A New Method of Manufacturing Hollow Shafts via Flexible Skew Rolling

The existing rolling process of large and long axle parts, such as the cross wedge rolling (CWR) process, requires special molds and larger equipment. Flexible skew rolling (FSR) hollow shafts with mandrel is a near net-shape rolling technology which can achieve the diversified production of rolled parts without special molds. It has significant advantages such as small equipment tonnage, small die size, low rolling load, simple process adjustment, and especially suitable for multi-variety and small-batch production. This paper proposes hollow train shafts formed by FSR with mandrel. Reasonable parameters were selected for experiments, and the forming process was calculated by finite element (FE) software. The experimental results are consistent with the simulation results, indicating that the FE model is reliable. The rolling force and rolling torque are analyzed by simulation. Finally, the microstructure of different positions of the rolled-piece is analyzed, and the microstructure of the rolled part is refined. It is provide a feasible scheme for the rolling of large hollow shaft parts.

Determining patterns in reducing the level of bio-destruction of thermally modified timber after applying protective coatings

This paper reports the analysis of the biological destruction of timber and the use of protective materials, which established that the scarcity of data to explain and describe the process of bioprotection, neglect of environmentally friendly agents lead to the biodegradation of timber structures under the action of microorganisms. Devising reliable methods for studying the conditions of timber protection leads to designing new types of protective materials and application technologies. Therefore, it becomes necessary to determine the conditions for the formation of a barrier for bacteria permeability and to establish a mechanism for inhibiting material biodegradation. Given this, the dependence has been derived to determine the proportion of destroyed material under the effect of microorganisms when using an antiseptic-hydrophobicizer, which makes it possible to evaluate biopenetration. Based on the experimental data and theoretical dependences, the share of destroyed timber was determined under the effect of microorganisms, which is equal to 1 for natural timber. At the same time, this value for thermally modified timber is 0.033, and, when it is protected with oil ‒ 0.009, respectively, exposed to the action of microorganisms for 60 days. It should be noted that the presence of oil, wax, and azure leads to blocking the timber surface from penetration. Such a mechanism underlying the effect of protective coating is likely the factor in the process adjustment, due to which the integrity of the object is preserved. Thus, a polymer shell was created on the surface of the sample, significantly reducing the penetration of microorganisms inside the timber, while the loss of timber mass during biodestruction did not exceed 2.5 %. Therefore, there are grounds to assert the possibility of targeted control over the processes of timber bio-penetration by using coatings capable of forming a protective film on the surface of the material

The Effectiveness of Video-Based Learning Media to Increase Student Economic Learning Outcomes During the Covid-19 Pandemic

The COVID-19 pandemic provides valuable lessons for the world of education, especially Indonesia's readiness for the learning process. Adjustment of the learning process that was previously in the form of face-to-face to internet-based learning. This study aims to determine the effectiveness of using video-based learning media in improving high school students' learning outcomes of Economics. The research method used is a descriptive research method with a survey approach. We collect data in this study, namely observation, interviews, and documentation, which were then analyzed by calculating the percentage of sample answers and tested using various theories. The sample in this study was determined according to the research needs of 119 respondents. This study shows the average respondent's answer is 4, 04 or categorized agree. Thus, based on the analysis conducted, video-based learning media improved student economic learning outcomes in high school during the COVID-19 pandemic. Video-based learning media is a practical learning resource during the covid-19 pandemic that makes it easy for students to understand economic learning materials. during the Covid-19 Pandemic. This research also contributes to similar research in the context of developing online learning media during the pandemic and digital era.

Engineering project control of comprehensive unit price fluctuation-time limit fluctuation-process adjustment

When an engineering project requires a lot of time and the construction environment is complex, the unit price of materials and personnel will change, the project construction will be hindered, and the construction plan of the project should be adjusted. These uncertain interference factors will cause the earned value analysis results are quite different from or even contrary to the actual situation, so there will not be enough impartial data to help managers to control project. To this end, this paper analyzes how the price fluctuations, process adjustment and the abnormal construction period will affect the construction schedule and cost effect respectively, and further studies the corresponding methods of earned value correction. Based on case analysis, this paper studies the comprehensive correction method of earned value when cost unit price changes, working procedure is adjusted and construction period fluctuates in an abnormal manner. The method improves the theory of earned value and provides reference for engineering practices on project management.

Application of Two Indigenous Strains of Microalgal Chlorella sorokiniana in Cassava Biogas Effluent Focusing on Growth Rate, Removal Kinetics, and Harvestability

Microalgae cultivation in wastewater is an emerging approach to remove its contaminants and generate microalgal biomass. This study aimed to screen and isolate potential strains in a cassava biogas effluent wastewater (CBEW) treatment system and produce algal biomass. Chlorella sorokiniana strains P21 and WB1DG were isolated from CBEW and found to grow by utilizing various carbon sources. Experiments conducted in a batch reactor using an unsterilized substrate were done to evaluate the nutrient removal and growth of isolated strains from CBEW. The results showed that C. sorokiniana P21 and WB1DG could achieve biomass accumulation of more than 2564 and 1301 mg L−1, respectively. The removal efficiencies of chemical oxygen demand (COD), total phosphorous (TP), and total inorganic nitrogen (TIN) were found up to be 63.42, 91.68, and 70.66%, respectively, in a WB1DG culture and 73.78, 92.11, and 67.33%, respectively, in a P21 culture. Harvestability of the P21 strain was examined using several coagulant–flocculants. FeCl3 was found to remove more than 90% of the cells. Nutrient removal and growth rates resulting from these indigenous strains with application of untreated CBEW support the possibility of this strain being a promising candidate to couple a CBEW treatment and algal biomass generation with minimal process adjustment.

