The micro-riblet structures have been demonstrated effective in controlling the Total Pressure Loss(TPL)of aero-engine blades.However,due to the considerable scale gap between micro-texture and an actual aero-engine b...The micro-riblet structures have been demonstrated effective in controlling the Total Pressure Loss(TPL)of aero-engine blades.However,due to the considerable scale gap between micro-texture and an actual aero-engine blade,wind tunnel tests and numerical simulations with massive grids directly describing the global flow field are costly for aerodynamic evaluation.Furthermore,the fine micro surface structure brings unavoidable manufacturing errors,and the probability prediction contributes to gaining the confidence interval of the results.Therefore,a novel relay-based probabilistic model for multi-fidelity scenarios in the TPL prediction of a compressor cascade with micro-riblet surfaces is proposed to trade off accuracy and efficiency.Combined with the low-fidelity flow data generated by an aerodynamic solution strategy using the boundary surrogate model and the high-fidelity flow data from the experiment,the relay-based modeling has been achieved through knowledge transferring,and the confidence interval can be provided by the Gaussian Process Regression(GPR)model.The TPL of compressor cascades with micro-riblet surfaces under different surface structures at March number Ma=0.64,0.74,0.84 have been evaluated using the Relay-Based Probabilistic(RBP)model.The results illustrate that the RBP model could provide higher accuracy than the Single-Fidelity-Data-Driven(SFDD)prediction model,which show the promising potential of multi-fidelity scenarios data fusion in the aerodynamic evaluation of multi-scale configurations.展开更多
No-insulation(NI)coils emerged as a viable alternative to traditional insulated(INS)high temperature super-conducting(HTS)coils primarily due to their inherent ability to self-protect during quench and enhanced me-cha...No-insulation(NI)coils emerged as a viable alternative to traditional insulated(INS)high temperature super-conducting(HTS)coils primarily due to their inherent ability to self-protect during quench and enhanced me-chanical stability.When coils carrying direct current(DC)are exposed to an external alternating current(AC)magnetic field,total loss in the coil is the sum of magnetisation loss due to the AC field and dynamic loss arising from the interaction between the DC current and the AC field.In this work,we numerically study the total loss and its components in NI and INS double-pancake coils(DPCs)of identical dimensions,wound with 4 mm wide SuperPower Rare-earth barium copper oxide(ReBCO)coated conductor(CC)tapes at 77 K.The analysis is carried out for external AC magnetic fields up to 200 mT at 72.73 Hz,with the coil carrying DC current up to 90%of the coil self-field critical current.The results show that under a perpendicular magnetic field,the total loss and its components in the INS-DPC are higher than in the NI-DPC,which is attributed to the presence of insu-lation which hinders the current bypass.The NI-DPC and INS-DPC coils show similar electromagnetic behaviour under the perpendicular field,and the evolution of dynamic resistance,which gives rise to dynamic loss,is also similar.Under parallel field the loss in the NI-DPC is higher than that for the perpendicular field,and the coil level shielding similar to bulk superconductor is also observed.Surprisingly,under parallel fields,a dynamic resistance higher than that under perpendicular fields is evident in the NI-DPC,arising from a finite average electric field over a cycle.展开更多
REBCO tapes carry DC current under AC magnetic fields in proposed HTS fusion applications. AC loss will be generated in the process and it is important to understand the AC loss behaviour for safe operation of the fus...REBCO tapes carry DC current under AC magnetic fields in proposed HTS fusion applications. AC loss will be generated in the process and it is important to understand the AC loss behaviour for safe operation of the fusion magnets. In this work, magnetisation loss (Qm), dynamic resistance (Rdyn), and total loss (Qtotal) in four different REBCO tapes are numerically studied, using the measured and , for the magnetic field amplitude applied perpendicularly up to 8 T at 20 K and 50 K, where represents the magnetic field and field angle () dependent critical current density. The peak of Theva data is different from that of other tapes. We artificially shifted the ab-plane peak of Theva to the left by 25° to match the peak value. The newly shifted data is named as Theva-shift, which was also investigated to study the influence of the Theva peak shift on AC loss. The normalised DC transport current level (i = It/Ic0) ranges from 0.05 to 0.9, where the DC current amplitude and the self-critical current of the tape are represented by It and Ic0, respectively. The simulation results show that the AC losses deviate significantly from the Brandt-Indenbom (BI) equation at high magnetic fields. Jc and instantaneous loss curves for different tapes show correlation at high magnetic fields. The simulation results also show how different characteristics for different tapes influence AC losses. When AC loss values are scaled by the self-field critical current, Qm without current and Qtotal with current in the different tapes show a good agreement. It implies that the temperature dependence of the two types of loss can be calculated from a known loss at one temperature and the self-field critical current.展开更多
