Liquefaction Research Articles

Evaluation Methods of Cyclic Shear Stress Ratio for the Assessment of Liquefaction in Korea

Evaluation Methods of Cyclic Shear Stress Ratio for the Assessment of Liquefaction in Korea

Numerical Simulation of Multi-component Lng Pool Fire

The release of large amount of liquefied natural gas from fixed or mobile equipment may induce to pool fire when immediate ignited. The prediction and simulation of this phenomenon is very complex because several premixed, convective and diffusive burning phenomena, and rapid phase evaporation, are involved simultaneously. Nevertheless, the use of Reynolds-averaged Navier-Stokes (RANS) equations with k-e model for turbulence and classical models are still adopted, although strong uncertainties and over-simplifications with respect to the real scenario. More recently large-eddy simulation (LES) modeling, as adopted in some codes as FLUENT or FDS, has been adopted. LES methodology is able to introduce more detailed information on the chemical kinetic of the oxidation reactions. Again, however, poor kinetic combustion mechanisms suitable for the implementation in computational fluid dynamic (CFD) codes, and simplified composition for the LNG - often treated as pure methane - are typically adopted. In this work, the simulation of a LNG pool fire was performed by detailed (reduced) kinetic model validated for multi-component LNG compositions by using FDS. Results were compared with both experimental and numerical analyses retrieved from literature. This approach has the potential to correctly estimate the heat radiation and the production rates of the main reaction products, including soot.

Toward a numerical-simulation-based liquefaction hazard assessment for urban regions using high-performance computing

Effective and efficient liquefaction hazard assessment is critical in making disaster mitigation plans for urban regions. In this paper, we present a numerical-simulation (NS)-based method for assessing urban-wide liquefaction hazard. The method includes an automatic modelling for individual sites and an application of high-performance computing (HPC) for efficient assessment. The feasibility of the method is demonstrated by conducting simulations for more than 10,000 individual sites in an urban region. The urban-wide assessment results depend on a pressure threshold of liquefaction occurrence and the dependence increases as the ground motion increases. A comparison with a conventional method using engineering indices (EI) shows a tendency of the EI-based method to predict a considerably greater number of liquefied sites than the proposed method. With the continuing improvement on numerical simulations and on computer efficiency, NS-based assessments can be regarded as promising alternatives to conventional EI-based methods for urban-wide liquefaction assessment.

Application of customized variable-angle locking acetabular wing plates in treatment of acetabular fractures in the elderly via the lateral-rectus approach

Objective To evaluate clinical efficacy and surgical techniques of customized variable-angle locking acetabular wing plates in treatment of complex acetabular fractures in the elderly through the lateral-rectus approach. Methods Data of 11 elder patients of complex acetabular fractures (mean age 75 y, range: 60-93 y; 8 males, 3 females) admitted to our department from March 2016 to March 2017 were retrospectively analyzed. According to Judet-Letournel classification of acetabular fractures, there were 2 cases of anterior column and posterior hemitransverse fractures, 9 cases of both-column fractures. The customized variable-angle locking acetabular wing plates were designed by mimics software and then produced before surgery. During the operation, the customized variable-angle locking acetabular wing plate was applied to reduction and fixation via the anterior lataral-rectus approach. The effect of fracture reduction was assessed by Matta's criteria. The clinical effect was assessed by Harris Hip score and the modified Merle d' Aubigne-Postal score at the 6th month of postoperative follow-up. Results The average time of designing and producing customized variable-angle locking acetabular wing plates was 4 d (3-5 d), the average operation time was 95 min (45-150 min), and the average intraoperative bleeding was 600 ml (250-1 400 ml). All patients were followed up, with an average follow-up of 18 m (6-24 m). All fractures were healed, with an average healing time of 8 weeks (6-12 weeks). Reduction quality: excellent in 8 cases, good in 2 cases, poor in 1 case, with an overall excellent and good rate of 90.9%. The result of Harris Hip scoring: excellent in 7 cases, good in 3 cases, and acceptable in 1 case, with a total excellent and good rate of 90.9%; Modified Merle d' Aubigne-Postal soring: excellent in 6 cases, good in 3 cases, and acceptable in 2 cases, with an overall excellent and good rate of 81.8%. There were 2 cases of obturator nerve injury, 1 case of fat liquefaction of incision, 3 cases of traumatic hip arthritis. During the follow-up, no complications such as ectopic ossification, plate fracture and screw loosening were found. Conclusion The customized variable-angle locking acetabular wing plates in treatment of complex acetabular fractures in the elderly via the lateral-rectus approach can achieve satisfactory reduction and firm fixtation. Key words: Acetabulum; Fracture; Aged; Fracture fixation, internal

