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 preli...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.展开更多
RLWI （Riserless Light Well Intervention） technology has the advantage of utilizing a special subsea lubricator to perform intervention activities in water depths of up to 1,200 m without the need for the marine rise...RLWI （Riserless Light Well Intervention） technology has the advantage of utilizing a special subsea lubricator to perform intervention activities in water depths of up to 1,200 m without the need for the marine risers. Utilizing the technology, oil companies have been able to save up to 50% on the intervention costs. However, in the last five years, it has seen up to 25% downtime due to waiting on weather （wow）. Thus, in this manuscript, it is attempted to identify the critical elements of the module deployment system and analyze their significance in the objective of raising the operational weather limit. Critical failure modes were found to be failure of crane wire due to excess loading, failure of the lower cursor system due to the impact loading and clashing of the module with the moonpool walls. Analysis of the module deployment system against these failure modes was ensued by using Orcaflex. The results showed the moonpool sea state to be the defining parameter. Although, changing moonpool dimensions affect hydrodynamics positively, however it＇s significance is small due to dependency on the vessel＇s breadth. Based on these results and the available data for the analysis, a recommended system particular was tested. Significance improvement, in lowering the risk of failure was observed.展开更多
In the literature, many works on determining inspection interval by the delay time concept generally assumed that the time of inspection span and the time of failure renewal are negligible. However, in realistic cases...In the literature, many works on determining inspection interval by the delay time concept generally assumed that the time of inspection span and the time of failure renewal are negligible. However, in realistic cases, the above time should not be neglected for both the time itself and its effect. In order to model the effect of the possible overlapping of inspection span with failure downtime on determining the optimal inspection interval, we propose a block-based inspection model for a single component-based on delay time concept. We further compare this model with the age-based model to show the practical sense. The developed models are also demonstrated by numerical examples.展开更多
Generally, lightning damage has mainly been to home appliances and telephones, towers and power transmission and generation equipment mal functions and damage due to strikes on power lines. With the adoption of wind p...Generally, lightning damage has mainly been to home appliances and telephones, towers and power transmission and generation equipment mal functions and damage due to strikes on power lines. With the adoption of wind power generation equipment, however, lightning damage is also increasing in this area. Through his dimensional characteristics, the wind power system is more exposed in the nature compared to all others systems. Lightning damage is the single largest cause of unplanned downtime in wind turbines, and that downtime is responsible for the loss of countless megawatts of power generation. The wind turbines are important structures, since they can easily attract the wrath of storms hits heights close, they can also capture the most distant. The rotation of the blades may also trigger lightning and result in considerable increase in the number of strikes to a wind turbine unit. Since wind turbines are tall structures, the lightning currents that are injected by return strokes into the turbines will be affected by reflections at the top, at the bottom, and at the junction of the blades with the static base of the turbine. We present our contribution in this paper to study lightning strokes and their effects on the wind turbines with the aim to enrich the work and to suggest more effective means of protection against lightning.展开更多
According to Brazilian reports of large trucks accidents on Federal Highway, fatigue and speeding are the major contributors to those accidents in which drivers are trying to meet short delivery deadlines for long hau...According to Brazilian reports of large trucks accidents on Federal Highway, fatigue and speeding are the major contributors to those accidents in which drivers are trying to meet short delivery deadlines for long hauls. A new federal law has been approved to limit truck drivers＇ working times, including maximum continuous driving time and maximum daily and weekly on-duty time. We present a study that aims at analyzing whether the existing resting areas on federal highways have sufficient capacity to meet current and future demand for truck stops. We have established the following method： In the first step, we review and study different models found in the literature and evaluate their potential application to Brazilian conditions; In the next step, we develop our own model and, finally, validate it using data from BR-101 Federal Highway, in Santa Catarina State. Tests made using part of collected data （which were subjected to statistical treatment） showed satisfactory results, indicating that the demand behavior was consistent with that observed in the field and the answers provided by truck drivers in the interviews. The research has yet to complete processing all data and it also must be repeated in other regions with different characteristics.展开更多
