Bandung Institute of Technology
  • Bandung, West Java, Indonesia
Recent publications
Naturally-derived antidiabetic medications have been explored as alternatives to the current widely-used drugs which can cause mild to severe side effects. Sauropus androgynus has been traditionally utilized to treat diabetes patients. In this report, a flavonoid glycoside, astragalin (1), was isolated from the leaves extract of S. androgynus using bioassay-guided isolation approach. Enrichment processes using macroporous resins resulted in two enriched fractions with 1 contents of 0.083% and 0.054% for PAD610 and PAD900 fractions, respectively. Compound 1 showed a higher α-glucosidase inhibitory (IC50 = 55.03 ± 0.61 μg/mL) than that of acarbose. In vitro assay for antioxidant and α-glucosidase inhibitory activities showed the greatest inhibition by PAD 610 fractions which has 98.912% and 83.268%, respectively. These findings have shown promising results for further studies on S. androgynus as a potential herbal drug, particularly for the treatment of diabetes.
This paper deals with warranty cost analysis for a warranted product protected by lemon laws during the warranty period. The product is declared a lemon if either of two conditions are met: (i) the product has been returned to the dealer k (e.g. k = 4) times to have the failed product fixed, and the manufacturer was unable to repair the problem satisfactorily, or (ii) the product has been out of service more than the prespecified threshold (e.g. 30 days) due to one or more failures. We study two cases – (i) refund and (ii) replacement cases. For (i), if the product turns out to be a lemon then the manufacturer refund the purchase price, and replace with a new one for (ii). Since the complexity involved in the formulation of the expected warranty cost (EWC), a simulation approach is used to evaluate the EWC for the two cases considered. We give numerical examples to illustrate the EWC for refunding and replacement cases and discuss the impact of a reliability and/or quality improvement to reduce the EWC for the two cases.
The presence of non-condensable gases (NCGs) in a geothermal fluid disrupts the vacuum process in the condenser, reducing turbine efficiency and decreasing the total power output of the geothermal power plant (GPP). Therefore, to optimize the thermodynamic efficiency of a GPP, NCGs should be removed using a gas removal system. Since there is a substantial lack of design and simulation software for a GPP including NCG removal alternatives, in this study, we aimed to model and develop a software-based interface to simulate mass and energy balance involving an NCG fraction in a single-flash GPP as well as examine the thermodynamic performance of the gas removal system, which is the most important step in the planning and designing phase of a GPP. This software was validated using outputs of Kamojang GPP Units 2, 3, and 4 located at Kamojang geothermal field, Garut, West Java, Indonesia. Units 2 and 3 use two ejectors which are installed in series, and Unit 4 utilizes a hybrid system (HS) that is mostly a combination of vacuum pumps and a steam jet ejector (SJE). Our results showed that Kamojang GPP Units 2 and 3 generate 55.295 MW of power with an absolute error of 0.53%, whereas Unit 4 generates 60.218 MW of power with a 0.36% absolute error concerning the field data. These results correspond with the expected minimum error; therefore, our model’s parameters are considered valid and can be used for simulation. We found that using the simulation, the total steam saved by the HS at Kamojang GPP Units 2 and 3 was 534 kW. Furthermore, the net power production was reduced by 1.6% for the HS and 2.03% for the SJE with every 1% increase in the NCG fraction. The power requirement of the vacuum pumps remained less than the power generated by the motive steam which the ejector requires to dispose of the same amount of NCG, indicating that Kamojang GPP Units 2 and 3 will be more efficient if an HS is used.
The national electronic identity (e-ID) for citizen data verification has seen widespread use in the last several years, including in Indonesia, which has a specific card, namely “Kartu Tanda Penduduk Elektronik” (e-KTP). The e-KTP utilizes a contactless smart card type for the citizen’s proof of identity. However, due to the limited availability of compatible e-ID readers for cost reasons, e-ID utilization in Indonesia is not yet optimal, and its verification still needs to be done manually. As such, in this work, a prototype of a portable Android-assisted e-ID verification system is designed. This work aims to develop a portable e-ID reader that can be adopted for various fields in Indonesia. The proposed system contains two primary components: hardware to scan the e-ID card and verify the fingerprint and an Android app user interface to verify the signature and photo and display the verification result. The hardware consists of a CPU, contactless smart card reader module, secure access module, fingerprint sensor, power management unit, and a Bluetooth module to interact with the Android app. The hardware is powered using a lithium-ion battery to support the system’s portability. Meanwhile, the software consists of signature and photograph input and verification and operator logging. The hardware testing consists of several phases: battery durability test, hardware initialization, card reading, fingerprint verification, and application connectivity. The software testing involves photo and signature input, verification, and operator logging into an online system. Based on the test, the hardware can work for 16 h when fully charged and requires 39.91 s to complete one reading process, while the software can run all screens without trouble.