Factors of fat necrosis after breast reconstruction with autologous fat graft

Objective To investigate the related factors of fat necrosis nodules after autologous fat grafting for breast reconstruction. Methods Different methods of purification, number of operations, and history of breast radiation were analyzed. The relationship between fat graft and necrosis were compared. A total of 48 patients undergoing autologous transplantation for breast reconstruction after radical mastectomy between January 2015 and June 2017 in Chinese Academy of Medical Sciences were retrospectively analyzed, and 51 breasts were used. Results After surgery, 9 cases of palpable nodules were found in the breast, including 8 cases in the centrifuge group and 1 case in the sedimentation group. There were 20 cases of multiple hypoechoic nodules in breast ultrasound, including 13 cases in the centrifugation group and 7 cases in the sedimentation group. The incidence of breast nodules in the centrifuge group was 33.33%, and the incidence of fat liquefaction cysts was 54.17%; the incidence of breast nodules in the sedimentation group was 3.7%, and the incidence of fat liquefaction cysts was 25.93%. In this study, there were 4 cases of breast fat filling surgery, 18 cases of fat graft for 2 times, 23 cases of breast fat filling for 3 times, and 6 cases of fat filling for 4 times; the more time of fat graft surgery, the higher of the fat necrosis incidence. There were 21 cases of breasts with radiotherapy history, 30 cases of breast without radiotherapy history, 7 cases of nodules after autologous fat transplantation and breast reconstruction in radiotherapy group, 2 cases of nodules that could be touched after autologous fat transplantation without breast reconstruction, and 2 cases with radiotherapy. The incidence of fat necrosis after fat transplantation breast reconstruction was higher than those without radiotherapy. Conclusions The incidence of fat necrosis after fat-purified with centrifugation autologous grafting for breast reconstruction is higher than that by sedimentation method. The higher rate of fat necrosis is observed after breast reconstruction with autologous fat grafting in radiotherapy than that without radiotherapy. Key words: Adipocytes; Transplantation; Fat necrosis; Nodules; Breast reconstruction

Host modulation therapy- An innovative paradigm in dentistry

Inflammation comprises a series of events that leads to a host response against trauma and microbial invasion, resulting in liquefaction of surrounding tissues to prevent microbial metastasis, and eventually to healing of injured tissue compartments. Thus, by definition, the host response involves not only the mechanisms of defence but also processes of repair of damage that occurs by the direct effect of invaders or trauma or host systems. Periodontal diseases are inflammatory processes in which microbial etiologic factors induce a series of host responses that mediate an inflammatory cascade of events in an attempt to protect and heal the periodontal tissues. The adjunctive use of host modulation therapy can enhance therapeutic responses, slow the progression of the disease, and allow for more predictable management of patients, particularly in those patients at increased risk caused by factors beyond the reach of conventional therapeutic approaches. Key words: Host modulation, NSAIDs, Bisphosphonates, immune-inflammatory response, MMPs

The research progress of urokinase in central nervous system

Urokinase is one of the main activators of plasminogen. It has been a hot topic in recent years. According to the role of urokinase in pathological and physiological processes, it has been applied in many clinical fields, such as cancer treatment, vascular recanalization, tissue repair and so on. Urokinase has been widely used in neurology, including thrombolysis and minimally invasive puncture of intracranial hematoma as liquefying agent of hematoma. This article reviews the research progress of urokinase in central nervous system. Key words: Urokinase; Central nervous system; Research progress

Analysis of clinical effect on 19 cases of inguinal hernia treated by laparoscopic totally extraperitoneal repair