AIM To investigate the total blood loss(TBL) and the safety with respect to the re-amputation rate after transtibial amputation(TTA) conducted with and without a tourniquet. METHODS The study was a single-centre retro...AIM To investigate the total blood loss(TBL) and the safety with respect to the re-amputation rate after transtibial amputation(TTA) conducted with and without a tourniquet. METHODS The study was a single-centre retrospective cohort study of patients with a primary TTA admitted between January 2013 and April 2015. All patients with a primary TTA were assessed for inclusion if the amputation was performed because of arteriosclerosis or diabetic complications. All patients underwent a standardized TTA procedure that was performed approximately 10 cm below the knee joint and performed with sagittalflaps. The pneumatic tourniquet, when used, was inflated around the femur to a pressure of 100 mmH g above the systolic blood pressure. The number of blood transfusions within the first four postoperative days was recorded. The intraoperative blood loss(OBL), which is defined as the volume of blood lost during surgery, was determined from the suction volume and by the weight difference of the surgical dressings. The trigger for a blood transfusion was set at a decrease in the Hgb level < 9.67 g/dL(6 mmol/L). Transfusions were performed with pooled red blood cells containing 245 m L per portion, which equals 55 g/L of haemoglobin. The TBL during the first four postoperative days was calculated based on the haemoglobin level and the estimated blood volume. The re-amputation rate was evaluated within 30 d. RESULTS Seventy-four out of 86 consecutive patients who underwent TTA within the two-year study period were included in the analysis. Of these, 38 were operated on using a tourniquet and 36 were operated on without using a tourniquet. There were no significant preoperative differences between the groups. The patients in both groups had a postoperative decrease in their Hgb level compared with preoperative baseline values. The patients operated on using a tourniquet received approximately three millilitres less blood transfusion per kilogram body weight compared with patients operated on without a tourniquet. The duration of surgery was shorter and the OBL was less for the tourniquet group than the non-tourniquet group, whereas no significant difference was observed for the TBL. The TBL median was 859 mL(IQR: 383-1315) in the non-tourniquet group vs 737 mL(IQR: 331-1218) in the tourniquet group(P = 0.754). Within the 30-d follow-up period, 9 patients in the tourniquet group and 11 in the non-tourniquet group underwent a reamputation at the trans-femoral level. The use of a tourniquet showed no statistically significant association with the 30-d re-amputation at the femur level in the multiple logistic regression model(P = 0.78). The only variable with a significant association with re-amputation was age(OR = 1.07; P = 0.02).CONCLUSION The results indicate that tourniquets do not cause severe vascular damage with an increased postoperative bleeding or failure rate as the result.展开更多
Introduction Sudden sensorineural hearing loss(SSNHL)is defined as a hearing loss of at least 30 dB over three contiguous frequencies occurring in less than 3 days[1].Vertigo and profound hearing loss are considered p...Introduction Sudden sensorineural hearing loss(SSNHL)is defined as a hearing loss of at least 30 dB over three contiguous frequencies occurring in less than 3 days[1].Vertigo and profound hearing loss are considered poor prognostic factors in SSNHL[2-4].The most common diseases associated with vertigo in SSNHL include BPPV,vestibular neu-[3]展开更多
Title: Analysis of factors influencing true blood loss in navigated total knee replacements. Objectives: To evaluate true blood loss in total knee replacements and analyze the various factors such as gender, BMI, diag...Title: Analysis of factors influencing true blood loss in navigated total knee replacements. Objectives: To evaluate true blood loss in total knee replacements and analyze the various factors such as gender, BMI, diagnosis, size of implants, duration of surgery, tourniquet usage etc. on calculated blood loss using formula by Nadler et al. All the cases included have been done using navigation system and no comparison with conventional jig based surgeries has been attempted. Methods: Retrospectively data of primary cemented total knee replacements performed from October 2012 to August 2013 were evaluated. All surgeries were performed using navigation system. The data collected included patient sex, height, weight and preoperative haemoglobin and hematocrit. The patients’ postoperative data of haemoglobin, hematocrit and drains were collected. All patients had their CBC done on 2nd post operative day. Any data on transfusions that patients received were also collected. We also collected data regarding the size of implant used. We calculated true blood based on formula given by Nadler, Hidalgo & Bloch. We excluded patients whose data were incomplete or who received tranexamic acid. Patients who needed stems (femoral or tibial) were also excluded from this study. Results: The average true calculated blood loss was 959.44 ml. BMI did not have any effect on blood loss. But larger size implants were associated with more blood loss. Conclusion: The preoperative haemoglobin is one of the most important factors in determining transfusion following the knee replacement. Male gender and larger implants are associated with more blood loss. BMI, diagnosis of OA or RA, tourniquet usage and time have no significant effect on blood loss. Our calculated blood loss compares favourably with published literature.展开更多
