time calculation
Recently Published Documents


TOTAL DOCUMENTS

434
(FIVE YEARS 124)

H-INDEX

19
(FIVE YEARS 4)

Author(s):  
Yongjian Sun ◽  
Bo Xu

In this paper, in order to solve the calculation problem of creep damage of steam turbine rotor, a real-time calculation method based on finite element model is proposed. The temperature field and stress field of the turbine rotor are calculated using finite element analysis software. The temperature data and stress data of the crucial positions are extracted. The data of temperature, pressure, rotational speed, and stress relating to creep damage calculation are normalized. A real-time creep stress calculation model is established by multiple regression method. After that, the relation between stress and damage function is analyzed and fitted, and creep damage is calculated in real-time. A creep damage real-time calculation system is constructed for practical turbine engineering. Finally, a numerical simulation experiment is designed and carried out to verify the effectiveness of this novel approach. Contributions of present work are that a practical solution for real-time creep damage prediction of steam turbine is supplied. It relates the real-time creep damage prediction to process parameters of steam turbine, and it bridges the gap between the theoretical research works and practical engineering.


2021 ◽  
Vol 5 (1) ◽  
pp. 2
Author(s):  
Bassam Al-Naami ◽  
Feras Al-Naimat ◽  
Abdul-Majeed Raja M. Almalty ◽  
Paolo Visconti ◽  
Abdel-Razzak Al-Hinnawi

This paper proposes an electronic prototype of the Grooved Pegboard Test (GPT), which is normally used to test the presence of hand dexterity. The prototype imitates the geometrical dimensions of an on-the-market GPT device, but it is electronic, not manual like the one available now for users. The suggested electronic GPT device makes automated time calculation between placing the first and the last peg in their designated locations, instead of manually observing a stopwatch normally used during the GPT. The electronic GPT prototype consists of a fabricated wooden box, electronics (switches and microcontroller), and liquid crystal display (LCD). A set of 40 normal volunteers, 20 females and 20 males, tested the designed prototype. A set of six volunteers with chronic medical conditions also participated in evaluating the proposed model. The results on normal volunteers showed that the proposed electronic GPT device yielded time calculations that match the population mean value of similar calculations by the GPT device. The one-sample t-test showed no significant difference in calculations between the new electronic GPT and the manual GPT device. The p-value was much higher than 0.05, indicating the possible use of the suggested electronic GPT device.


2021 ◽  
Author(s):  
Vadim Goryachikh ◽  
Fahad Alghamdi ◽  
Abdulrahman Takrouni

Abstract Background information Natural gas liquid (NGL) production facilities, typically, utilize turbo-expander-brake compressor (TE) to generate cold for C2+ separation from the natural gas by isentropic expansion of feed stream and use energy absorbed by expansion to compress residue gas. Experience shows that during operational phase TE can exposed to operation outside of design window that may lead to machine integrity loss and consequent impact on production. At the same time, there is a lack of performance indicators that help operator to monitor operating window of the machine and proactively identify performance deterioration. For instance, TE brake compressor side is always equipped with anti-surge protection system, including surge deviation alarms and trip. However, there is often gap in monitoring deviation from stonewall region. At the same time, in some of the designs (2×50% machines) likelihood of running brake compressor in stonewall is high during one machine trip or train start-up, turndown operating modes. Also, typical compressor performance monitoring systems does not have enough dynamic parameters that may indicate machine process process performance deterioration proactively (real-time calculation of actual polytrophic efficiency, absorbed power etc.) and help operator to take action before catastrophic failure occurs. In addition, typical compressor monitoring systems are based on assumed composition and fixed compressibility factor and do not reflect actual compositions variations that may affect machine performance monitoring. To overcome issues highlighted above, Hawiyah NGL (HNGL) team has developed computerized monitoring and advisory system to monitor the performance of turbo-expander-brake compressor, proactively, identify potentially unsafe conditions or performance deterioration and advice operators on taking necessary actions to avoid unscheduled deferment of production. Computerized performance monitoring system has been implemented in HNGL DCS (Yokogawa) and utilized by control room operators on day-to-day basis. Real-time calculation, analysis and outputs produced by performance monitoring system allow operator to understand how current operating condition are far from danger zone. Proactive deviation alarms and guide messages produce by the system in case of deviation help operators to control machine from entering unsafe region. Actual polytrophic efficiency, adsorbed power calculations provide machine condition status and allow identifying long-term performance deterioration trends.