To evaluate the particle dynamics and estimate the POC (particulate organic carbon) export flux from the euphotic zone in the western Arctic Ocean,234 Th238 U disequilibrium was applied during the second Chinese Natio...To evaluate the particle dynamics and estimate the POC (particulate organic carbon) export flux from the euphotic zone in the western Arctic Ocean,234 Th238 U disequilibrium was applied during the second Chinese National Arctic Research Expedition (July 15-September 26,2003).The POC export fluxes are estimated from the measured profiles of the 234 Th/238 U activity ratios and the POC/PTh ratios.The average residence times of the particulate and dissolved 234 Th in the euphotic zone are 33 d and 121 d,and their average export fluxes are 480 dpm/m 2 d and 760 dpm/m 2 d,respectively.The scavenging and removal processes of particle reactive elements are active in the upper layer of the Chukchi Sea.The average residence time of 234 Th increases from shelf to basin,while the export fluxes of 234 Th decrease.The estimated POC export fluxes from the euphotic zone vary from 2.1 to 20.3 mmol/m 2 d,indicating that the western Arctic Ocean is an important carbon sink in summer due to efficient biological pump.展开更多
This paper studies for ward-back ward differential equations with Poisson jumps and with stopping time as termination. Under some weak monotonicity conditions and for non-Lipschitzian coefficients, the existence and u...This paper studies for ward-back ward differential equations with Poisson jumps and with stopping time as termination. Under some weak monotonicity conditions and for non-Lipschitzian coefficients, the existence and uniqueness of solutions are proved via a purely probabilistic approach, while a priori estimate is given. Here, we allow the forward equation to be degenerate.展开更多
Delirium is an acute and fluctuating change in mental status, with inattention and altered levels of consciousness. It is a common comorbidity in intensive care units （ICU）, resulting in delayed withdrawal of mechan...Delirium is an acute and fluctuating change in mental status, with inattention and altered levels of consciousness. It is a common comorbidity in intensive care units （ICU）, resulting in delayed withdrawal of mechanical ventilation, prolonged length of stay in ICU, increased ICU mortality and impaired long-term cognitive function of the survivors. Narcotic or psychoactive medication is one of the major risk factors that contribute to ICU delirium. Surveys conducted in several countries indicated that delirium in ICU was inad- equately monitored, underdiagnosed and lacked standardized treatment. In order to improve the prevention and treatment of ICU delirium, it is imperative that the ICU professionals should enrich their knowledge about this comorbidity, familiarize themselves with its screening and management, as well as standardize the administration of narcotic and psychoactive medications.展开更多
We consider a class of stochastic Boussinesq equations driven by L6vy processes and establish the uniqueness of its invariant measure. The proof is based on the progressive stopping time technique.
文摘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.
文摘RLWI （Riserless Light Well Intervention） technology has the advantage of utilizing a special subsea lubricator to perform intervention activities in water depths of up to 1,200 m without the need for the marine risers. Utilizing the technology, oil companies have been able to save up to 50% on the intervention costs. However, in the last five years, it has seen up to 25% downtime due to waiting on weather （wow）. Thus, in this manuscript, it is attempted to identify the critical elements of the module deployment system and analyze their significance in the objective of raising the operational weather limit. Critical failure modes were found to be failure of crane wire due to excess loading, failure of the lower cursor system due to the impact loading and clashing of the module with the moonpool walls. Analysis of the module deployment system against these failure modes was ensued by using Orcaflex. The results showed the moonpool sea state to be the defining parameter. Although, changing moonpool dimensions affect hydrodynamics positively, however it＇s significance is small due to dependency on the vessel＇s breadth. Based on these results and the available data for the analysis, a recommended system particular was tested. Significance improvement, in lowering the risk of failure was observed.
文摘In the literature, many works on determining inspection interval by the delay time concept generally assumed that the time of inspection span and the time of failure renewal are negligible. However, in realistic cases, the above time should not be neglected for both the time itself and its effect. In order to model the effect of the possible overlapping of inspection span with failure downtime on determining the optimal inspection interval, we propose a block-based inspection model for a single component-based on delay time concept. We further compare this model with the age-based model to show the practical sense. The developed models are also demonstrated by numerical examples.
