scholarly journals STATE-ORIENTED MAINTENANCE STRATEGY FOR DETERIORATING SEGMENTAL LINING OF TUNNEL

2018 ◽  
Vol 24 (6) ◽  
pp. 469-480 ◽  
Author(s):  
Qing Ai ◽  
Yong Yuan
Keyword(s):  
High Performance ◽  
Principal Part ◽  
Tunnel Lining ◽  
The Other ◽  
Limited Resources ◽  
Maintenance Cost ◽  
Maintenance Strategy ◽  
Maintenance Costs ◽  
Degradation Rates ◽  
Service State

The lining of tunnel is the principal part in ensuring its usage for transportation or utilities. Maintenance during operation is the way to keep structure in the state of high performance. To consider the efficiency of maintenance within limited resources (maintenance cost), state-oriented maintenance (SOM) approach is proposed. The SOM approach takes service state of the tunnel lining as a levelled target which should be maintained by different degrees of repairing measures. The evolution of service state of tunnel lining is modelled as a non-stationary Gamma process in this investigation, as this process can characteristic the variations of degradation rates. Two cases of numerical analysis with SOM approach give their lifetime maintenance costs. Case one (MS-1) sets SOM strategy with two-levelled service state. The other case (MS-2) adopts SOM strategy with multi-levelled service state. The numerical results demonstrate that the later one would reduce maintenance cost during the whole service life of tunnel lining.

Investigation of roller compacted concrete: Literature review

2019 ◽  
Vol 10 (3) ◽  
pp. 63 ◽  
Author(s):  
Gokhan Calis ◽  
Sadık Alper Yıldızel
Keyword(s):  
Urban Areas ◽  
Construction Projects ◽  
High Performance ◽  
Method Development ◽  
The Other ◽  
Maintenance Cost ◽  
Significant Shift ◽  
Conventional Concrete ◽  
Roller Compacted Concrete ◽  
Heavy Loads

Roller compacted concrete is a type of zero slump product produced from the same materials with conventional concrete. There are various methods for the design of RCC namely; corps of engineers’ practice, high paste method, roller compacted dam method and maximum density method. Development of RCC has led a significant shift in the construction projects primarily in dams as the traditional practise of placing, compacting and consolidation is slow. By using RCC in earth and rock filled dams made the construction process quicker and consequently shortened the duration of construction. RCC used dam projects and be completed 1-2 years earlier than the other dams as mentioned in the article of Bagheri and Ghaemian (2004). Use of RCC has substantially increased in the last decades especially for pavement applications. It has a low construction cost and can be done quickly compared to asphalt. It is widely constructed in areas/ roads carrying heavy loads in low speed. On the other hand, in recent years' utilization of RCC in urban areas such as highways and streets has also increased. It has been proved that RCC has a competitive advantage over high performance asphalt pavements in terms of high compressive strength, durability, low maintenance cost, longer service life. Like conventional concrete, fibre addition is widely preferred in RCC as well. Fibre addition has contribution to mechanical properties of RCC and sustainability.

scholarly journals Biofoam of Spittlebug, Poophilus costalis (Walker): Preferential Sites, Temperature Regulation, Chemical Composition and Antimicrobial Activity

Insects ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 340
Author(s):  
Kitherian Sahayaraj ◽  
Balakrishnan Saranya ◽  
Samy Sayed ◽  
Loko Yêyinou Laura Estelle ◽  
Koilraj Madasamy
Keyword(s):  
Antimicrobial Activity ◽  
Chemical Composition ◽  
High Performance ◽  
Host Plants ◽  
Ground Level ◽  
College Campus ◽  
The Other ◽  
Mimosa Pudica ◽  
Ft Ir ◽  
Gas Chromatography Mass Spectroscopy

The foam produced by nymphs of Poophilus costalis on eleven different host plants belonging to eight families on St. Xavier’s College campus in India was studied over five months. The chemical composition and antimicrobial activity of these biofoams were investigated. The results revealed that P. costalis preferred Theporsia purpurea and Mimosa pudica for laying their eggs and producing foam, over the other tested plants. P. costalis produce their foam on either nodes or internodes on monocotyledons (30%) (p < 0.05), whereas on dicotyledons, they produce more foam on the stems (63.8%) than on the leaves (6.2%) (p < 0.01). The number of nymphs in each piece of foam from P. costalis varied from 1 to 3 (mean = 1.8 per plant). They produced their foam (5.7 to 45.2 cm) from the ground level on a plant. The length and breadth of a piece of foam ranged from 1.0 to 3.9 cm and 0.6 to 4.7 cm, respectively. The foam tended to be cooler than the environment. Qualitative profiling showed that the foam consists of carbohydrates, including maltose; trypsin; amino acids; protease. The foam was also analyzed using a spectrophotometer, Fourier transform infrared spectroscopy (FT-IR), gas chromatography–mass spectroscopy (GC-MS), and high-performance liquid chromatography (HPLC). The antimicrobial activity of the biofoam was the greatest against Staphylococcus aureus, the growth of which was reduced by 55.9 ± 3.9%, suggesting that the foam could be used as an antimicrobial product. However, no activities were observed against Fusarium oxysporum and Candida albicans.