Predictive Process Adjustment by Detecting System Status of Vacuum Gripper in Real Time during Pick-Up Operations

In manufacturing systems, pick-up operations by vacuum grippers may fail owing to manufacturing errors in an object’s surface that are within the allowable tolerance limits. In such situations, manual interference is required to resume system operation, which results in considerable loss of time as well as economic losses. Although vacuum grippers have many advantages and are widely used in the industry, it is highly difficult to directly monitor the current machine status and provide appropriate recovery feedback for stable operation. Therefore, this paper proposes a method to detect the success or failure of a suction operation in advance by analyzing the amount of outlet air pressure in the Venturi line. This was achieved by installing an air pressure sensor on the Venturi line to predict whether the current suction action will be successful. Through empirical experiments, it was found that downward movements in the z-axis of the vacuum gripper can easily rectify a faulty gripper suction operation. Real-time monitoring results verified that predictive process adjustment of the pick-up operation can be performed by modifying the z-position of the vacuum gripper.

Local Wisdom of Dayok Binatur in the Simalungun Community

This research is concerned with the local wisdom of Dayok Binatur in the Simalungun community. Local wisdom is a collection of knowledge, practices and beliefs that evolved through adaptive process (adjustment) passed from generation to generation through culture, associated with the relationship between living beings (including humans) and the surrounding environment (Berkes, 1993). In the Simalungun community, Dayok Binatur is made from chicken and arranged on a plate. It is used as a symbol of intermediary to convey a message, advice and hope delivered from one side of the family to the other and usually presented at the Simalungun community’s traditional and special events. This research was conducted using qualitative descriptive methods. The results show that there are ten parts of chicken meat called gori, namely the head (ulu), neck (borgok), breast (tuppak), left and right wing (habong), base of thigh (tulan bolon), thigh (tulan parnamur), leg (kais-kais), the egg-producing organ (tuahni), liver (bilalang), and tail (ihur). Four objects are used, such as the head (ulu), neck (borgok), wing (hahong), and leg (kais-kais), which carry cultural symbols and local wisdom. The head (ulu) refers to leadership; the neck (borgok) refers to problem solving; the wings (habong) refers to protection; and the leg (kais-kais) refers to responsibility. The local wisdoms in Dayok Binatur are needed to maintain the balance of life. Keywords: Local Wisdom, Simalungun, Dayok Binatur

Virtual Sound Field of the Roman Theatre of Malaca

In Hispania (present-day Spain and Portugal), there are 25 structures documented of classical Roman open-air theatres, of which 10 are in the south, in the Roman Baetica (Andalusia). The Baetica embraced the progress of urbanisation in the time of the Roman emperor Augustus, where theatres, built in stone, were the foci of entertainment, performance, and propaganda of the empire. The Roman theatre in Malaga presents the archaeological remains of the main vestige of the Roman Malaca. It is located in the historical centre of the city, at the foot of the hill of the Muslim Alcazaba and was discovered in 1952. It is a medium-sized theatre whose design corresponds to a mixed construction that combines making use of the hillside for the terraces, in the manner of Greek theatres, with a major construction where rock is non-existent, thereby creating the necessary space for the stands. In this paper, the production process, adjustment, and validation of the 3D model of the theatre are analysed for the creation of a numerical predictive model of its sound field. Acoustic properties of the venue are examined and the effect of the Muslim Alcazaba and the hillside on the various acoustic descriptors is analysed. The results highlight the influence of this large stone surface mainly on the time decay parameters.

System integration for predictive process adjustment and cloud computing-based real-time condition monitoring of vibration sensor signals in automated storage and retrieval systems

As automation and digitalization are being increasingly implemented in industrial applications, manufacturing systems comprising several functions are becoming more complex. Consequently, fault analysis (e.g., fault detection, diagnosis, and prediction) has attracted increased research attention. Investigations involving fault analysis are usually performed using real-time, online, or automated techniques for fault detection or alarming. Conversely, recovery of faulty states to their healthy forms is usually performed manually under offline conditions. However, the development of intelligent systems requires that appropriate feedback be provided automatically, to facilitate faulty-state recovery without the need for manual operator intervention and/or decision-making. To this end, this paper proposes a system integration technique for predictive process adjustment that determines appropriate recovery actions and performs them automatically by analyzing relevant sensor signals pertaining to the current situation of a manufacturing unit via cloud computing and machine learning. The proposed system corresponds to an automated predictive process adjustment module of an automated storage and retrieval system (ASRS). The said integrated module collects and analyzes the temperature and vibration signals of a product transporter using an internet-of-things-based programmable logic controller and cloud computing to identify the current states of the ASRS system. Upon detection of faulty states, the control program identifies corresponding process control variables and controls them to recover the system to its previous no-fault state. The proposed system will facilitate automatic prognostics and health management in complex manufacturing systems by providing automatic fault diagnosis and predictive recovery feedback.