Teaching–learning-based optimization (TLBO) is a meta-heuristic algorithm that simulates the process of teacher and student (or learner) interaction in transmitting knowledge. The algorithm is relatively simple to implement, with free-tuning parameters for balancing exploration and exploitation of the solution space. TLBO contains two phases, namely, teaching and learning. In this paper, self-adaptive Gaussian bare-bones TLBO (SABBTLBO) is proposed for improving TLBO and Gaussian bare-bones TLBO (BBTLBO) performance. In the SABBTLBO, Gaussian bare-bones and the original teaching phase in TLBO become more adaptive by a mechanism based on the learner’s rank. For the new learning phase, an adaptive scaling factor based on the rank mechanism is used to modify the neighborhood search strategy. A restarted mutation approach is also added in the learning phase. The developed SABBTLBO is compared with six state-of-the-art TLBO variant algorithms for inversion of synthetic multiple self-potential (SP) anomaly sources. The proposed SABBTLBO algorithm is also tested and compared with several algorithms applied for field SP data from different locations in the world including India, Portugal, and Indonesia, using the assumption that SP data are sourced by idealized bodies (simple geometric model or thin sheet model). The inversion of multiple SP anomaly sources using SABBTLBO is used not only for determining the best model parameters, but also their uncertainties. The latter is estimated from the equivalence region of the set of possible solutions via cost function topography evaluation. Significant results were obtained and can be associated with the geology of studied area.
In this work, we developed a QSAR model using the K-Nearest Neighbor (KNN) algorithm to predict the corrosion inhibition performance of the inhibitor compound. To overcome the small dataset problems, virtual samples are generated and added to the training set using a Virtual Sample Generation (VSG) method. The generalizability of the proposed KNN + VSG model is verified by using six small datasets from references and comparing their prediction performances. The research shows that for the six datasets, the proposed model is able to make predictions with the best accuracy. Adding virtual samples to the training data helps the algorithm recognize feature-target relationship patterns, and therefore increases the number of chemical quantum parameters correlated with corrosion inhibition efficiency. This proposed method strengthens the prospect of ML for developing material designs, especially in the case of small datasets.
Article accessible for free here: We appreciate the accompanying technical Comment by Murphy et al.1—a group of practicing orthopaedic surgeons—on our original paper2. However, we strongly disagree with their conclusion that a reductionist approach was taken in the diagnosis of surgical amputation in a 31,000-year-old individual (TB1) from Borneo. We note that a complete systematic differential diagnosis was indeed completed (Extended Data Table 1); this process involved careful consideration of the most common and banal conditions first, such as accidental fracture, before considering the possibility of more rare and unusual circumstances. Through this iterative process, fracture was first eliminated as a possibility, followed by natural causes of amputation. Surgical amputation was the remaining scenario left that completely described the characteristics that we observed in the bone. As is standard for palaeopathological analysis, a detailed description of the pathology was undertaken, including recording of the location and aspect of affected bone, the type of bone affected, the mechanism of injury, the degree of healing, complications to healing, force and fracture type. This detailed analysis means that certain aspects of trauma were excluded from the differential diagnosis due to the specific location of the injury. It was at this stage that physeal fractures, which Murphy et al.1 correctly recognize as common fractures in early adolescence, were disregarded from the differential diagnosis as the affected portion of the bone was at the site of the mid to distal lower third diaphysis and not near to the distal metaphyseal region (Fig. 1). We surmise that Murphy et al.1 may have mistaken the thin cortices of TB1’s tibia and fibula for that at the diaphyseal-to-metaphyseal transition in the bone that is naturally thin. However, with TB1, the cortices in these bones (and indeed also the left femur) are thin due to extreme atrophy that probably occurred over a number of years. We acknowledge that two-dimensional photographs and radiographs can misrepresent to readers injuries that, in reality, occur in three dimensions. Thus, we provide publicly available three-dimensional computed tomography files of the amputation.
