary to intensify the process in agriculture. One of them is by making plant bioreactors that can facilitate availability of water and nutrients in the land. The purpose of this study is to obtain the influence of bed variations on hold up liquid parameters of a bed. The tests included hold up liquid tests of various bed variations consisting of variations in size (not sieved; 4 - 2 mm; 2 - 1 mm; 1 mm - 500 μm; 500 - 250 μm and 250 - 125 μm) and composition variations (100 : 0; 25:75; 50:50; 75:25 and 0: 100) from compost and sand in order to get a good ratio of bed between sand and compost on hold up liquid in the soil. The total sample obtained is 30 samples. Based on the experimental results, it was concluded that the sand and compost with a ratio of 25: 75 and diameter of 500 - 250 μm as a good composition to increasing the holdup liquid value of bed with 0.3 hold up liquid.
Thermal design of cooler in the fuel handling pneumatic system of RDE
Authors: Dibyo S , Irianto I D , Bakhri S , Pancoko M
Published: May 2020

A small size reactor called Reaktor Daya Eksperimen (RDE) is being designed by BATAN. The nuclear reactor with the power of 10 MWt based on the High Temperature Gas-Cooled Reactor (HTGR) type. The helium gas with high temperature is used to remove the heat generated from the reactor core. Therefore, the helium gas as primary cooling system of reactor is high temperature. The typical of reactor cooling system is that the primary coolant system pressure should be lower than the secondary coolant pressure. In order to load a nuclear fuel pebble into the reactor core, a fuel handling system (FHS) is applied. In the FHS, a carrier gas of pneumatic system is important to blow the fuel pebbles. The objective of the research is to calculate the thermal design of cooler heat exchanger in which the high temperature of helium gas as carrier gas is reduced to be lower temperature. In this case, a cooler is used to cool the helium gas by coolant water. Based on the specification data requirement to calculate the thermal design of cooler, the ChemCAD.6.1.4 software was performed. A shell-tube type of heat exchanger has been determined to reduce the temperature of helium gas from 250°C to be less than 60°C at pressure of 30 bars. The water as a coolant is passed into the shell-side at temperature of 28°C. In the design calculation, it has carried out through a various consideration on aspects of safety as well as optimization. The result of thermal design are as follows: the heat exchanger of shell-tube type using fixed tube sheet with heat duty of 0.3122 MJ/s, the coolant water mass flow rate is 3.55 kg/s, surface area for heat transfer is 51.4471 m2 and Log Mean Temperature Difference (LMTD) is 81.53°C. Furthermore, the design result requirement of heat exchanger based on the specification, design tolerance and manufacture in appropriate with the TEMA standard of shell-tube type. The thermal design of cooler in the carrier gas of pneumatic system is expected to provide the design of FHS.
Effect of bean maturity and roasting temperature on chemical content of robusta coffee
Authors: Wahyuni N L E , Rispiandi R , Hariyadi T
Published: May 2020

This study aims to determine the effect of roasting temperature on chemical content of coffee beans at various fruit maturity. Robusta coffee was obtained from Karawang Regency, West Java. After picking, sortation, and drying in the sun to 10% moisture content, the coffee beans were roasted at 190°C, 200°C, 210°C for 12 minutes. Physical properties observed were weight loss during the roasting. The chemical content observed were water, caffeine, fat, chlorogenic acid and ash before and after roasting. Chemical content analysis was performed using gravimetric methods, soxhlet extraction, and UV-Vis spectrophotometry. The color, aroma and flavor of roasted bean were conducted by organoleptic test. The results obtained, the ripe coffee bean with roasting temperature of 210°C is the best, which gives the lowest yield. The unripe green beans have the highest water content. The roasting temperature did not provide a significant difference in fat, caffeine, chlorogenic acid, and ash content. Organoleptic test results (color and aroma) showed that the mature beans with roasting temperature of 200-210°C were the most preferred, while the coffee brew most preferred was overripe bean with the roasting temperature of 200°C.
Breakthrough curve investigation for analysing effectiveness of CO2 adsorption using K2CO3 in fixed bed column
Authors: Elizabeth L , Heriyanto H , Immah H , Aqshanrilyan K
Published: May 2020

Carbon dioxide contributed great amount of Green House Gas (GHG) emission. Solid adsorption is one of the way to ease or lower carbon dioxide emission. The objective of this study is investigating breakthrough curve of CO2 adsorption using K2CO3 solid in fixed bed column. Adsorption experiment is used to analysed adsorption capacity, breakpoint time and length of effective bed height. K2CO3 used as adsorbent and rice husk as support. The K2CO3 adsorption occurred under mild condition. The CO2 inlet and outlet concentration were analysed by acid-base titration. The highest adsorption capacity by K2CO3/rice husk is 0.2 mmol/g adsorbent at CO2 inlet flow rate 28 LPM (litre per minutes) by 50 gr K2CO3 adsorbent. it is necessary to vary other parameter because CO2 flow rate (15,9 and 28 LPM) and adsorbent amount (50-125 gr) do not affect adsorption capacity significantly.
Effects of pretreatments and different types of microbial starter on biogas production from food waste
Authors: Gantina T M , Wachjoe C K , Kurniasetiawati A S
Published: May 2020