Objective To investigate the effect of laparoscopic total extraperitoneal tension-free hernia repair (TEP) in the treatment of inguinal hernia with absorbable biological mesh. Methods A retrospective analysis of the clinical data of 19 patients with inguinal hernia with biological mesh was performed from September 2015 to September 2016 in Shengjing Hospital of China Medical University. The average operative time, average incision pain time, average postoperative venting time, average hospital stay, average operative cost, and long-term chronic pain, postoperative complications, and recurrence rate were observed. Results All the 19 patients were successfully operated. The average operation time was (35.0±4.0) min, the average incision pain time was (1.5±0.6) d, and the average postoperative venting time was (1.5±1.2) d. The average hospital stay was (4.5±0.9) d, the average surgery cost was (23 534.6±1 259.9) yuan. Two patients developed swelling of the scrotum after surgery, and one patient developed postoperative fat liquefaction. All patients were followed up for 1 year by telephone, with no recurrence, no serious complications, and chronic pain discomfort. Conclusions The application of absorbable biopsy TEP is a good and reliable way to treat inguinal hernia. Postoperative patients have mild pain and low complication rate. There is no recurrence in recent follow-up, and the short-term effect is satisfactory. It is a reliable method for the treatment of inguinal hernia. The cost is high, and can be selected according to age and individual needs. Key words: Hernia, inguinal; Laparoscopes; Laparoscopic totally extraperitoneal repair; Biological mesh; Tension-free repair

Application of reconstruction of submammary fold with lateral thoracic wall adipofascial flap after nipple-areola complex sparing mastectomy in elderly breast cancer

Objective To evaluate the value of reconstruction of submammary fold with lateral thoracic wall adipofascial flap after nipple-areola complex sparing mastectomy(NSM) in elderly patients with breast cancer. Methods To retrospective analysis 20 cases of elderly patients with breast cancer were admitted from March 2016 to June 2018 in Beijing Tongren Hospital, Capital Medical University using reconstruction of submammary fold with lateral thoracic wall adipofascial flap after NSM(study group). Twenty-two elderly patients with breast cancer who had breast-conserving and sentinel lymph node biopsy were selected as control group. The operation time, drainage tube retention time, postoperative hospitalization time, postoperative complications, breast contour satisfaction were statistically analyzed. The measurements were expressed as mean±standard deviation (Mean±SD), and t-test was used for inter-group comparison, and Chi-square test was used for inter-group comparison of counting data. Results All cases were followed up for 3-27 months without local recurrence and distant metastasis. The difference in operative time between the study group and control group was statistically significant [(2.085±0.163 1) h vs (1.918±0.159 3) h, P=0.002]. There was no significant difference between the study group and control group in drainage tube removal time(5.25±0.910) d vs (5.27±0.767) d, hospitalization days(6.25±0.910) d vs (6.27±0.767) d, breast contour satisfaction rate (90.0% vs 81.8%) (P>0.05). Postoperative necrosis and liquefaction of adipofascial flaps occurred in 1 case in the study group and delayed healing occurred. Conclusion For some early-stage elderly breast cancer, reconstruction of submammary fold with lateral thoracic wall adipofascial flap after NSM, at the same time of radical surgery, can ensure the basic breast shape, avoid the chest wall deformity caused by traditional radical mastectomy, and improve the appearance and quality of life after mastectomy. Key words: Aged; Breast neoplasms; Lateral thoracic wall adipofascial flap; Reconstruction of submammary fold

Investigation of the liquefaction potential of fiber-reinforced sand

In the present, the liquefaction potential of fiber-reinforced sandy soils was investigated through the energy-based approach by conducting a series of strain-controlled cyclic simple shear tests. In the tests, the effects of the fiber properties, such as the fiber content, fiber length, relative density and effective stress, and the test parameters on sandy soil improvement were investigated. The results indicated that the fiber inclusion yields to higher cumulative liquefaction energy values compared to the unreinforced (plain) ground by increasing the number of cycles and shear strength needed for the liquefaction of the soil. This result reveals that the fiber inclusion increases the resistance of the soil to liquefaction. However, the increase in the fiber content was determined to be more effective on the test results compared to the fiber length. Furthermore, the increase in the relative density of the soil increases the efficiency of the fibers on soil strengthening.