Access to inclusive sanitation for people with disabilities (PWDs) remains a global challenge, including in Indonesia, where 10–15% of its population is disabled. Inclusive sanitation facilities can be achieved when PWDs are involved in the sanitation-related decision-making process, e.g., designing toilet that meets their needs. This study aims to investigate the situation of the sanitation facility in houses of PWDs and understand knowledge, attitude, and practices related to PWD participation in sanitation programs using a case study in two provinces in Indonesia: Nusa Tenggara Barat and Nusa Tenggara Timur. Quantitative data were taken from 129 PWD households, and qualitative data were from in-depth interviews with relevant stakeholders. The latter was presented in a causal loop diagram. Less than 5% had inclusive sanitation at home, mainly due to no supportive tools and bins. The knowledge levels related to sanitation and PWDs participation in sanitation programs were relatively low. Economic condition was one of the barriers for PWDs to participate in the sanitation program. Statistical analysis found that a higher household head education level was associated with a more positive attitude and higher PWD participation in sanitation programs. Although Indonesian law supports PWD participation, the implementation remains a challenge. This study also underlines the need for capacity building in facilitating PWDs’ involvement in sanitation programs and community meetings. Finally, barriers to PWD participation can come from different levels and actors, e.g., the family, the community, the district level, and the PWD itself, indicating the need to involve actors at all levels to enhance PWD participation in the sanitation program that leads to inclusive sanitation facilities for all groups.
In this research, a microclimate conditioning chamber was built for capsicum frutecens research. Our growth chamber-named AgroCUBE-is an automated growth chamber which can be controlled remotely. AgroCUBE was designed to control temperature, air relative humidity, and soil humidity. It is also equipped with three internal camera, LED based lighting module, an LCD user interface for onsite user, and a single board computer serves as local server in which climate data and plant image from internal camera will be stored. We also made a communication architecture consist of a cloud server-to which AgroCUBE will send climatic data as well as plant image- and mobile apps so user can maintain and control AgroCUBE remotely. In a two hours test, it is shown that AgroCUBE was able to maintain chamber temperature at 27°C with stability of±1°C and air relative humidity at 70% RH with stability of±6% RH. Meanwhile, it also able to increase soil humidity from 55% to 85% in 6.5 minutes. This temperature and humidity range has been confirmed as optimum level for most vegetables in tropical region. Meanwhile, both the onsite (LCD) as well as offsite (mobile apps) user interface was designed with maximum of ten operational steps and maximum delay of ten seconds. It has been confirmed to work perfectly.
Bird Strike Impact is a phenomenon that occurs when one or a flock of birds crashes into an airplane, causing damage to the aircraft structure, especially during the take-off and landing phases. One of the aircraft components that experience the most cases of bird impact and catastrophic consequences is the wing. This paper deals with a numerical simulation using the explicit-dynamic Finite Element Method (FEM) on bird impact testing on wing leading edge of the 80 passenger aircraft referring to CASR (Civil Aviation Safety Regulation) Part 25. The bird modeled as an impactor used is simplified into a cylinder with a uni material hemisphere with a mass of 1.82 kg (4 lbs). The leading edge specimen as the target used is a wing section attached to the rigging. The Smoothed Particle Hydrodynamic (SPH) formulation approach is used in modeling birds as fluids with soft body characteristics. The speed of the bird relative to the aircraft is 145 m/s. The thickness and the material of the skin component was varied to reduced the reaction force of the frontal leading edge. The 2 mm of skin thickness with combined Al 7075-T6 and Al 2024-T3 has the lowest reaction force, namely 50 kN. This research conclude that the structure thickness variable gave a significant difference in maximum deflection and the reaction force compared to the material used.
