Pavel O. Savelev, Andrei I. Shumeiko, Victor D. Telekh
The development of dynamic missions of small satellites requires the development of efficient, compact, and reliable propulsion systems (PSs). This paper investigates a propellant storage and supply system (PSSS), utilizing alternative solid-state propellants in the form of wire. To establish the background to the suggested solutions implemented in the proposed system, two types of comparative analysis were performed. The first one compared different types of propellant management system designs while the second juxtaposes a variety of propellants. It is shown that the solid-state systems for small satellite operations are advantageous, while the selection of propellants should be focused on safe operations and operational requirements. The principle of operation and structural design of the proposed wire-based solid-state propellant management system are discussed, including the assessment of its engineering realization. The strategies to mitigate the potential problems with the system’s operations such as propellant unwanted deposition and corrosive effects are suggested. An example of using the proposed system is provided, which considers a deep space dynamic mission case. The proposed PSSS architecture is dedicated to increasing the energy efficiency, resilience to environmental factors, and suitability for small satellite platforms, including that of the CubeSat format.
Engineering machinery, tools, and implements, Technological innovations. Automation
This paper presents an analysis of the time-dependent response of a spherical container to internal pressure that increases over time. The wall of the container is relatively thin, in the sense that the wall thickness is negligible in comparison to the container’s radius. The wall is composed of three layers. The two surface layers of the wall are identical, i.e., they are made from the same material and have the same thickness. One of the most important features regarding the response of the wall layers is the non-linear creep. The stresses and strains are determined, and their relationships with the parameters of the layers are studied.
I Made Sukarsa, Deden Witarsyah, I Putu Agung Bayupati
et al.
The development of chatbots to access database services and information systems has triggered a lot of research on frameworks for service development, including the development of ISONER (Information System On Internet Messenger). This framework consists of multiple phases including pattern recognition, query processing, and response generation. In its implementation, the framework develops pattern recognition services that are currently based on Natural Language Processing (NLP). Improved pattern recognition algorithms enhance the system’s ability to accurately interpret user intent. The pattern recognition used in this research utilizes built-in plugins from MySQL, namely N-gram and Full-Text Search, which can be run directly on the MySQL engine to reduce latency and do not require another programming language. The FTS and fourgram algorithms gave the best results when applied on 100 test data points, with a threshold of 0.91, accuracy of 91%, precision of 99%, and recall of 92%; the average computation time was 19 s for 100 test data points and 2 min 49 s for 1000 data points tested simultaneously.
Alexander S. Efimov, Stanislav A. Eroshenko, Pavel V. Matrenin
et al.
This study emphasizes the urgent need for systems that monitor the operational states of primary electrical equipment, particularly power transformers. The rapid digitalization of and increasing data volumes from substations, coupled with the inability to retrofit outdated equipment with modern sensors, underscore the necessity for algorithms that analyze the operational parameters of digital substations based on key power system metrics such as current and voltage. This research focuses on digital substations with Architecture III and aims to develop an algorithm for processing digital substation data through an appropriate mathematical tool for time-series analysis. For this purpose, the fast discrete wavelet transform was chosen as the most suitable method. Within the framework of the research, possible transformer faults were divided into two categories by the nature of their manifestation. A mathematical model for two internal transformer fault categories was built. The most effective parameters from the point of view of the possibility of identifying an internal fault were selected. The proposed algorithm shows its effectiveness in the compact representation of the signal and compression of the time series of the parameter to be monitored.
Engineering machinery, tools, and implements, Technological innovations. Automation
Yusuke MIURA, Akito TERAKADO, Hiroki SAKAKIMA
et al.
Impact vibration due to the train passage at the joint of tongue rail has been known to induce the fatigue fracture of the hinged lug of turnouts. The impact vibration is considered to be enhanced by the mismatch of rails, the gap between the tongue rail and the base plate, and the loss of the tightening force of the bolt at the joint plate. However, the detailed mechanism has been unrevealed since the direct observation of the joint during train passage is inaccessible. In this study, we first measure the displacements of the tongue rail at the joint during train passage using small-size cameras. We evaluate the turnout whose hinged lug was broken. Displacement measurements show that the heel of the tongue rail (close to the joint) moves vertically downward by 3.9 mm and the toe of the tongue rail moves vertically upward by 2.3 mm when the train passes through the joint. Finite element analysis reveals that the downward displacement of the heel is caused by the gap between the tongue rail and the base plate and the upward displacement of the toe is caused by the rotation of the tongue rail around the supporting base plate. Acceleration measurements show that two peaks of impact acceleration enlarge the acceleration amplitudes (4400–7500 m/s2). Finite element analysis reveals that the first and second peaks are caused by the collision between the tongue rail and the wheel and that between the tongue rail and the base plate, respectively. Our results indicate that the gap between the tongue rail and the base plate should be minimized in addition to the mismatch of rails to reduce the amplitude of the impact vibration.