目的 根据听力损失程度对全聋型突发性聋患者临床再分型,分析全聋型突发性聋患者的临床特征及预后。方法 选取解放军总医院第六医学中心耳鼻咽喉头颈外科医学部耳鼻咽喉内科住院治疗的全聋型突发性聋患者共计928例,依据治疗前患者的纯...目的 根据听力损失程度对全聋型突发性聋患者临床再分型,分析全聋型突发性聋患者的临床特征及预后。方法 选取解放军总医院第六医学中心耳鼻咽喉头颈外科医学部耳鼻咽喉内科住院治疗的全聋型突发性聋患者共计928例,依据治疗前患者的纯音听阈将患者分为1组(80~<95 dB HL)、2组(95~<110 dB HL)和3组(≥110 dB HL),运用非参数秩检验、分层卡方、多因素logistic回归和趋势性检验等方法比较3组全聋型突发性聋患者的临床特征与疗效。结果 (1)临床特征方面:3组全聋型患者的发病到治疗时间(P=0.002)、眩晕发生率(P<0.001)、糖尿病发生率(P=0.012)以及年龄(P=0.014)、发病侧别(P=0.019)均存在差异;而性别(P=0.469)、伴发耳鸣(P=0.099)、耳闷(P=0.098)、高血压(P=0.906)及诱因(P=0.102)无明显差异。(2)听力转归方面:3组全聋型患者在听力治疗的总有效率方面存在差异(P<0.001)。在发病14 d内(P<0.001)和14~40 d(P=0.041)接受治疗的3组全聋型突发性聋患者听力转归存在差异,发病40~180 d(P=0.110)接受治疗的全聋型突发性聋患者的疗效无明显差异。3组全聋型突发性聋患者在低频(P=0.003)、中频(P=0.002)和高频(P=0.013)的听力转归均存在差异。(3)言语识别率方面:言语识别数据完整的294例全聋型突发性聋患者治疗30 d的言语识别率有效率约为36.7%,180 d内的言语识别率有效率约为39.1%。3组患者在治疗后30 d和治疗后180 d的言语识别率疗效存在明显差异(P<0.001)。(4)听力转归影响因素:共计4个因素与患者预后相关,分别为病程(OR=0.95)、年龄(OR=0.99)、听力损失≥110 dB HL(OR=0.67,以80~95 dB HL的患者为参照)和性别(OR=1.40,男性为参照)。结论 不同程度的全聋型突发性聋患者在临床特征、听力转归和言语识别率的治疗有效率方面均存在差异,对全聋型突发性聋患者进行再分型研究有助于提高突发性聋分型诊治的有效率。展开更多
Total loss of talus due to trauma or avascular necrosis,for example,still remains to be a major challenge in foot and ankle surgery with severely limited treatment options.Implantation of a custom made total talar pro...Total loss of talus due to trauma or avascular necrosis,for example,still remains to be a major challenge in foot and ankle surgery with severely limited treatment options.Implantation of a custom made total talar prosthesis has shown promising results so far.Most important factors for long time success are degree of congruence of articular surfaces and ligamentous stability of the ankle.Therefore,our aim was to develop an optimized custom made prosthesis for total talus replacement providing a high level of primary stability.A custom made hemiprosthesis was developed using computed tomography and magnetic resonance imaging data of the affected and contralateral talus considering the principles and technology for the development of the S.T.A.R.prosthesis(Stryker).Additionally,four eyelets for fixation of artificial ligaments were added at the correspondent footprints of the most important ligaments.Two modifications can be provided according to the clinical requirements:A tri-articular hemiprosthesis or a bi-articular hemiprosthesis combined with the tibial component of the S.T.A.R.total ankle replacement system.A feasibility study was performed using a fresh frozen human cadaver.Maximum range of motion of the ankle was measured and ligamentous stability was evaluated by use of standard X-rays after application of varus,valgus or sagittal stress with 150 N.Correct implantation of the prosthesis was technically possible via an anterior approach to the ankle and using standard instruments.Malleolar osteotomies were not required.Maximum ankle dorsiflexion and plantarflexion were measured as 22-0-28 degrees.Maximum anterior displacement of the talus was 6 mm,maximum varus tilt 3 degrees and maximum valgus tilt 2 degrees.Application of an internally braced prosthesis for total talus replacement in humans is technically feasible and might be a reasonable procedure in carefully selected cases with no better alternatives left.展开更多
目的比较驱血带驱血与患肢抬高在全膝关节置换术中的应用效果。方法回顾性收集膝关节骨性关节炎(KOA)行单侧人工全膝关节置换术的90例患者的临床资料。根据患者术中不同的驱血方式,将患者分为驱血带组(50例)和患肢抬高组(40例),比较2组...目的比较驱血带驱血与患肢抬高在全膝关节置换术中的应用效果。方法回顾性收集膝关节骨性关节炎(KOA)行单侧人工全膝关节置换术的90例患者的临床资料。根据患者术中不同的驱血方式,将患者分为驱血带组(50例)和患肢抬高组(40例),比较2组患者围术期失血相关指标、手术前后疼痛视觉模拟评分法(VAS)评分、止血带使用时间、术后输血率、患肢肿胀发生率、下肢深静脉血栓(DVT)及肺栓塞发生情况。结果2组患者失血相关指标、术前VAS评分、术中止血带使用时间、术后输血率及DVT发生率比较差异无统计学意义(P>0.05),但驱血带组患者术后第1 d VAS评分、术后患肢肿胀发生率明显高于患肢抬高组(P<0.05)。结论在全膝关节置换术中,患肢抬高驱血不会增加围术期失血量,而且可以减轻患者术后早期疼痛,减少软组织损伤及患肢肿胀的发生,促进患者快速康复。展开更多
The T-junction model of engine exhaust manifolds significantly influences the simulation precision of the pressure wave and mass flow rate in the intake and exhaust manifolds of diesel engines. Current studies have fo...The T-junction model of engine exhaust manifolds significantly influences the simulation precision of the pressure wave and mass flow rate in the intake and exhaust manifolds of diesel engines. Current studies have focused on constant pressure models, constant static pressure models and pressure loss models. However, low model precision is a common disadvantage when simulating engine exhaust manifolds, particularly for turbocharged systems. To study the performance of junction flow, a cold wind tunnel experiment with high velocities at the junction of a diesel exhaust manifold is performed, and the variation in the pressure loss in the T-junction under different flow conditions is obtained. Despite the trend of the calculated total pressure loss coefficient, which is obtained by using the original pressure loss model and is the same as that obtained from the experimental results, large differences exist between the calculated and experimental values. Furthermore, the deviation becomes larger as the flow velocity increases. By improving the Vazsonyi formula considering the flow velocity and introducing the distribution function, a modified pressure loss model is established, which is suitable for a higher velocity range. Then, the new model is adopted to solve one-dimensional, unsteady flow in a D6114 turbocharged diesel engine. The calculated values are compared with the measured data, and the result shows that the simulation accuracy of the pressure wave before the turbine is improved by 4.3% with the modified pressure loss model because gas compressibility is considered when the flow velocities are high. The research results provide valuable information for further junction flow research, particularly the correction of the boundary condition in one-dimensional simulation models.展开更多