Individual Differences in Attention and the Prediction of Flight Criteria

1971 ◽  
Vol 33 (3_suppl) ◽  
pp. 1335-1342 ◽  
Author(s):  
Daniel Gopher ◽  
Daniel Kahneman
Keyword(s):  
Individual Differences ◽  
Selective Attention ◽  
Dichotic Listening ◽  
High Performance ◽  
The Other ◽  
Listening Test ◽  
Transient Instability ◽  
High Performance Aircraft

A dichotic listening test was constructed which requires S to monitor a relevant message and to ignore a concurrent message presented to the other ear. The test has promising validity for predicting different criteria of proficiency in flying high-performance aircraft. An analysis of the most valid type of errors suggests that a change in an existing orientation is accompanied by a transient instability of selective attention. Most errors in continuous attention are omissions, which indicate a failure of the listening set. Intrusions, which indicate a failure of selectivity, are rare and their frequency is not correlated to flight criteria.

On the Chemistry of Tetrabenzyl Thiuram Disulfide and Tetramethyl Thiuram Disulfide with Bis (Triethoxysilylpropyl) Tetrasulfide in Silica Compounds

2003 ◽  
Vol 76 (4) ◽  
pp. 876-891 ◽  
Author(s):  
R. N. Datta ◽  
A. G. Talma ◽  
S. Datta ◽  
P. G. J. Nieuwenhuis ◽  
W. J. Nijenhuis ◽  
...  
Keyword(s):  
High Performance ◽  
Room Temperature ◽  
Succinic Anhydride ◽  
Dynamic Properties ◽  
The Other ◽  
Resonance Spectroscopy ◽  
Reaction Products ◽  
Negative Effect ◽  
Higher Temperature ◽  
Analytical Tools

Abstract The use of thiurams such as Tetramethyl thiuram disulfide (TMTD) or Tetrabenzyl thiuram disulfide (TBzTD) has been explored to achieve higher cure efficiency. The studies suggest that a clear difference exists between the effect of TMTD versus TBzTD. TMTD reacts with Bis (triethoxysilylpropyl) tetrasulfide (TESPT) and this reaction can take place even at room temperature. On the other hand, the reaction of TBzTD with TESPT is slow and takes place only at higher temperature. High Performance Liquid Chromatography (HPLC) with mass (MS) detection, Nuclear Magnetic Resonance Spectroscopy (NMR) and other analytical tools have been used to understand the differences between the reaction of TMTD and TESPT versus TBzTD and TESPT. The reaction products originating from these reactions are also identified. These studies indicate that unlike TMTD, TBzTD improves the cure efficiency allowing faster cure without significant effect on processing characteristics as well as dynamic properties. The loading of TESPT is reduced in a typical Green tire compound and the negative effect on viscosity is repaired by addition of anhydrides, such as succinic anhydride, maleic anhydride, etc.

scholarly journals An enquiry concerning the nature of heat, and the mode of its communication

1832 ◽  
Vol 1 ◽  
pp. 139-147
Keyword(s):  
Principal Part ◽  
Cylindrical Vessel ◽  
The Other ◽  
Metallic Surface ◽  
Previous Trial ◽  
Flat Surfaces ◽  
Different Temperatures ◽  
The One ◽  
Quantity Of Heat

The importance of the investigation here entered into,—inasmuch as it applies to most of the operations of nature as well as art,—appears so manifest, that we shall not recapitulate what the author advances on that subject. Before he proceeds to the detail of his experiments for the purpose of computing the emissions of heat from various bodies under a variety of circumstances, he finds it necessary to premise a minute description of the principal part of the apparatus he contrived for his purpose. This instrument consists of a hollow cylindrical vessel of brass, four inches long, and as many in diameter. It is closed at both ends; but has at one end a cylindrical neck about eight-tenths of an inch in diameter, by which it is occasionally filled with water of different temperatures, and through which also a thermometer, constructed for the purpose, is occasionally introduced, in order to ascertain the changes of temperature in the fluid. As it was in the first instance only meant to observe the quantity of heat that escapes through the sides of the vessel, two boxes were contrived, filled and covered with non-conducting substances, such as eiderdown, fur, &c., which were fitted to the two ends or flat surfaces of the cylinder. Six of these instruments, with proper stands, and auxiliary implements of obvious construction, were prepared for the sake of comparative experiments. A previous trial was made with two of the cylinders, the vertical polished sides of the one being naked, and those of the other covered with one thickness of fine white Irish linen, strained over the metallic surface. Here it was found, contrary to expectation, that in a certain space of time the covered cylinder had lost considerably more heat than the naked one.