Inorganic scintillators play a major role in ionizing radiation detection due to their high versatility to detect multiple radiation sources such as X-rays, gamma-rays, alpha, beta, and neutron particles, and their fast and high light yield, making them especially convenient for imaging, spectroscopy, and timing applications. Scintillators-based detection systems are found, among various applications, in medical imaging, homeland security, high-energy physics, industrial control, oil drilling explorations, and energy management. This Review discusses advances and prospects of perovskite scintillators, particularly low-dimensional hybrid organic-inorganic perovskite crystals and all-inorganic perovskite nanocrystals. We highlight the promise of two-dimensional lithium-doped (PEA)2PbBr4 crystals and CsPbBr3 nanocrystals as scintillators with high light yields, exceeding 20 photons/keV, and fast decay times of less than 15 ns. Such a combination may result in fast-spectral X-ray imaging, an output count rate exceeding 30 Mcps/pixel in photon-counting computed tomography, and coincidence timing resolution of less than 100 ps in positron emission tomography. We review recent strategies to further improve light yield, decay time, and coincidence timing resolution through light-matter interactions such as extraction efficiency enhancement and Purcell-enhanced scintillators. These advancements in light yields and decay times of perovskite scintillators will be particularly useful in the medical and security applications.
This study examines the interplay of air connectivity, sports events, infra-structures, and fiscal support during the period 2017 and 2022 in a designated area called Special Economic Zone in Mandalika, Lombok Island, West Nusa Tenggara to boost tourism development in Indonesia by utilizing big data cognitive analytics. We examine the tourism development impacted by the MotoGP event in 2022 and air connectivity. Further, this paper discusses the network connectivity of flights at Zainuddin Abdul Madjid International Airport during the COVID-19 Pandemic and the new normal. We found that the combination of an international airport, globally recognized sports events, and government support has directly and positively improved the tourism industry's performance in the country and especially within Lombok Island. We suggest policy recommendations to support economic activities in Mandalika's Special Economic Zone and its hinterland to maintain business sustainability and utilize the existing infrastructures at the optimum level. Lessons learned from the Indonesian experience could help other developing countries that are devising policies and strategies to develop the tourism industry by employing proper instruments such as infrastructure, events, and fiscal policies.
Bacterial nanocellulose (BNC) can be produced using a variety of substrates as fermentation medium for use in various biomaterial applications. This study aimed to optimize the production of and characterize the BNC derived from lemongrass leaves (L-BNC) obtained by symbiotic culture of bacteria and yeast (SCOBY) kombucha. The lemongrass leaves (10, 15, and 20 g/L) and sugar (30, 50, and 70 g/L) were incubated for 14 d at 30 °C. The optimal treatment was used to ferment kombucha for 21 days at 30 °C, with initial SCOBY inoculum of 3% w/v and kombucha of 10% v/v for the resulting L-BNC. The L-BNC was characterized using scanning electron microscopy-energy dispersive X-ray (SEM-EDX) spectroscopy, Fourier-transform Infrared spectroscopy (FT-IR), and X-ray diffraction analysis (XRD). The optimal parameters of the lemongrass kombucha fermentation production process were lemongrass content 10 g/L and sugar content 30 g/L with the incubation period of two weeks for 56.8 g/L of SCOBY production. The SEM analysis of L-BNC revealed a three-dimensional fibrous extremely fine network of randomly arranged nanofibrils with diameter of 163 ± 34 nm and hydrogen bonds present in L-BNC fibril units. Meanwhile, XRD results showed a crystallinity of 67.2%.
In most tropical countries, carbohydrate-based agricultural products occur in large quantities. Wider utilization of local starch crops will offer various economic and ecological advantages. Local starch crops can be a catalyst for rural industrial development and eventually open up new markets. The potential glucose yield from the typical Indonesian starches (edible canna, arrowroot, sago, and sweet potato) using lower dosage of cold-starch hydrolyzing enzyme preparation Stargen™ 002 was compared with that of corn and potato. The glucose equivalent yield reached 88.4 g/L and 86.3 g/L after 24 h of hydrolysis when 40% (w/v) raw sago and sweet potato starches were used, respectively, as compared to corn starch (89.6 g/L). While arrowroot and edible canna gave much lower amounts (53.3 g/L and 39.7 g/L, respectively). This study demonstrates that sago and sweet potato starches may provide interesting alternatives to corn starch in a cold hydrolysis conversion process of starch into glucose.
Large-bodied Panulirus ornatus lobsters are economically important because they are an aquatic biota. It is one of the most important commodities in the city of Tarakan. The aim is to analyze the growth patterns and mortality of P. ornatus from the West Waters of Tarakan City. Method using a quantitative descriptive. The purposive sampling method was used by dragging the gill net fishing gear to the P. ornatus lobster ground area, and the collection was carried out 16 times in 7 months (December 2021-July 2022). The results of P. ornatus showed that the male sex ratio was higher than the female. The growth model was allometrically negative, and the criteria for the condition index were fat and thin. The growth pattern of Model Von Bertalanffy males is slower than females. However, the growth rate to achieve asymptotic growth for males is faster than for females. The total mortality, catch mortality, and exploitation rate of males was higher than females. However, the mortality of the female nature was higher than that of males. P. ornatus should be managed in the waters of West Tarakan using the domestication and restocking technique to increase sustainability.