Mechanical engineering and machinery, Engineering machinery, tools, and implements
Redundancy in ship systems is provided to ensure operational resilience through equipment backups which ensures system availability and offline repairs of machinery. The electric power generation system of ships provides the most utility of all systems, hence is provided with good level of standby units to ensure reliable operations. Nonetheless, the occurrence of undesired black outs are common onboard ships and portends a serious danger to ship security and safety. Therefore, understanding the contributing factors affecting system reliability through component criticality analysis is essential to ensure a more robust maintenance and support platform for efficient ship operations. In this regard hybrid reliability and fault detection analysis were conducted to establish component criticality and related fault conditions. A case study was conducted on a ship power generation system consisting of 4 marine diesel power generation plants onboard an Offshore Patrol Vessel (OPV). Results from the reliability analysis indicate overall low system reliability of less than 70 per cent within the first 24 months of the 78 operational months. Component criticality using reliability importance measures was used to identify all components with more than 40 per cent contribution to sub systems failure. Additionally, machine learning was used to aid the reliability analysis through feature engineering and fault identification using Artificial Neural Networks classification. The ANN has identified failure patten threshold at about 200kva which can be attributed to overheating, hence establishing link between component failure and generator performance.
The objective of this study is to incorporate varied geospatial data into CAD/BIM systems, which are now essential design tools for architects. Those geospatial data include digital information of topography, water features, roads and streets, existing buildings, and so on. Those data have been released by the government as public information, and their full utilization in actual design projects would be highly beneficial.
The article discusses the aspects of obtaining red-colored phosphate coatings on the surface of steel at low temperatures. The solution for color phosphating is based on a modified composition based on the chemical «Majef» with sodium nitrite as an accelerator, organic additives of glycerin and Trilon B to improve the quality of precipitated phosphate coatings, and the preparation of OS-20 for emulsifying and wetting the surface. To precipitate red phosphate coatings, it is proposed to introduce copper salt into the composition of the phosphating solution. In the phosphating solution with the addition of copper salt, contact deposition of copper occurs before the formation of a phosphate film on the surface of the steel. This copper layer stains the resulting phosphate coating but does not adhere to the steel surface. To obtain a red phosphate coating of satisfactory quality, it is recommended to first soak the steel product in a modified cold phosphating solution for 15 min, and after the formation of a thin layer of phosphate film on the surface of the steel, introduce copper salt into the solution. Red phosphate coatings are inferior in their protective abilities to unpainted phosphate films; they have greater roughness and high porosity. Although red phosphate coatings have a protective ability, their anticorrosive properties should be improved by additional varnish treatment.
Collaborative learning has been widely acknowledged as a successful teaching method within the education field, with research indicating its positive impact on student outcomes. During the COVID-19 pandemic, when all courses transitioned online due to lockdown measures, many universities employed learning management systems to facilitate continued group work among students. However, forming effective student groups remained challenging, particularly given the large number of enrolled students. To address this issue, this study proposes the application of an artificial intelligence (machine learning) solution to automatically group students based on their behaviours and interactions within an e-learning environment. This paper explores the potential of machine learning (ML) algorithms in assisting educators to create heterogeneous groups, considering various student attributes, such as behaviour and performance, to optimise collaborative learning outcomes. Students’ performance within a module was compared using a wiki activity that employed group work over the course of two academic years. In the first experiment, groups were formed randomly, while in the second experiment, students with similar behaviours were firstly identified using a clustering algorithm and then organised by an additional algorithm into heterogeneous groups. The results demonstrate the efficacy of the machine learning solution compared to the random approach in assisting educators with group formation for a collaborative activity such as the wiki, confirmed by a comparative analysis showing an improvement in student performance and satisfaction. This research contributes to the advancement of online education through the creation of more effective group dynamics using machine learning algorithms, thereby improving overall student learning.