The problem with the slow process of anaerobic biodegradation, especially in food waste, is that the rate of biogas production cannot keep up with market’s high demands for fuel. Several studies have tried out to optimize the rate of biogas formation, such as the addition of microbial starters and pretreatments. The objective of this research is to examine the production and characteristics of biogas made of vegetable market waste added by EM-4 and GP-7 microbial starter using a single batch biodigester system. The specific target is to determine the performance of biogas production process by combining the two techniques. The methods used consists of the design and manufacture of batch system biodigesters, determination of raw material characteristics, preparation of raw materials by pretreatment and addition of starters, namely EM-4 and GP-7. By combining the two techniques, biogas production with greater volumes and concentrations of methane gas can be obtained in a relatively short period. Pretreatment with NaOH 3% solution and the addition of cow dung starter and GP-7 can increase biogas production with the largest methane content on the 45th day and reached 38.32% of CH4 while pretreatment with NaOH with starter EM-4 and cow dung only reached 22.5%.
Sediment control analysis due to erosion and sediment in Cipunagara watershed, Indonesia, using SWAT model
Authors: Fitriyana E N , Supratman O , Mardiani M
Published: May 2020

Erosion and sediment are parameters that describe the critical level of a watershed. Cipunagara watershed is one of the most critical watershed in Indonesia. Therefore, we need a study of sediment control due to erosion and sediment. This study aims to determine the level of erosion in Cipunagara watershed, find out sediments in Cipunagara River, and determine the sediment control structure that can be applied in Cipunagara River. The method used in this research is quantitative descriptive method with modelling on SWAT. The analysis was performed using secondary data in 2005-2014. Modelling in SWAT divides Cipunagara watershed into 33 Sub Watersheds. The highest erosion value during years data occurred in Sub-watershed 18 of 654,402 tons/ha/year with very severe erosion criteria and the lowest in Sub-watershed 5 of 1,075 tons/ha/year with very mild erosion criteria. The highest sediment value is in River 25 which is 1754758.30 tons/year, and the lowest in River 7 which is 7174.40 tons/year. Sediment control in Cipunagara watershed can use check dams that place on River 18 and River 25.
Repairment of clay shale soil by stabilization method using a cement binder
Authors: Fathurrohman A M , Syahril S , Somantri A K
Published: May 2020

Clay shale is a type of clay that is easy to expand when it comes into contact with water because of the montmorillonite clay mineral it contains. The effect of water also causes a decrease in strength in the clay shale. As a result of the clay shale behavior, some buildings become damaged or landslides occur on the slope. The soil stabilization method with a cement binder is one solution to improve the detrimental properties of the clay shale. The selected cement content variations are 20, 30, and 40%. Cement Water Factor 35% for all variations. Laboratory testing is carried out at 0, 7, 14, and 21 days. Tests carried out in the form of specific gravity, swelling, atterberg limits, unconfined compressive, cation exchange capacity, X-Ray Difraction (XRD), and Scanning Electron Mycroscope (SEM). Tests show that the most optimum mixture is 30% clay shale-cement (CS-C30). CS-C30 produces changes in clay shale parameters including an increase in compressive strength without any decrease, and a reduction in the expansive nature as indicated by the decrease in the value of swelling pressure, and cation exchange capacity. Changes in these parameters are suspected because it already does not contain montmorillonite in CS-C30 based on XRD.
Comfort improvement of landscape and housekeeping components on government green building using Building Information Modeling (BIM) integrated web-based information system
Authors: Haolina G A , Latief Y , Machfudiyanto R A
Published: May 2020

The aim of building maintenance is to preserve the function, structure, and aesthetics of the building in accordance with the initial conditions. An ineffective building maintenance management leads to increased cost, reduced building reliability, and failure to achieve the green building mission. One problem highlighted is that building management are still using call-center system with no database to store building damage data. Therefore landscape and housekeeping components are damaged below the allowable standard and become no longer functional. The purpose of this study is to improve the maintenance performance on landscape and housekeeping components of government green buildings. The case study was the Ministry of Public Works and People’s Housing Republic of Indonesia. The research methods used are literature reviews, surveys, case studies, and expert judgement for validating content and construct. This study uses a Work Breakdown Structure (WBS) in managing data dynamically using Building Information Modelling (BIM), integrated with web-based information systems. The result is that using BIM-based website leads to a more effective and efficient maintenance, thus improving the maintenance performance especially comfort on landscape and housekeeping components. The most significant variable according to the coefficients model are infiltration well, trash bin, groundcover, carpet floor, and visualisation.
Information system development using BIM on wall work packages of government green building to improve the convenience of maintenance performance
Authors: Pratiwi Y S , Latief Y , Machfudiyanto R A
Published: May 2020

