The Recording and Analysis of Downtime in Processing Enterprises

The paper discusses the importance of recording and analyzing downtime in processing enterprises, and takes Shanghai Mila Brew Company Limited as the example to analyze the problems in recording and analyzing downtime. Finally, suggestions of improvement are given out.

Evidence for self-organized criticality in unscheduled downtime data of equipment

How to reduce downtime and improve availability of the complex equipment is very important. Although the unscheduled downtime（USDT） issues of the equipment are very complex, the self-organized criticality（SOC） is the right theory to study complex systems evolution and opens up a new window to the investigation of disasters, such as the sudden failure of the equipment. Firstly,SOC theory and its validation method are introduced. Then an SOC validation method for USDT of the equipment is proposed based on the above theory. Case study is done on bottleneck equipment in a factory and corresponding data pre-process work is done. The rescaled-range（R/S） analysis method is used to calculate the Hurst exponent of USDT time-series data in order to determine the long-range correlation of USDT data on time scale;at the same time the spatial power-law characteristic of USDT time series data is studied. The result shows that the characteristics of SOC are revealed in USDT data of the equipment according to the criterion of SOC. In addition, based on the characteristics of SOC,the overall framework of the prediction method for major sudden failure of the equipment is proposed based on SOC.

Preliminary Assessment of Operational Downtime of Sea Ports and Berthing Facilities through Numerical Modelling

Downtime due to adverse wave conditions for vessels at berth is an important commercial aspect in the planning and development of a sea port or a berthing terminal. This paper describes a practical technique for preliminary assessment of operational downtime at a proposed bulk terminal. Time-series wind and wave data at an offshore location was purchased. Numerical modelling was then carried out using the MIKE21 SW （spectral wave） model developed by DHI （Deutsches Hydrographisches Institut） to transform these offshore waves into inshore in order to derive wave conditions at the berth. Both wind-waves and swell-waves were considered. Waves affecting the head and beam of a vessel were considered separately for a wide range of vessel sizes with DT （displacement tonnage） ranging from 5,000 tons to 〉 200,000 tons. The limiting wave height H5% was used. Operational downtime was also calculated using significant wave height, Hs as a criterion with limits ofHs = 1.0 m for beam seas and Hs = 1.5 m for head seas. The methodology and lessons learnt from the study can be applied for the development of any sea port worldwide.

Fuzzy-based approach to quantify the downtime of buildings in developing countries

Earthquake is one of the natural disasters that affects the buildings and communities in developing countries.It causes different levels of damages to the buildings,making them uninhabitable for a period of time,called downtime(DT).This paper proposes a Fuzzy Logic hierarchical method to estimate the downtime of residential buildings in developing countries after an earthquake.The use of expert-based systems allows quantifying the indicators involved in the model using descriptive knowledge instead of hard data,accounting also for the un-certainties that may affect the analysis.The applicability of the methodology is illustrated using the information gathered after the 2015 Gorkha,Nepal,earthquake as a case study.On April 25,2015,Nepal was hit by the Mw 7.8 Gorkha earthquake,which damaged and destroyed more than 500.000 residential buildings.Information obtained from a Rapid Visual Damage Assessment(RVDA)is used through a hierarchical scheme to evaluate the building damageability.Sensitivity analysis based on Sobol method is implemented to evaluate the impor-tance of parameters gathered in the RVDA for building damage estimation.The findings of this work may be used to estimate the restoration time of damaged buildings in developing countries and to plan preventive safety measures.

Influence rule of downtime on heat transfer in converters

The models for calculating the heat transfer in converters allow the accurate control of heat dissipation caused by downtime,and thus help in crease scrap ratio and reduce energy consumptio n.ANSYS 17 was used to establish such a model to analyse the coupling law between the downtime and heat dissipation of the converter and the temperature drop of molten iron.Temperature was measured by infrared detection,and model accuracy was verified by comparative analysis.The variation law of the amount of cold charge added for different downtimes under different process conditions was studied.The results show that the range of the variation of heat dissipation caused by downtime is 8.9-78.5 GJ.If the downtime increases by 30 min,heat dissipation of dephosphorisation(deP)and decarburisation(deC)converters increases by about 23.4 and 41.3 GJ,respectively.In a certain smelting cycle,the temperature drop of the molten iron for deP,deC and conventional converters increases by about 12.5,15.0 and 17.0 K,respectively;and the amount of scrap added in the double-linking and conventional smelting processes decreases by 0.93 and 0.75%,respectively.

Moored Ship Motions due to Tropical Cyclone Linda

Severe wind-wave due to tropical cyclone Linda can cause port downtime which affects port operations such as berthing, mooting and （un）loading of the ship. The ship motions are criteria for limiting the port operations, human safety and preventing the damage of port equipment and furniture. Therefore, this study discusses moored ship motions due to severe wind-wave during the tropical cyclone Linda which entered the Gulf of Thailand in November 1997. The ship motions are represented in the moored ship analysis at SRH （Sriracha Harbour Port） and BLCP （BLCP Coal-Fired Power Plant Port）, and are subject to the static environmental load on the ship in accordance with Spanish Standard （ROM 0.2-1990） [1]. The environment in numerical model is derived from the wave model and hydrodynamics model using the application of Delft3D-WAVE and Delft3D-FLOW. The model location includes Ao Udom Bay and Rayong Sea. The model results represent the environment at Rayong Sea which is more severe than Ao Udom Bay. The ship motions at BLCP are mostly larger than SRH.

Some Reliability Problems Arising in the M^x/G(M/G)/1 Repairable Queueing System with Single Delay Vacation

On the basis of Ref.\, the M x/G(M/G)/1 repairable queueing system with single delay vacation is discussed again. The following reliability problems of the service station are studied: (a) The probability that it fails at time t , i.e. its unavailability; (b) The expected failure number during the time interval (0,t\];; (c) The expected failure number during the ″server busy period″; (d) The expected downtime during the time interval (0,t\]. Some reliability results of the service station are obtained. These results would be interest to reliability analysts.

Dynamic trip point categorisation using manufacturing process for polycrystalline diamond compact bits as case study

Disruptions in the manufacturing process cast substantial impacts on the consumer’s centric values,cost,and overall efficiency.The ripple effect of these disruptions is observed in the whole assembly line.The proper analysis and mitigation of disruptions is the key to the proficiency of the plant and resource utilisation.The research focuses on the quantitative analysis of the impact of disruptions of the manufacturing process,which is performed by analysing the disruptive workstation dynamically.The disruptive workstations have a significant impact on succeeding and preceding workstations,which have been analysed dynamically,and accordingly,the preset alarm trip points are elevated.The results show that lowering the number of starts and stops decreases the number of rejections of valuable process batches that finally improve efficiency.Finally,the developed model is implemented on a polycrystalline diamond compact drill bit manufacturing plant.The results are compared with the research work of other researchers,showing a 60%reduction in the number of start/stop events,60%reduction in downtime,while a 75%reduction in the number of rejections is noted.