Ihsan Ur Rahman, Hamin Jaafar Mohammed, Misbah Ullah
et al.
Global warming is a serious concern worldwide, while there are many contributors to rise the temperature of earth. One major source to it, is air pollution. It is of utmost importance to apply the necessary remedial actions to address the contaminants in outdoor and indoor environment. In this research a step is taken to treat flue gases, for which membrane technology is introduced. A porous ceramic membrane is synthesized from calcined porous alumina (Al2O3) and activated washed fly ash. Some other additives like starch (C6H10O5) n, binder solution along with ethyl silicate (C8H2O4Si) and a deflocculating agent carbonic acid (H2CO3), are employed. Alongside it, some of the issues are discussed which are faced during fabrication of porous ceramic membrane i.e., crakes in membrane sample, non-active reactants issue, un-even rise or fall during de-moisturization or sintering steps. Further, the membrane sample is characterized through different test including: Further, the membrane sample is characterized through different test including thermogravimetric analysis (TGA) and DTG, which shown a satisfactory results, as there is negligible percentage weight loss after 750°C. X-ray fluorescence (XRF) for fly ash portrayal and X-ray diffraction (XRD) analysis for structure assessing are conducted, which described that the fabricated membrane has a crystalline structure as like ceramic. Archimedes Principal technique is used to determine bulk density, and porosity of the membrane sample, the values are 4.484 g/cm3, and 62.5% respectively. Average pore size of 7.6 µm is find out through optical microscopy test, similarly mechanical strength is found to be 2.7 MPa. Furthermore, a pilot scale visual permeability test is performed for flue gases treatment of combusting fuel containing tyre and coal powder. The results show the compatibility of the fabricated porous ceramic membrane to be utilized for treatment of flue gases.
Engineering machinery, tools, and implements, Mechanics of engineering. Applied mechanics
Thiago Glissoi Lopes, Paulo Roberto Aguiar, Thiago Valle França
et al.
Additive manufacturing (AM) has been playing a crucial role in the fourth industrial revolution. Sensor-based monitoring technologies are essential for detecting defects and providing feedback for process control. Acoustic emission (AE) sensors have been used for a long time in a wide range of processes and fields, but they are still a challenge in AM processes. This work presents a study on the AE signals in the time-domain—raw and root mean square (RMS) values—regarding their behavior during the manufacture of a single-layer part in the fused filament fabrication process for two infill patterns. The tests were conducted on a cartesian 3D printer using polylactic acid material. The AE sensor was attached to the printer table through a magnetic coupling, and the signal was collected by an oscilloscope at 1 MHz sampling frequency. It was found that the raw AE signals behaved quite differently not just for the two infill patterns, but within the same pattern. The raw and RMS AE signals contained many spikes along the whole process, but the higher ones were those generally occurring at the end and/or start of a fabrication line. The RMS values, however, were useful for finding the start and end times of each fabricated line for both patterns. The mean RMS values showed nearly constant but distinct averages for the extruder-only, table-only and extruder–table movements.
Control moment gyros are known for their applications in attitude stabilization. These actuators are susceptible to malfunction, which results in faults and failures. Therefore, diagnosing the faults can improve the reliability of completing a mission while reducing maintenance costs. Thus, a model-based fault diagnosis method is proposed here. The intended algorithm is an enhanced version of previous work by the author. The enhancement employs a condensed approach to alleviate the delay caused by the filter’s confidence in its estimations. A case-study on a closed-loop controlled satellite is provided along with an extensive Monte Carlo simulation to evaluate the proposed method’s performance. The results show that the enhanced method can achieve superior performance while requiring less computational resources by eliminating extra grid search loops.
Engineering machinery, tools, and implements, Systems engineering
Fitri Khoerunnisa, Yustika Desti Yolanda, Mita Nurhayati
et al.
A detailed study on the synthesis of chitosan nanoparticles under ultrasonication is reported in this paper. By using this simple technique, chitosan particles in nanometer range can be easily prepared without using any harmful and expensive chemicals. The results show that increasing the ultrasonic irradiation time and ultrasonic wave amplitude are the key factors for producing discrete chitosan nanoparticles with narrow particle size distribution. The resulting nanoparticles show superior turbidity removal efficiency (75.4%) and dealkalization (58.3%) in wastewater treatment than the bulk chitosan solid (35.4% and 11.1%, respectively), thus offering an eco-friendly and promising approach for treating wastewater via the coagulation/flocculation process.