Modeling and Parameter Identification for Condition Monitoring of Surface-Mount Permanent Magnet Machines Under Magnet Demagnetization

2020 ◽  
Author(s):  
Fanny Pinto Delgado ◽  
Ziyou Song ◽  
Heath F. Hofmann ◽  
Jing Sun
Keyword(s):  
Permanent Magnet ◽  
Condition Monitoring ◽  
High Performance ◽  
High Efficiency ◽  
Health Condition ◽  
Maintenance Cost ◽  
Parameter Estimator ◽  
Two Phase ◽  
Machine Model ◽  
Surface Mount

Abstract Permanent Magnet Synchronous Machines (PMSMs) have been preferred for high-performance applications due to their high torque density, high power density, high control accuracy, and high efficiency over a wide operating range. During operation, monitoring the PMSM’s health condition is crucial for detecting any anomalies so that performance degradation, maintenance/downtime costs, and safety hazards can be avoided. In particular, demagnetization of PMSMs can lead to not only degraded performance but also high maintenance cost as they are the most expensive components in a PMSM. In this paper, an equivalent two-phase model for surface-mount permanent magnet (SMPM) machines under permanent magnet demagnetization is formulated and a parameter estimator is proposed for condition monitoring purposes. The performance of the proposed estimator is investigated through analysis and simulation under different conditions, and compared with a parameter estimator based on the standard SMPM machine model. In terms of information that can be extracted for fault diagnosis and condition monitoring, the proposed estimator exhibits advantages over the standard-model-based estimator as it can differentiate between uniform demagnetization over all poles and asymmetric demagnetization between north and south poles.

Using Risk Based Maintenance Optimization RBMO to Save Costs

2021 ◽  
Author(s):  
Khaled Ahmed Farouk Mohamed
Keyword(s):  
Risk Mitigation ◽  
Critical Item ◽  
Cost Benefit ◽  
Maintenance Cost ◽  
Maintenance Strategy ◽  
Critical Systems ◽  
Risk Matrix ◽  
Monetary Value ◽  
Maintenance Program ◽  
Systems Maintenance

Abstract Maintenance is a crucial pillar in plant integrity and availability. Saving money in maintenance should be established without affecting the asset's integrity. Based on this, the core of work is to maximize the maintenance return on investment (ROI). Maintenance ROI is the ratio between invested money in maintenance to mitigated risks due to maintenance actions. The objective is to minimize maintenance cost while maximizing assets integrity and availability. RBMO starts with ‘Maintenance Criticality Assessment’ (MCA) at unit/system level to define high (20 % of systems that represent 80% of risks), medium (20% of systems that represent 15% of risks), and low critical systems (60% of systems that represent only 5% of risks). Based on system criticality, a dedicated risk assessment is implemented to evaluate risks at tag level to define the worst maintenance action/s. High critical systems’ maintenance programs are developed using ‘Reliability-Centered Maintenance’ (RCM). Medium critical system maintenance program is developed using ‘Failure Mode, Effects and criticality analysis’ (FMECA). "Maintenance strategy for Low Critical item" guideline document is developed to define the best maintenance strategy for low critical units. All risks are evaluated using the standard ADNOC risk matrix. The risk is converted to monetary value in $ to evaluate maintenance actions using a formula. A special program was developed to facilitate MCA evaluation for each system and represent risk as monetary value using ADNOC Risk Matrix taking into consideration the redundancy and demand on a system during operation. MCAs were completed for all ADNOC Onshore Assets, see results below. Optimization starts by evaluating maintenance programs for low critical systems to save costs where low critical systems represent 50% to 60% of total systems in ADNOC Onshore. Based on this the total number of work orders has decreased by 6856, which is equivalent to saving $1M annually. In parallel, RCMs are conducted on high critical systems. Risk mitigation calculator in $ value was developed and embedded in the RCM information sheet to calculate cost benefit from implementing maintenance programs that were developed. RBMO is a systematic and traceable methodology to minimize maintenance cost and at the same time maximize system integrity and availability. This work showed the importance of reviewing the low critical systems’ maintenance program, as a first step in RBMO after implementing MCA, where low critical systems represent 50% to 60% of total assets and only 5% of total risks. ADNOC Onshore developed a dedicated guideline document "Maintenance Strategy for Low Critical Item" to facilitate decision making for proper maintenance strategy for low critical systems. Adding RCM risk mitigation calculator to RCM to calculate RCM cost benefit.