2021 ◽  
Vol 11 (2) ◽  
pp. 92-107
Author(s):  
Aldino Rizki Prayoga ◽  
Meizul Zuki ◽  
Yusril Dany

PT Mitra Kerinci is a company established in West Sumatra Province which is engaged in tea plantations and tea processing in its factories. PT Mitra Kerinci produces an average of 7,000 kg or 7 tons of green tea shoots per day. The production process for processing tea shoots, the factory sometimes does not reach the production target in accordance with the production target of the company. The goal of research  to determine the amount of the contribution of the motion study to the standard time and determine the amount of the contribution of the standard time to the increase in productivity in the final drying process at Ball Tea station, the production of tea shoots at PT. Kerinci Partners. This research an experimental research type and uses the same subject research design (treatment by subject design), namely the treatment is imposed on the same subject. The results of time calculations after the motion study on the process flow map reached 15,676.02 seconds. Then proceed with the calculation of the cycle time which reaches 825.41 seconds with the actual standard deviation obtained at 3.58 and the standard deviation of the subgroup distribution is 1.79. After knowing the results of the average cycle time, the actual standard deviation and the standard deviation of the subgroup distribution, the data uniformity test was continued, starting with calculating the BKA and BKB. The BKA calculation results obtained 830.78 and the BKB reached 820.04. So that in the data uniformity test the results reached 0.908. In the series of movements of the left and right hands after the repair, a cycle time of 825.41 seconds / unit of Ball Tea was obtained from the previous time, reaching 906.66 units / Ball Tea and getting a time difference of 81.25 seconds. In the calculation of the standard time, the normal time calculation is carried out first, after it is known that the result of the adjustment calculation reaches 1.12 so that the normal time is obtained with a total of 924.45 seconds. Continue to calculate the standard time and the results reach 1423.65 seconds with an allowance of 54%. This contributed to an increase in productivity by 5.7%.


2021 ◽  
Vol 6 (2) ◽  
pp. 105-112
Author(s):  
Muhammad Irwansyah Barkhati Setiawan ◽  
Arief Rahman ◽  
Faradilla ◽  
Muhammad Atta Bary

The importance of quality human resources in oil palm plantations in the field of harvesting to achieve high productivity, the success of harvesters is also very much determined by the pressure of the workload that is owned by workers, the workload depends on the job description compiled by the company. also the possibility of a workload that is too high. This study aims to analyze the working time of harvest employees and determine the productive, unproductive and personal time of harvest employees and analyze the number of harvest employees needed at PT. XYZ. This research was conducted at PT. XYZ Tanjung Batu Village, Derawan Island District, Berau Regency, East Kalimantan. This research was conducted using work sampling data collection method, namely observing the working time of harvest employees with 10 minutes intervals for 7 working hours by noting productive time, unproductive time and personal time. The results from the observations of researchers through the characteristics of harvest workers that affect the characteristics of age and height characteristics, it is proven that the age of 20 - 29 years is faster to reach the target or basis compared to the age of 30 - 49 years. And the characteristics of height have an effect on reaching the target, it is proven that height 170 - 179 cm reaches the target or base faster than 150 - 159 cm. And the observations of researchers from 16 respondents harvest productive working time an average of 73.52%, 17.20% unproductive time and 9.28% personal time. Calculation of the need for harvest workers in 1 division (763.33 ha) results in 33,644 rounded up to 34 harvest workers, the results needed in 1 division (763.33 ha) through the calculation of the time of completion of tasks (WPT).


2021 ◽  
Vol 20 (6) ◽  
pp. 1-36
Author(s):  
Márton Búr ◽  
Kristóf Marussy ◽  
Brett H. Meyer ◽  
Dániel Varró

Runtime monitoring plays a key role in the assurance of modern intelligent cyber-physical systems, which are frequently data-intensive and safety-critical. While graph queries can serve as an expressive yet formally precise specification language to capture the safety properties of interest, there are no timeliness guarantees for such auto-generated runtime monitoring programs, which prevents their use in a real-time setting. While worst-case execution time (WCET) bounds derived by existing static WCET estimation techniques are safe, they may not be tight as they are unable to exploit domain-specific (semantic) information about the input models. This article presents a semantic-aware WCET analysis method for data-driven monitoring programs derived from graph queries. The method incorporates results obtained from low-level timing analysis into the objective function of a modern graph solver. This allows the systematic generation of input graph models up to a specified size (referred to as witness models ) for which the monitor is expected to take the most time to complete. Hence, the estimated execution time of the monitors on these graphs can be considered as safe and tight WCET. Additionally, we perform a set of experiments with query-based programs running on a real-time platform over a set of generated models to investigate the relationship between execution times and their estimates, and we compare WCET estimates produced by our approach with results from two well-known timing analyzers, aiT and OTAWA.