Engineering machinery, tools, and implements, Technological innovations. Automation
This research aims at developing a technology strategy coordinating with international regulations taking their recent globalization into account. Since recognizing the trend of establishment of the international regulation is indispensable as the assumption for building the strategy, this paper categorizes established and amended international regulations focusing on the safety requirements in the International Maritime Organization (IMO). The research firstly reviews the scheme and procedure for developing the new requirements. Then, based on IMO-MSC documents on new work program proposed by member States for 14 years, three categories, a motive for the development of safety requirements, required safety area, and regulatory issues, are investigated as significant factors. The result shows the identification of taxonomic classification in each category. This paper also shows the points to be considered, diversity of a motive and potential background that cannot be found in the IMO documents such as domestic political situation. Since the categorization in this paper can be generalized easily, application to other areas, such as international aviation and automobile sectors, are recommended.
Mechanical engineering and machinery, Engineering machinery, tools, and implements
Noor Abdulkareem AL-Ali, Makarim H. Abdulkareem, Iman Adnan Anoon
In this study, two systems of bio-ceramic coating (45S5 bioactive glass and hydroxyapatite) were used in order to compare between them for biomedical applications. Each system consists from two layers of coating done by electrophoretic deposition (EPD) technique on 316L stainless steel material as substrate. Two types of biopolymer were used (Chitosan with Gelatin) as first layer of coating. Taguchi approach with L9 array was used in order to choose the best conditions (concentrations, voltage and time) for coating layers. Each system consists of two layer (biopolymer (first layer) and bioceramic (second layer)) materials. The optimum parameters for first layer of biopolymer was (3g/L concentration, 20 voltage and 3 minute) while optimum parameters for second layer of bioceramic group (6g/L concentration, 30 voltage and 1 minute) for 45S5 BG system and (6g/L concentration, 40 voltage and 1 minute) for HA system. Zeta potential test were employed to measure suspensions stability. The tape test method was used to evaluate the adhesion between substrate and coating layers, the results show that the percentage of removal area for optimum coating layer (biopolymer, 45S5 BG and HA 8.06%, 10.668%, 6.01% subsequently). XRD inspection was used for identify the phases of coating layers. The Cyclic polarization test was used for evaluation of pitting corrosion resistance, the results show all layers gives good corrosion resistance but 45S5BG system gives the best corrosion resistance when compared with HA system.
Engineering machinery, tools, and implements, Mechanics of engineering. Applied mechanics
In haptic virtual reality (VR), there are two important challenges: one is the difficulty of reproducing a surface feeling with haptic devices, and the other is the presentation method used for the display. We developed a tactile mouse using palm presentation for the former challenge to tackle the issue, “which tactile perception is superior for texture recognition, active or passive touch?” In a psychophysical experiment, two oblique edges of dot-patterns are presented consecutively as simple textures, and human subjects compare them to determine which is larger. We evaluated the precision of perception using the difference threshold of the edge angles calculated by the constant stimuli method. Experimental results show that the perception precision at low edge movement speeds (45 and 90 mm/s) was higher than that at high speeds (130 and 170 mm/s), and moreover, that there was no significant difference in precision of the edge angle perception between active and passive touches. The former finding seems to be caused by how well the mechanoreceptive unit handles uneven surfaces. The latter finding is due to the mechanism of the efference copy of a motor signal provided from the motor cortex not having a significant influence on texture recognition. The tactile image deterioration induced by the object movement might be compensated for with information processing in the central nervous system, which keeps stable tactile image without help from the efference copy. This work contributes to developing the haptic device which provides visually impaired persons with the tactile map.
Engineering machinery, tools, and implements, Mechanical engineering and machinery
Aidel Kadum Jassim Al-shamary, Akar Dogan, Okan Ozdemir
et al.
In this study, the effect of low velocity impact response of Kevlar/carbon hybrid composite has been investigated. Then the impacted specimens were subjected to compression and buckling tests at room temperature experimentally. The height, width and thickness of the specimens are 150, 100 and 2.1 mm, respectively. Impact tests have been performed under different impact energy levels by using low velocity impact testing machine. Compression and buckling tests were conducted by Shimadzu testing machine. According to obtained results, the damage increases by increasing the impact energy level in the subjected specimens to impact test. Compression strength value is higher about 3 times than buckling strength value.
Engineering machinery, tools, and implements, Mechanics of engineering. Applied mechanics