The alteration of ACE2 expression level, which has been studied in many diseases, makes the topic of ACE2 inducer potential crucial to be explored. The ACE2 inducer could further be designed to control the ACE2 expression level, which is appropriate to a specific case. An in vitro study of well-characterized carbon dots (CDs), made from citric acid and urea, was performed to determine their ability to modulate the ACE2 receptor. Gene expression of ACE2 was quantified using concentrations adjusted for IC50 results from CDs viability assays in HEK 293 and A549 cell lines. RT-qPCR was used to assess the expression of the ACE2 gene and its induction effect in normal cell lines (HEK-293A). According to the results of the tests, ACE2 is expressed in HEK-293A cell lines, and diminazene aceturate can increase ACE2 expression. The effect of CDs on ACE2 gene expression was further examined on the cell lines that had previously been induced with diminazene aceturate, which resulted in upregulation of the ACE2 expression level. An in silico study has been done by using a molecular docking approach. The molecular docking results show that CDs can make strong interactions with ACE2 amino acid residues through hydrophobic interaction, π-π interaction, π-cation interaction, and ionic interaction.
Previous studies revealed that not all physical activities contribute to positive health results. Due to time limitations and energy deficits, involvement in physical activity might limit participation in another physical activity. Moreover, physical activities with different intensities, either vigorous, moderate or light, might have different patterns in deactivating or activating subsequent physical activities. This study examines the reciprocal effects of physical activities with different intensities and their effects on various health indicators. The reciprocal effect and its effect on health were overlooked in previous studies as the main research gap. The emerging digital activities raise how ride-sourcing and online activities encourage or discourage physical activities, in turn, health. This is the additional research gap. The 2019 Malang Greater Area dataset and Structural Equation Modeling are used in the analysis. The result of the study confirms that the reciprocal effects of physical activities are relevant to unravel the deactivation of other physical activities due to the commitments to take a specific physical activity. However, vigorous physical activities at home are still performed when people have commitments to do moderate physical activities at work and home, vigorous sports and cycling. The results also confirm that ride-sourcing significantly provides greater opportunities to perform physical activities than online activities. Ride-sourcing is also found to reduce the negative health effects of vigorous physical activities at work. Not all physical activities, however, correlate with positive health performances. Active travel can be suggested to maintain older people’s health, whereas vigorous sports are good for young adults.
Humanoid robot is able to mimic repetitive activities done by human. By having them, humans can focus on tasks that require extra focus, while leaving the simple one to be done by humanoid robot. To extend the functionality of the 3D-printed upper-body humanoid robot, a camera along with a machine learning algorithm is implemented. In this case, their responses can be categorized based on the gesture it sees. In this paper, the authors evaluate the performance of an upper-body humanoid robot that implements CVZone. The method of evaluation is conducted under three different distances, and each distance has three different brightness levels. It is found that the success rate is highest at the shortest distance which is 50 cm, and under medium-lighted environment. As the distance increases, the hand gesture gets harder to differentiate. At the same time, low or high brightness environment makes the image that contain hand gesture hard to interpret, thus lowering the success rate. Finally, hand gesture that involves third and little finger has the lowest success rate of 75%, while the movement that involves three fingers simultaneously has the second lowest success rate of 80.9%. Meanwhile, simple hand gesture such as clenched-fist or lifting a thumb has 100% success rate under all condition.
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24,087 members
Elvi Restiawaty
  • Department of Bioenegy Engineering and Chemurgy
Henndy Ginting
  • School of Business and Management
Ketut Wikantika
  • Remote Sensing and Geographical Information Sciences, Faculty of Earth Science and Technology
Irsyad Nashirul Haq
  • Engineering Physics
Ganesha 10, 40132, Bandung, West Java, Indonesia
Head of institution
Prof. Ir. N. R. Reini Djuhraeni Wirahadikusuma, MSCE, PhD
+62 22 250 0935
+62 22 250 0935