Author(s):  
Yuedong Wu ◽  
Dashuo Chen ◽  
Jian Liu ◽  
Chuanyang Liang ◽  
Lei Zhang ◽  
...  

2021 ◽  
Vol 2097 (1) ◽  
pp. 012026
Author(s):  
Si Huang ◽  
Jiawei Guo ◽  
Tiankun Yi ◽  
Songfeng Li ◽  
Taizhong Wu

Abstract The calculation methods for vacuum system pumping were usually based on some simple theoretical models, the corresponding results had significant deviations from actual situations. In this study, medium and low vacuum systems (including vacuum chambers, pipes and pumps) were taken as research objects. With a measured vacuum system, and relationship between pump’s suction flowrate and inlet pressure, a new calculation method for vacuum pumping time was proposed, in which laminar or turbulent model was selected according to the pipeline’s flow state. New and traditional laminar method were used to calculate the pumping process of the measured system, which found that in the middle and high pressure stage, the pipeline flow was in turbulent state and the resistance was non-negligible. If the influence of turbulence was ignored, the calculated pressure drop would be faster than actual situation. The calculation result was verified by actual measurement result, indicating that new method is practical for vacuum pumping time calculation.


2021 ◽  
Vol 6 (3) ◽  
pp. 285-290
Author(s):  
Yu. M. Berezovsky ◽  
I. A. Korolev ◽  
T. A. Sarantsev

Thermal conductivity factor and specific isobaric heat capacity of food products are currently the most important parameters in the development of mathematical models for food freezing and thawing and in improving production technology. There is significant variance among the existing experimental data for the thermal conductivity factor in meat. Most of the modern calculated relationships are based on the nutritional approach, which favorably differs by the ability to calculate the thermophysical characteristics of any food products. However, the calculation error at the subcryoscopic temperatures may be 15% to 20%. The development of superchilling as a way of storing meat requires high accuracy of freezing time calculation, including vacuumpacked boneless meat. In the presented article, the authors investigated hydrogen index, cryoscopic temperature, frozen moisture proportion and thermal conductivity factor for beef M. longissimus dorsi samples of NOR and DFD grades. It was found that DFD beef is characterized by 10% to 12% higher values of thermal conductivity factor in comparison with NOR grade. Using the method of regression analysis, the authors developed empirical relationships for calculating the thermal conductivity factor of meat depending on its temperature and pH level. Unlike cryoscopic temperature and frozen moisture proportion, pH is easy to measure and may be easily used on a conveyor belt for more accurate assessment of meat thermophysical properties. With an increase in pH from 5.3 to 7, an increase in cryoscopic temperature is observed from minus 0.94 °C to minus 0.72 °C. It has been shown that one of the factors for the higher cryoscopic temperature and higher pH level of DFD beef is higher water-holding capacity with less strongly bound moisture.


Crystals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1236
Author(s):  
Agata Małysiak ◽  
Szymon Orda ◽  
Michał Drzazga

Calcium sulfate is a very important product of precipitation reactions in various branches of industry. The most common applications include building materials, impression materials in dentistry, immobilizing casts and an inactive ingredient of tablet excipients. It is also used as a drying agent and color glaze. In this paper, influence of various conditions, i.e., substrates concentration (supersaturation), temperature and rotational speed on induction time was investigated. The range of investigated parameters was 0.15–0.35 M for concentration with step of 0.05 M, 298–323 K with step of 5 K for temperature, and 1.67–8.33 s−1 for rotational speed with change every 1.67 s−1. The experiments were performed using visual and turbidimetric methods. It was proven that increase in all three investigated parameters resulted in shorter induction time. The turbidimetric method was found to be more precise, but still insufficient for concentrations below 0.15 M. Moreover, as a result of data analysis, a simple method of induction time calculation was proposed when arbitrary measurements in various concentrations are known.


Sign in / Sign up

Export Citation Format

Share Document