Soil organic carbon(SOC)and total nitrogen(N)concentrations from bulk soils and soil particle size fractions in the different extent of desertified farmlands(potential, light, medium, severe, and most severe desertifi...Soil organic carbon(SOC)and total nitrogen(N)concentrations from bulk soils and soil particle size fractions in the different extent of desertified farmlands(potential, light, medium, severe, and most severe desertified farmlands)were examined to quantitatively elucidate losses of carbon and nitrogen and its mechanisms in the desertification process. Particle size fractions(2 -0.1 mm, 0.1 - 0.05 mm, <0.05 mm)were obtained by granulometric wet sieving from 30 sandy soils(0 - 15cm depth)of different desertified extent. It was shown that soil physical stability index(St)in most severe desertified farmlands was 5 -7% and St in other farmlands was less than 5 %, which contributed to very low soil organic matter content. This was the intrinsic cause that sandy farmlands in Horqin sandy land was subject to risk of desertification. Desertification resulted in considerable losses of SOC and N. Regression analysis indicated that SOC and N content reduced 0.169 g kg-1 and 0.0215 g kg-1 respectively with one percent loss of soil silt and clay content. Losses of SOC and N were mostly the removal of fine particle size fractions(silt and clay, and a less extent very fine sand)from the farmlands by wind erosion, which were rich in organic matter and nutrients, as well as the depletion of organic C and N associated with coarse particles(>0. 05 mm)in desertification process. The concentrations of C and N associated with sand(2 - 0.1 mm and 0.1 - 0.05 mm)significantly decreased with increase of desertified extent. Silt and clay associated C and N concentrations, however, were less changed, and in contrast, were higher in soils under most severe desertified extent than in soils under potential and severe desertified extent. The percentage of distribution in sand(>0.05 mm)associated C and N significantly increased with increase of desertified extent, suggesting that stability of SOC decreased in the desertification process.展开更多
Total knee replacement(TKR) is one of the most common surgeries over the last decade. Patients undergoing TKR are at high risk for postoperative anemia and furthermore for allogeneic blood transfusions(ABT). Complicat...Total knee replacement(TKR) is one of the most common surgeries over the last decade. Patients undergoing TKR are at high risk for postoperative anemia and furthermore for allogeneic blood transfusions(ABT). Complications associated with ABT including chills, rigor, fever, dyspnea, light-headedness should be early recognized in order to lead to a better prognosis. Therefore, perioperative blood management program should be adopted with main aim to reduce the risk of blood transfusion while maximizing hemoglobin simultaneously. Many blood conservation strategies have been attempted including preoperative autologous blood donation, acute normovolemic haemodilution, autologous blood transfusion, intraoperative cell saver, drain clamping, pneumatic tourniquet application, and the use of tranexamic acid. For practical and clinical reasons we will try to classify these strategies in three main stages/pillars: Pre-operative optimization, intra-operative and post-operative protocols. The aim of this work is review the strategies currently in use and reports our experience regarding the perioperative blood management strategies in TKR.展开更多
Taking Zhejiang Province as an example, we use the JOHNES export coefficient model to estimate the total nitrogen (TN) and total phosphorus (TP) load of agricultural planting, livestock and poultry breeding and rural ...Taking Zhejiang Province as an example, we use the JOHNES export coefficient model to estimate the total nitrogen (TN) and total phosphorus (TP) load of agricultural planting, livestock and poultry breeding and rural living non-point source in 2009. Based on the protection cost method in environmental economics, we quantitatively assess the economic loss caused by these three types of non-point source nutrient loss. The results show that in TN non-point source load, the load of land for planting accounts for 57.48%, the load of rural living accounts for 30.22%, and the load of livestock and poultry breeding accounts for 12.30%; in TP non-point source load, the load of rural living accounts for 46.18%, the load of livestock and poultry breeding accounts for 29.00%, and the load of land for planting accounts for 24.82%. The economic loss arising from the agricultural non-point source nutrient loss is equivalent to 2.329 424 7 billion yuan per year (the loss from land for planting accounts for 55.46%; the loss from rural living accounts for 31.21%; the loss from livestock and poultry breeding accounts for 13.33%). It indicates that in order to reduce the loss arising from agricultural non-point source nutrient loss, we should pay attention to controlling the land for planting and rural living source.展开更多