Physical modelling of soil liquefaction in a novel micro shaking table

The physical models are useful to understand the soil behaviour. Hence, these tools allow validating analytical theories and numerical data. This paper addresses the design, construction and implementation of a physical model able to simulate the soil liquefaction under different cyclic actions. The model was instrumented with a piezoelectric actuator and a set of transducers to measure the porewater pressures, displacements and accelerations of the system. The soil liquefaction was assessed in three different grain size particles of a natural sand by applying a sinusoidal signal, which incorporated three amplitudes and the fundamental frequencies of three different earthquakes occurred in Colombia. In addition, such frequencies were scaled in a micro shaking table device for 1, 50 and 80 g. Tests allowed identifying the liquefaction susceptibility at various frequency and displacement amplitude combinations. Experimental evidence validated that the liquefaction susceptibility is higher in the fine-grained sands than coarse-grained sands, and showed that the acceleration of the actuator controls the phenomena trigging in the model instead of the displacement amplitude.

Liquefied Natural Gas (LNG): Prospects and Opportunities for Qatar in Sub-Saharan Africa

Liquefied Natural Gas (LNG) is a critical source of energy at the global level. Its potential, opportunities, challenges, and prospects vary greatly from a regional and national perspective and could evolve on the short or medium term. This paper analyses the LNG sector in Qatar and in sub-Saharan Africa within a global perspective to highlight openings and advantages for Qatar. It emphasizes that, under precise conditions, LNG is a promising domain in number of African countries, especially those who are gas producers. Qatar could benefit from LNG investment and skill transfer in Africa, using the sector as an entry point for strategic partnerships with African stakeholders and countries, showing encouraging promises. Qatar could take the lead among Gulf countries and contribute to support socio-economic development in Africa, with consequent direct and indirect benefits for its geopolitical role in the Arabic world and beyond.

Field application of freezing technology for social infrastructures

There are numerous methods to prevent seepage flow and ground improvement methodologies such as cement grouting, sheet piling, and the membrane method. In this paper, we present case histories of freezing technology applications in the construction of a deep tunnel sewerage system, undersea highway tunnel, and liquefied natural gas tank. Heaving pressure measurements for various soil types around a liquefied natural tank are compared with existing data. In this paper, we present temperature variations at the bottom and side of a liquefied natural gas tank. Our findings show that ground-freezing technology is very effective in controlling ground water infiltration into underground structures as well providing soil reinforcement in the soft ground.

Continuous Measurement of Odorant Composition for Liquefied Petroleum Gas

In Chile, commercial liquefied petroleum gas (LPG) is customarily odorized with dimethyl sulfide (DMS) and tert-butyl mercaptan (TBM) at a rate of about 10 grams of odorant per 1 cubic meter of LPG. The current control of the odorization practice involves the human nose to detect the odor in some cases, and the determination of total sulfur concentration in others. None of those methods provide the speciation of the sulfur species in LPG.On the other hand, both DMS and TBM are higher boiling than propane or butane. Therefore, the odorant concentration emanating from the odorized liquid is not uniform in the vapors released. Furthermore, the gas will also be much leaner than the odorized liquid. For those reasons, the Chilean industry recommends analyzing the odorant directly from the liquid phase.To address the problem of odorant quantification at the industry this research aims to develop a reliable and objective measure for odorized LPG that allow not only verify the odorization itself but also quantify the species incorporated with the fuel, and other sulfur compounds present naturally in the LPG. In this regard, an Automated Gas Chromatograph (Auto-GC) with an electrochemical detector was coupled with an LPG valve, which continuously takes samples of 1 µL of liquid propane. The extracted sample is then vaporized and injected into the Auto-GC to be analyzed.The methodology is capable of distinguishing and quantifying distinct odorants near real-time (within 8 minutes), as well as other sulfur impurities present in the LPG such as tetrahydrothiophene (THT) and methyl mercaptan (MeSH). Typical retention times for TBM and DMS corresponded to 282 s and 418 s respectively. More importantly, the proposed method provides meaningful information to verify the optimum odorization, i.e., the minimum value to alert in case of leak and maximum level that assures efficient combustion.