文摘Generally, lightning damage has mainly been to home appliances and telephones, towers and power transmission and generation equipment mal functions and damage due to strikes on power lines. With the adoption of wind power generation equipment, however, lightning damage is also increasing in this area. Through his dimensional characteristics, the wind power system is more exposed in the nature compared to all others systems. Lightning damage is the single largest cause of unplanned downtime in wind turbines, and that downtime is responsible for the loss of countless megawatts of power generation. The wind turbines are important structures, since they can easily attract the wrath of storms hits heights close, they can also capture the most distant. The rotation of the blades may also trigger lightning and result in considerable increase in the number of strikes to a wind turbine unit. Since wind turbines are tall structures, the lightning currents that are injected by return strokes into the turbines will be affected by reflections at the top, at the bottom, and at the junction of the blades with the static base of the turbine. We present our contribution in this paper to study lightning strokes and their effects on the wind turbines with the aim to enrich the work and to suggest more effective means of protection against lightning.
文摘According to Brazilian reports of large trucks accidents on Federal Highway, fatigue and speeding are the major contributors to those accidents in which drivers are trying to meet short delivery deadlines for long hauls. A new federal law has been approved to limit truck drivers＇ working times, including maximum continuous driving time and maximum daily and weekly on-duty time. We present a study that aims at analyzing whether the existing resting areas on federal highways have sufficient capacity to meet current and future demand for truck stops. We have established the following method： In the first step, we review and study different models found in the literature and evaluate their potential application to Brazilian conditions; In the next step, we develop our own model and, finally, validate it using data from BR-101 Federal Highway, in Santa Catarina State. Tests made using part of collected data （which were subjected to statistical treatment） showed satisfactory results, indicating that the demand behavior was consistent with that observed in the field and the answers provided by truck drivers in the interviews. The research has yet to complete processing all data and it also must be repeated in other regions with different characteristics.
基金Supported by the National Natural Science Foundation of China (No.40531007)the China Action Plan of the International Polar Year (Nos.2009DFA22920 and 2008Po5040014-03)+1 种基金the International Science and Technology Cooperation (Nos. 2008DFA20420 and 2009DFA22920)the Polar Atmospheric Environment Remote Sensing Monitoring Technique of the National High Technology Research and DevelopmentProgram of China (863 Program) (No. N2008DFA20420)
文摘To evaluate the particle dynamics and estimate the POC (particulate organic carbon) export flux from the euphotic zone in the western Arctic Ocean,234 Th238 U disequilibrium was applied during the second Chinese National Arctic Research Expedition (July 15-September 26,2003).The POC export fluxes are estimated from the measured profiles of the 234 Th/238 U activity ratios and the POC/PTh ratios.The average residence times of the particulate and dissolved 234 Th in the euphotic zone are 33 d and 121 d,and their average export fluxes are 480 dpm/m 2 d and 760 dpm/m 2 d,respectively.The scavenging and removal processes of particle reactive elements are active in the upper layer of the Chukchi Sea.The average residence time of 234 Th increases from shelf to basin,while the export fluxes of 234 Th decrease.The estimated POC export fluxes from the euphotic zone vary from 2.1 to 20.3 mmol/m 2 d,indicating that the western Arctic Ocean is an important carbon sink in summer due to efficient biological pump.
文摘This paper studies for ward-back ward differential equations with Poisson jumps and with stopping time as termination. Under some weak monotonicity conditions and for non-Lipschitzian coefficients, the existence and uniqueness of solutions are proved via a purely probabilistic approach, while a priori estimate is given. Here, we allow the forward equation to be degenerate.
文摘Delirium is an acute and fluctuating change in mental status, with inattention and altered levels of consciousness. It is a common comorbidity in intensive care units （ICU）, resulting in delayed withdrawal of mechanical ventilation, prolonged length of stay in ICU, increased ICU mortality and impaired long-term cognitive function of the survivors. Narcotic or psychoactive medication is one of the major risk factors that contribute to ICU delirium. Surveys conducted in several countries indicated that delirium in ICU was inad- equately monitored, underdiagnosed and lacked standardized treatment. In order to improve the prevention and treatment of ICU delirium, it is imperative that the ICU professionals should enrich their knowledge about this comorbidity, familiarize themselves with its screening and management, as well as standardize the administration of narcotic and psychoactive medications.
基金supported by National Natural Science Foundation of China (Grant Nos.10971225 and 11101427)Natural Science Foundation of Hunan Province (Grant No. 11JJ3004)the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State the Ministry of Education of China
文摘We consider a class of stochastic Boussinesq equations driven by L6vy processes and establish the uniqueness of its invariant measure. The proof is based on the progressive stopping time technique.