Abstract： The water quality of Dianshan Lake in Shanghai Municipality, China, is impacted by nutrient losses from agricultural lands around the lake. In this study, nine types of agricultural land use were monitored ...Abstract： The water quality of Dianshan Lake in Shanghai Municipality, China, is impacted by nutrient losses from agricultural lands around the lake. In this study, nine types of agricultural land use were monitored in 2010 and 2011, and a correlation analysis between nutrient losses from agricultural non-point sources （NPS） and nutrient stocks in the lake was conducted over monthly and seasonal time periods. The results indicate that the monthly average concentration of total nitrogen （TN） ranged from 1.41 to 7.34 mg/L in 2010 and from 1.52 to 5.90 mg/L in 2011, while the monthly average concentration of total phosphorous （TP） ranged from 0.11 to 0.26 mg/L in 2010 and from 0.13 to 0.30 mg/L in 2011. The annual loss of TN from agricultural NPS was 195.55 tons in 2010 and 208.40 tons in 2011. The cultivation of water oat made the largest contribution to the loss of TN. The annual loss of TP was 44.58 tons in 2010 and 48.12 tons in 2011, and multi-vegetable cultivation made the largest contribution to the loss of TP. The results of correlation analysis show that the monthly stocks of TN and TP in the lake have a positive correlation with the monthly losses of TN and TP from agricultural NPS. According to the seasonal data, the stocks of TN and TP in the lake both have a much stronger correlation with the losses of TN and TP from agricultural NPS in summer than in other seasons. Agricultural NPS pollution control should be the main focus for the water resource conservation in this area.展开更多
为解决现有辨识方法在针对耦合的次/超同步振荡参数提取过程中的噪声适应性差和模态混叠问题,该文提出了一种自适应的变分模态分解法(variational mode decomposition,VMD),定义残差损失总熵、中心频率的切比雪夫距离以及边缘熵共同决...为解决现有辨识方法在针对耦合的次/超同步振荡参数提取过程中的噪声适应性差和模态混叠问题,该文提出了一种自适应的变分模态分解法(variational mode decomposition,VMD),定义残差损失总熵、中心频率的切比雪夫距离以及边缘熵共同决定分解模态数和带宽,结合最小二乘-旋转不变技术(total least square-estimating signal parameter via rotational invariance techniques,TLS-ESPRIT)对分解出的振荡分量进行参数辨识,无需另外使用降噪算法。通过复合信号测试法、PSCAD/EMTDC电磁暂态仿真法验证了所提方法的有效性。最后,将所提方法与改进Prony算法、MCEEMD法在不同噪声水平和振荡频率下进行对比,结果表明,所提方法能够有效地抑制原始信号的噪声干扰,对耦合的次/超同步振荡信号分解更加准确,参数辨识结果可靠性较高,对风电系统振荡溯源、改善系统阻尼具有一定的参考意义。展开更多
目的研究老年患者接受全膝关节置换术(TKA)治疗之后,应用氨甲环酸序贯抗凝+当归补血汤方案进行治疗对康复情况的影响。方法选择研究对象为2021年1月至2022年12月收治的104例拟行TKA治疗的老年膝骨关节炎(KOA)患者,随机两组,每组52例。其...目的研究老年患者接受全膝关节置换术(TKA)治疗之后,应用氨甲环酸序贯抗凝+当归补血汤方案进行治疗对康复情况的影响。方法选择研究对象为2021年1月至2022年12月收治的104例拟行TKA治疗的老年膝骨关节炎(KOA)患者,随机两组,每组52例。其中,观察组给予当归补血汤联合氨甲环酸序贯抗凝治疗,对照组单用氨甲环酸序贯抗凝治疗。比较两组失血相关指标,以及术前和术后1、7、14 d血红蛋白(Hb)、红细胞计数(RBC)、凝血功能指标[凝血酶原时间(PT)、活化部分凝血活酶时间(APTT)、纤维蛋白原(FIB)、D-二聚体(D-D)],以及术前和术后1、3、6个月患膝关节活动度(ROM)和美国特种外科医院(HSS)膝关节评分。统计两组术后并发症情况。结果观察组总失血量、术后引流量、隐性失血量均显著低于对照组(P<0.05),两组术中出血量比较差异无统计学意义(P>0.05)。两组术后1、7 d Hb、RBC均逐渐降低,且均显著低于术前(P<0.05),术后14 d回升,其中观察组升至术前水平(P>0.05);观察组术后1、7、14 d Hb、RBC均显著高于同期对照组(P<0.05)。两组术后1 d PT、APTT均较术前显著缩短(P<0.05),FIB、D-D均较术前显著升高(P<0.05),术后7、14 d均逐渐恢复,至术后14 d均恢复至术前水平(P>0.05);观察组术后1、7 d PT、APTT均显著长于同期对照组(P<0.05),术后1、7 d FIB、D-D均显著低于同期对照组(P<0.05)。两组术后1、3、6个月ROM和HSS评分均逐渐增加,且均显著大于或高于术前(P<0.05);术后1、3、6个月,观察组ROM和HSS评分均显著大于或高于同期对照组(P<0.05)。观察组、对照组并发症发生率分别为9.62%、23.08%,二者差异无统计学意义(P>0.05)。结论对老年TKA患者给予当归补血汤联合氨甲环酸序贯抗凝治疗能有效减少术后隐性失血量,减轻手术对凝血功能的影响,改善术后膝关节功能。展开更多
基金supported by the National Natural Science Foundation of China(No.12301672)the Shanghai Science and Technology Innovation Action Plan(Yangfan Special Project),China(No.23YF1401300)。
文摘The micro-riblet structures have been demonstrated effective in controlling the Total Pressure Loss(TPL)of aero-engine blades.However,due to the considerable scale gap between micro-texture and an actual aero-engine blade,wind tunnel tests and numerical simulations with massive grids directly describing the global flow field are costly for aerodynamic evaluation.Furthermore,the fine micro surface structure brings unavoidable manufacturing errors,and the probability prediction contributes to gaining the confidence interval of the results.Therefore,a novel relay-based probabilistic model for multi-fidelity scenarios in the TPL prediction of a compressor cascade with micro-riblet surfaces is proposed to trade off accuracy and efficiency.Combined with the low-fidelity flow data generated by an aerodynamic solution strategy using the boundary surrogate model and the high-fidelity flow data from the experiment,the relay-based modeling has been achieved through knowledge transferring,and the confidence interval can be provided by the Gaussian Process Regression(GPR)model.The TPL of compressor cascades with micro-riblet surfaces under different surface structures at March number Ma=0.64,0.74,0.84 have been evaluated using the Relay-Based Probabilistic(RBP)model.The results illustrate that the RBP model could provide higher accuracy than the Single-Fidelity-Data-Driven(SFDD)prediction model,which show the promising potential of multi-fidelity scenarios data fusion in the aerodynamic evaluation of multi-scale configurations.