소형 선박용 극저온 액화가스 저장탱크 설계 기초 연구

소형 선박용 극저온 액화가스 저장탱크 설계 기초 연구

Safety of Dangerous Goods Transportation by Road: a Comparison Between QRAM and GIIS Software

The aim of the work is to develop a comparison between two software able to assess the risk associated with the transport of goods by road: QRAM - Quantitative Risk Assessment Model and GIIS – Global Integrated Information System, implemented within the DESTINATION project - DangErous tranSport To New prevenTive Instruments.It was thus possible to verify if the outputs obtained with the two software are comparable, although the two analytic models are widely different.The analysis included two comparisons, a and s: the former considers road users as targets and two accident scenarios, i.e. the petrol pool fire and the Liquefied Petroleum Gas (LPG) jet fire. The latter concerns three accident scenarios, i.e. the petrol and LPG Vapor Cloud Explosion (VCE) and the ammonia release. In this case, road users and population are taken into consideration as targets: residents, industry workforce, tourists and staff of commercial, health and education facilities.The assessment was carried out on different types of road: highway, state road and provincial roads, in order to study the functioning of the two models with different traffic conditions and exposed population (targets) surrounding the road links.

CFD Modelling of Vertical LNG Tanks Adopted in Heavy Trucks Refuelling Stations

In the present study, a Computational Fluid Dynamics (CFD) model was set up to analyse the dynamic behaviour of LNG (Liquefied Natural Gas) tanks adopted in heavy trucks refuelling stations in normal operating conditions or during process upsets. The CFD model was based on the Volume-Of-Fluid (VOF) method to simulate the transient behaviour of a multi-phase flow in a 100 m3 vertical cylindrical tank. The model first considered a fully insulated vessel, and subsequently it was modified to take into account possible damages of the insulation layer, this being a critical upset scenario. The CFD model allowed predicting the dynamic pressure build up in the damaged tank, thus obtaining key indications for the evaluation of the vessel mechanical resistance and set up of safety measures. The model also provided the prediction of vapor temperature with respect to time and external heat source, that is a key issue to assess the effectiveness of the thermal insulation.

Inherent Safety Assessment of LNG Fuelled Ships and Bunkering Operations: a Consequence-based Approach

Liquefied natural gas (LNG) is becoming a viable, environmental-friendly alternative to marine fuel oil for ship propulsion. However, LNG flammability induces relevant safety concerns due to fire and explosion hazards. The present contribution is aimed at the safety assessment of onshore bunkering configurations for marine fuel systems, with particular reference to LNG technologies. A specific review of bunkering methods, including connection to the ship fuel system, is carried out to provide a knowledge background. Moreover, the conventional process configurations based on intermediate fuel oil (IFO) are taken into account for a comparison between process alternatives. A consequence-based approach is followed to develop a set of key performance indicators aimed at evaluating and comparing the inherent safety of LNG and IFO systems. The results obtained allow for a clear identification of critical process units and operations, indicating that conventional IFO bunkering is inherently safer when compared to LNG. Therefore, safety aspects need to be balanced with environmental benefits, in the perspective of sustainable development of LNG supply chain for marine applications.

Liquefaction of Lignocelluloses as a Promising Alternative to Petrochemicals

Liquefaction of Lignocelluloses as a Promising Alternative to Petrochemicals

Clinical and pathological analysis of three cases of lichen planopilaris

Objective To investigate clinical and histopathological features of lichen planopilaris (LPP) . Methods The clinical and histopathological findings in 3 cases of LPP were analyzed. Results All the 3 patients were female, and their average age was 49 years. One patient presented with large-area patchy hair loss on the frontal, parietal and occipital region, and 2 patients presented with irregular patchy hair loss on the scalp and skin atrophy. Besides the hair loss, the eyebrows and axillary hairs also lost in 1 patient. Histopathological examination showed liquefaction degeneration of basal cells in the walls of hair follicles and infiltration of lymphocytes. Infiltration of a small number of lymphocytes was also observed around blood vessels and appendages. Conclusions LPP may only affect the scalp, or involve the other sites all over the body. LPP commonly manifests as patchy hair loss on the scalp and skin atrophy, and is pathologically characterized by liquefaction degeneration of basal cells in hair follicles and infiltration of lymphocytes. Key words: Lichen planus; Hair; Hair follicle; Alopecia