scholarly journals Study of acrylamide level in food from vending machines

2016 ◽  
Vol 5 (4) ◽  
Author(s):  
Naceur Haouet ◽  
Simona Pistolese ◽  
Raffaella Branciari ◽  
David Ranucci ◽  
Maria Serena Altissimi
Keyword(s):  
Human Exposure ◽  
High Performance ◽  
High Variability ◽  
Potato Chips ◽  
The Other ◽  
Bakery Products ◽  
Vending Machines ◽  
Public Areas ◽  
Protein Rich ◽  
The City

Acrylamide is a byproduct of the Maillard reaction and is potentially carcinogenic to humans. It is found in a number of foods with higher concentrations in carbohydrate-rich foods and moderate levels of protein-rich foods such as meat, fish and seafood. Acrylamide levels in food distributed in vending machines placed in public areas of the city of Perugia were analyzed by high-performance liquid chromatography. Samples included five different categories, depending on the characteristics of the products: 1) potato chips; 2) salted bakery products; 3) biscuits and wafers; 4) sweet bakery products; 5) sandwiches. A high variability in acrylamide level among different foods and within the same category was detected. Potato chips showed the highest amount of acrylamide (1781±637 μg/kg) followed by salted bakery products (211±245 μg/kg), biscuits and wafers (184±254 μg/kg), sweet bakery products (100±72 μg/kg) and sandwiches (42±10 μg/kg). In the potato chips and sandwiches categories, all of the samples revealed the presence of acrylamide while different prevalence was registered in the other foods considered. The data of this study highlight the presence of acrylamide in different foods sold in vending machines and this data could be useful to understand the contribution of this type of consumption to human exposure to this compound.

scholarly journals Protein supplements between consumer's opinion and quality control: an applied study in jordan

2019 ◽  
Vol 10 (3) ◽  
pp. 1961-1969
Author(s):  
Talal Aburjai ◽  
Rudaina Othman Yousif ◽  
Mahmood Jasim AlSamydai ◽  
Ali Al-Samydai ◽  
Farah Al-Mamoori ◽  
...  
Keyword(s):  
High Performance ◽  
Chromatographic Method ◽  
The Other ◽  
Primary Study ◽  
Fast Method ◽  
Reverse Phase ◽  
Protein Supplements ◽  
Sports Clubs ◽  
Applied Study ◽  
Other Substances

The consumption of dietary supplements has nowadays become popular, especially in Jordanian sports clubs and gyms. In fact, there is a widespread idea, among consumers, that these proteins contain hormones in order to increase their efficiency. The objective of this study is to develop a better understanding of customer opinion in an era that increased growth in Jordan and improves a chromatographic method to detect the testosterone in protein supplements. The method of this study, six popular types of proteins in the Jordan market have been chosen after conducting a primary study of the proteins' users by questionnaires to identify their opinions about these proteins. These proteins have been analyzed by reverse-phase high-performance liquid chromatography by developing an easy and fast method to detect testosterone signal between 8-9 minutes of the chromatogram. The results of the study showed that 61% of the users believe that sport proteins contain hormones and other substances that are not mentioned in the list of ingredients. While 39% believe otherwise. On the other side, HPLC results of six proteins showed no signs for testosterone hormone. The main reason that drives them to take sport proteins is for building muscles in spite of they believe it could be harmful due to containing hormones and other substances. So in future investigations, it might be possible to use different brands and investigate them by using the same method.

scholarly journals Analysis of Flavonoid Metabolites in Watercress (Nasturtium officinale R. Br.) and the Non-Heading Chinese Cabbage (Brassica rapa ssp. chinensis cv. Aijiaohuang) Using UHPLC-ESI-MS/MS

Molecules ◽  
2021 ◽  
Vol 26 (19) ◽  
pp. 5825
Author(s):  
Xiaoqing Ma ◽  
Qiang Ding ◽  
Xilin Hou ◽  
Xiong You
Keyword(s):  
Mass Spectrometry ◽  
Chinese Cabbage ◽  
High Performance ◽  
Reference Value ◽  
The Other ◽  
Tandem Mass ◽  
Nasturtium Officinale ◽  
Esi Ms ◽  
Heading Chinese Cabbage ◽  
Ionization Tandem Mass Spectrometry

Flavonoids from plants play an important role in our diet. Watercress is a special plant that is rich in flavonoids. In this study, four important watercress varieties were compared with non-heading Chinese cabbage by ultra-high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry (UHPLC-ESI-MS/MS). A total of 132 flavonoid metabolites (including 8 anthocyanins, 2 dihydroflavone, 3 dihydroflavonol, 1 flavanols, 22 flavones, 11 flavonoid carbonosides, 82 flavonols, and 3 isoflavones) were detected. Flavonoid metabolites varied widely in different samples. Both the non-heading Chinese cabbage and the variety of watercress from Guangdong, China, had their own unique metabolites. This work is helpful to better understand flavonoid metabolites between the non-heading Chinese cabbage and the other four watercress varieties, and to provide a reliable reference value for further research.

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