基金supported in part by MBIE New Zealand through the Advanced Energy Technology Platform program‘High Power Electric Motors for Large-Scale Transport’(contract RTVU2004)by the Air Force Office of Scientific Research(award FA2386-22-1-4054)+1 种基金by the Royal Society Marsden Fund of New Zealand Vice-Chancellors’Committee(grant MFP-VUW2205)‘Underpinning High-Temperature Superconducting Nuclear Fusion Reactor Technology’.
文摘No-insulation(NI)coils emerged as a viable alternative to traditional insulated(INS)high temperature super-conducting(HTS)coils primarily due to their inherent ability to self-protect during quench and enhanced me-chanical stability.When coils carrying direct current(DC)are exposed to an external alternating current(AC)magnetic field,total loss in the coil is the sum of magnetisation loss due to the AC field and dynamic loss arising from the interaction between the DC current and the AC field.In this work,we numerically study the total loss and its components in NI and INS double-pancake coils(DPCs)of identical dimensions,wound with 4 mm wide SuperPower Rare-earth barium copper oxide(ReBCO)coated conductor(CC)tapes at 77 K.The analysis is carried out for external AC magnetic fields up to 200 mT at 72.73 Hz,with the coil carrying DC current up to 90%of the coil self-field critical current.The results show that under a perpendicular magnetic field,the total loss and its components in the INS-DPC are higher than in the NI-DPC,which is attributed to the presence of insu-lation which hinders the current bypass.The NI-DPC and INS-DPC coils show similar electromagnetic behaviour under the perpendicular field,and the evolution of dynamic resistance,which gives rise to dynamic loss,is also similar.Under parallel field the loss in the NI-DPC is higher than that for the perpendicular field,and the coil level shielding similar to bulk superconductor is also observed.Surprisingly,under parallel fields,a dynamic resistance higher than that under perpendicular fields is evident in the NI-DPC,arising from a finite average electric field over a cycle.
基金NZ Royal Society Marsden under Grant MFP-VUW2205New Zealand Ministry of Business,Innovation and Employment under the Advanced Energy Technology Platform program“High power electric motors for large scale transport”under Grant RTVU2004.
文摘REBCO tapes carry DC current under AC magnetic fields in proposed HTS fusion applications. AC loss will be generated in the process and it is important to understand the AC loss behaviour for safe operation of the fusion magnets. In this work, magnetisation loss (Qm), dynamic resistance (Rdyn), and total loss (Qtotal) in four different REBCO tapes are numerically studied, using the measured and , for the magnetic field amplitude applied perpendicularly up to 8 T at 20 K and 50 K, where represents the magnetic field and field angle () dependent critical current density. The peak of Theva data is different from that of other tapes. We artificially shifted the ab-plane peak of Theva to the left by 25° to match the peak value. The newly shifted data is named as Theva-shift, which was also investigated to study the influence of the Theva peak shift on AC loss. The normalised DC transport current level (i = It/Ic0) ranges from 0.05 to 0.9, where the DC current amplitude and the self-critical current of the tape are represented by It and Ic0, respectively. The simulation results show that the AC losses deviate significantly from the Brandt-Indenbom (BI) equation at high magnetic fields. Jc and instantaneous loss curves for different tapes show correlation at high magnetic fields. The simulation results also show how different characteristics for different tapes influence AC losses. When AC loss values are scaled by the self-field critical current, Qm without current and Qtotal with current in the different tapes show a good agreement. It implies that the temperature dependence of the two types of loss can be calculated from a known loss at one temperature and the self-field critical current.
文摘AIM To investigate the total blood loss(TBL) and the safety with respect to the re-amputation rate after transtibial amputation(TTA) conducted with and without a tourniquet. METHODS The study was a single-centre retrospective cohort study of patients with a primary TTA admitted between January 2013 and April 2015. All patients with a primary TTA were assessed for inclusion if the amputation was performed because of arteriosclerosis or diabetic complications. All patients underwent a standardized TTA procedure that was performed approximately 10 cm below the knee joint and performed with sagittalflaps. The pneumatic tourniquet, when used, was inflated around the femur to a pressure of 100 mmH g above the systolic blood pressure. The number of blood transfusions within the first four postoperative days was recorded. The intraoperative blood loss(OBL), which is defined as the volume of blood lost during surgery, was determined from the suction volume and by the weight difference of the surgical dressings. The trigger for a blood transfusion was set at a decrease in the Hgb level < 9.67 g/dL(6 mmol/L). Transfusions were performed with pooled red blood cells containing 245 m L per portion, which equals 55 g/L of haemoglobin. The TBL during the first four postoperative days was calculated based on the haemoglobin level and the estimated blood volume. The re-amputation rate was evaluated within 30 d. RESULTS Seventy-four out of 86 consecutive patients who underwent TTA within the two-year study period were included in the analysis. Of these, 38 were operated on using a tourniquet and 36 were operated on without using a tourniquet. There were no significant preoperative differences between the groups. The patients in both groups had a postoperative decrease in their Hgb level compared with preoperative baseline values. The patients operated on using a tourniquet received approximately three millilitres less blood transfusion per kilogram body weight compared with patients operated on without a tourniquet. The duration of surgery was shorter and the OBL was less for the tourniquet group than the non-tourniquet group, whereas no significant difference was observed for the TBL. The TBL median was 859 mL(IQR: 383-1315) in the non-tourniquet group vs 737 mL(IQR: 331-1218) in the tourniquet group(P = 0.754). Within the 30-d follow-up period, 9 patients in the tourniquet group and 11 in the non-tourniquet group underwent a reamputation at the trans-femoral level. The use of a tourniquet showed no statistically significant association with the 30-d re-amputation at the femur level in the multiple logistic regression model(P = 0.78). The only variable with a significant association with re-amputation was age(OR = 1.07; P = 0.02).CONCLUSION The results indicate that tourniquets do not cause severe vascular damage with an increased postoperative bleeding or failure rate as the result.