Comfort is one indicator in the performance of building maintenance. This performance can be achieved by carrying out maintenance work on the building architecture components. The maintenance of government green buildings in Indonesia has not been done in an optimum manner due to constraints in maintenance work to government green buildings such as non-digitized data, poorly documented data, substandard maintenance work, and poor or slow identification of damages. Impacts resulted from the poorly maintained building are the increasing operational cost and ineffective maintenance work done to the building. The aim of this study is to increase the comfort of maintenance performance of the architectural component of government green building, especially the wall work package. The case study taken is the Ministry of Public Works and Public Housing Building which is considered as a representation of government green building in Indonesia. The method used are literature research, case study, and survey. The result of this research is the information system development using Building Information Modelling (BIM) integrated into building maintenance systems such as Work Breakdown Structure (WBS), SOP, and building maintenance guidelines for architectural components.
Determining priority infrastructure provision for supporting agrotourism development using AHP method
Authors: Tonny J , Wulan P
Published: May 2020

Agrotourism is a tourism activity using agro-business since beginning to end agriculture products in any system, scale and form as tourism object, with aims to widening knowledge, traveling, recreation, and business relationship in agriculture. Infrastructure divided into hard infrastructures (such as transportation, irrigation, drainage, electric network, clean water piping, communication network, sewerage, and waste management); and soft infrastructures (such as government policy, finance, and insurance services, information and communication services, education services, health services, and travel service). This research aim is to show how to use AHP as a tool to make a decision determining priority infrastructure provision, in the preference to support agrotourism development. This research takes Karo Regency, North Sumatera, Indonesia as a case study that has agrotourism attraction spread almost at 17 subdistricts. This research also uses AHP (analytical hierarchy process) for decision making with comprehensive characteristics, to handle complicated problems, multi-attribute, qualitative and quantitative scope. As research results, a decision with preference to get the biggest benefit value in short time for local government, and for Karo Regency peoples, is getting priority provision to start by hard infrastructure in the form of clean water supply first, then providing soft infrastructure in the form of government policy.
Evaluation of the maturity level and critical success factors in the implementation of knowledge management in the national private construction service company in Indonesia
Authors: Zain A H , Latief Y
Published: May 2020

At present, knowledge management (KM) is considered an appropriate competitive tool for success in a knowledge-based economy, many organizations have deployed and implemented KM to improve performance. The purpose of this paper is to provide guidelines and picture for organizations to evaluate the level of KM maturity of national private construction service companies in Indonesia and ways to improve them so that organizational performance improves. The first step in achieving the KM goal is the recognition of the current status of the KM capability itself in the company gained through the KM maturity model. Next, how to improve it so that the company’s performance is better by reviewing alignment with identifying critical success factors (CSF). Seven organizational or functional criteria are used as key elements towards an effective KM approach, namely policies/strategies, HR planning and processes, training and improvement of human performance, procedure methods and documentation processes, technical solutions (IT), approaches to capture/use tacid knowledge, and KM culture. Based on the results of the study, it was concluded that the level of KM maturity was in the second level, namely the development stage. Policies/strategies are the main categories to be improved.
Re-designing vocational school technical drawing studio with 2 lightning system
Authors: Riyani F N , Maknun J , Yosita L
Published: May 2020

The more detail drawing product in the shop drawing, the more drawing concentration is needed. One of supporting drawing concentration factors is lightning quality, because of that human pupil very responsive to emitting light. This research is intended to Re-Design technical drawing studio 2 SMK N 2 Tasikmalaya lightning system to be suitable from lightning standard. The result from lightning analysis in technical drawing studio 2 was showing poor lightning quality because lack of lightning intensity, differences lightning distribution, and high glare potential. The condition of drawing concentration class X DPIB 2 SMKN 2 Tasikmalaya was different each work table. The work table which has high glare potential and inconsistency lightning involve poor concentration. The result from Re-Design lightning system both natural and artificial in technical drawing studio 2 SMK N 2 Tasikmalaya was made by adding opening in the southside, installing a double-skin façade, changing wall interior color, and changing luminaire type will increase technical drawing studio 2 lightning quality from lightning standard so does drawing concentration. The result simulation of Re-Design was showing better lightning quality such as the increase of lightning intensity from 269 lux to 937 lux and minimize glare potential in 11 work tables.