文摘Introduction Sudden sensorineural hearing loss(SSNHL)is defined as a hearing loss of at least 30 dB over three contiguous frequencies occurring in less than 3 days[1].Vertigo and profound hearing loss are considered poor prognostic factors in SSNHL[2-4].The most common diseases associated with vertigo in SSNHL include BPPV,vestibular neu-[3]
文摘Title: Analysis of factors influencing true blood loss in navigated total knee replacements. Objectives: To evaluate true blood loss in total knee replacements and analyze the various factors such as gender, BMI, diagnosis, size of implants, duration of surgery, tourniquet usage etc. on calculated blood loss using formula by Nadler et al. All the cases included have been done using navigation system and no comparison with conventional jig based surgeries has been attempted. Methods: Retrospectively data of primary cemented total knee replacements performed from October 2012 to August 2013 were evaluated. All surgeries were performed using navigation system. The data collected included patient sex, height, weight and preoperative haemoglobin and hematocrit. The patients’ postoperative data of haemoglobin, hematocrit and drains were collected. All patients had their CBC done on 2nd post operative day. Any data on transfusions that patients received were also collected. We also collected data regarding the size of implant used. We calculated true blood based on formula given by Nadler, Hidalgo & Bloch. We excluded patients whose data were incomplete or who received tranexamic acid. Patients who needed stems (femoral or tibial) were also excluded from this study. Results: The average true calculated blood loss was 959.44 ml. BMI did not have any effect on blood loss. But larger size implants were associated with more blood loss. Conclusion: The preoperative haemoglobin is one of the most important factors in determining transfusion following the knee replacement. Male gender and larger implants are associated with more blood loss. BMI, diagnosis of OA or RA, tourniquet usage and time have no significant effect on blood loss. Our calculated blood loss compares favourably with published literature.
文摘目的 根据听力损失程度对全聋型突发性聋患者临床再分型,分析全聋型突发性聋患者的临床特征及预后。方法 选取解放军总医院第六医学中心耳鼻咽喉头颈外科医学部耳鼻咽喉内科住院治疗的全聋型突发性聋患者共计928例,依据治疗前患者的纯音听阈将患者分为1组(80~<95 dB HL)、2组(95~<110 dB HL)和3组(≥110 dB HL),运用非参数秩检验、分层卡方、多因素logistic回归和趋势性检验等方法比较3组全聋型突发性聋患者的临床特征与疗效。结果 (1)临床特征方面:3组全聋型患者的发病到治疗时间(P=0.002)、眩晕发生率(P<0.001)、糖尿病发生率(P=0.012)以及年龄(P=0.014)、发病侧别(P=0.019)均存在差异;而性别(P=0.469)、伴发耳鸣(P=0.099)、耳闷(P=0.098)、高血压(P=0.906)及诱因(P=0.102)无明显差异。(2)听力转归方面:3组全聋型患者在听力治疗的总有效率方面存在差异(P<0.001)。在发病14 d内(P<0.001)和14~40 d(P=0.041)接受治疗的3组全聋型突发性聋患者听力转归存在差异,发病40~180 d(P=0.110)接受治疗的全聋型突发性聋患者的疗效无明显差异。3组全聋型突发性聋患者在低频(P=0.003)、中频(P=0.002)和高频(P=0.013)的听力转归均存在差异。(3)言语识别率方面:言语识别数据完整的294例全聋型突发性聋患者治疗30 d的言语识别率有效率约为36.7%,180 d内的言语识别率有效率约为39.1%。3组患者在治疗后30 d和治疗后180 d的言语识别率疗效存在明显差异(P<0.001)。(4)听力转归影响因素:共计4个因素与患者预后相关,分别为病程(OR=0.95)、年龄(OR=0.99)、听力损失≥110 dB HL(OR=0.67,以80~95 dB HL的患者为参照)和性别(OR=1.40,男性为参照)。结论 不同程度的全聋型突发性聋患者在临床特征、听力转归和言语识别率的治疗有效率方面均存在差异,对全聋型突发性聋患者进行再分型研究有助于提高突发性聋分型诊治的有效率。
文摘Total loss of talus due to trauma or avascular necrosis,for example,still remains to be a major challenge in foot and ankle surgery with severely limited treatment options.Implantation of a custom made total talar prosthesis has shown promising results so far.Most important factors for long time success are degree of congruence of articular surfaces and ligamentous stability of the ankle.Therefore,our aim was to develop an optimized custom made prosthesis for total talus replacement providing a high level of primary stability.A custom made hemiprosthesis was developed using computed tomography and magnetic resonance imaging data of the affected and contralateral talus considering the principles and technology for the development of the S.T.A.R.prosthesis(Stryker).Additionally,four eyelets for fixation of artificial ligaments were added at the correspondent footprints of the most important ligaments.Two modifications can be provided according to the clinical requirements:A tri-articular hemiprosthesis or a bi-articular hemiprosthesis combined with the tibial component of the S.T.A.R.total ankle replacement system.A feasibility study was performed using a fresh frozen human cadaver.Maximum range of motion of the ankle was measured and ligamentous stability was evaluated by use of standard X-rays after application of varus,valgus or sagittal stress with 150 N.Correct implantation of the prosthesis was technically possible via an anterior approach to the ankle and using standard instruments.Malleolar osteotomies were not required.Maximum ankle dorsiflexion and plantarflexion were measured as 22-0-28 degrees.Maximum anterior displacement of the talus was 6 mm,maximum varus tilt 3 degrees and maximum valgus tilt 2 degrees.Application of an internally braced prosthesis for total talus replacement in humans is technically feasible and might be a reasonable procedure in carefully selected cases with no better alternatives left.
文摘目的比较驱血带驱血与患肢抬高在全膝关节置换术中的应用效果。方法回顾性收集膝关节骨性关节炎(KOA)行单侧人工全膝关节置换术的90例患者的临床资料。根据患者术中不同的驱血方式,将患者分为驱血带组(50例)和患肢抬高组(40例),比较2组患者围术期失血相关指标、手术前后疼痛视觉模拟评分法(VAS)评分、止血带使用时间、术后输血率、患肢肿胀发生率、下肢深静脉血栓(DVT)及肺栓塞发生情况。结果2组患者失血相关指标、术前VAS评分、术中止血带使用时间、术后输血率及DVT发生率比较差异无统计学意义(P>0.05),但驱血带组患者术后第1 d VAS评分、术后患肢肿胀发生率明显高于患肢抬高组(P<0.05)。结论在全膝关节置换术中,患肢抬高驱血不会增加围术期失血量,而且可以减轻患者术后早期疼痛,减少软组织损伤及患肢肿胀的发生,促进患者快速康复。
文摘The T-junction model of engine exhaust manifolds significantly influences the simulation precision of the pressure wave and mass flow rate in the intake and exhaust manifolds of diesel engines. Current studies have focused on constant pressure models, constant static pressure models and pressure loss models. However, low model precision is a common disadvantage when simulating engine exhaust manifolds, particularly for turbocharged systems. To study the performance of junction flow, a cold wind tunnel experiment with high velocities at the junction of a diesel exhaust manifold is performed, and the variation in the pressure loss in the T-junction under different flow conditions is obtained. Despite the trend of the calculated total pressure loss coefficient, which is obtained by using the original pressure loss model and is the same as that obtained from the experimental results, large differences exist between the calculated and experimental values. Furthermore, the deviation becomes larger as the flow velocity increases. By improving the Vazsonyi formula considering the flow velocity and introducing the distribution function, a modified pressure loss model is established, which is suitable for a higher velocity range. Then, the new model is adopted to solve one-dimensional, unsteady flow in a D6114 turbocharged diesel engine. The calculated values are compared with the measured data, and the result shows that the simulation accuracy of the pressure wave before the turbine is improved by 4.3% with the modified pressure loss model because gas compressibility is considered when the flow velocities are high. The research results provide valuable information for further junction flow research, particularly the correction of the boundary condition in one-dimensional simulation models.
文摘Soil organic carbon(SOC)and total nitrogen(N)concentrations from bulk soils and soil particle size fractions in the different extent of desertified farmlands(potential, light, medium, severe, and most severe desertified farmlands)were examined to quantitatively elucidate losses of carbon and nitrogen and its mechanisms in the desertification process. Particle size fractions(2 -0.1 mm, 0.1 - 0.05 mm, <0.05 mm)were obtained by granulometric wet sieving from 30 sandy soils(0 - 15cm depth)of different desertified extent. It was shown that soil physical stability index(St)in most severe desertified farmlands was 5 -7% and St in other farmlands was less than 5 %, which contributed to very low soil organic matter content. This was the intrinsic cause that sandy farmlands in Horqin sandy land was subject to risk of desertification. Desertification resulted in considerable losses of SOC and N. Regression analysis indicated that SOC and N content reduced 0.169 g kg-1 and 0.0215 g kg-1 respectively with one percent loss of soil silt and clay content. Losses of SOC and N were mostly the removal of fine particle size fractions(silt and clay, and a less extent very fine sand)from the farmlands by wind erosion, which were rich in organic matter and nutrients, as well as the depletion of organic C and N associated with coarse particles(>0. 05 mm)in desertification process. The concentrations of C and N associated with sand(2 - 0.1 mm and 0.1 - 0.05 mm)significantly decreased with increase of desertified extent. Silt and clay associated C and N concentrations, however, were less changed, and in contrast, were higher in soils under most severe desertified extent than in soils under potential and severe desertified extent. The percentage of distribution in sand(>0.05 mm)associated C and N significantly increased with increase of desertified extent, suggesting that stability of SOC decreased in the desertification process.
文摘Total knee replacement(TKR) is one of the most common surgeries over the last decade. Patients undergoing TKR are at high risk for postoperative anemia and furthermore for allogeneic blood transfusions(ABT). Complications associated with ABT including chills, rigor, fever, dyspnea, light-headedness should be early recognized in order to lead to a better prognosis. Therefore, perioperative blood management program should be adopted with main aim to reduce the risk of blood transfusion while maximizing hemoglobin simultaneously. Many blood conservation strategies have been attempted including preoperative autologous blood donation, acute normovolemic haemodilution, autologous blood transfusion, intraoperative cell saver, drain clamping, pneumatic tourniquet application, and the use of tranexamic acid. For practical and clinical reasons we will try to classify these strategies in three main stages/pillars: Pre-operative optimization, intra-operative and post-operative protocols. The aim of this work is review the strategies currently in use and reports our experience regarding the perioperative blood management strategies in TKR.
基金Supported by 211 Double Support Plan Project of Sichuan Agricultural University (2009-3-27)
文摘Taking Zhejiang Province as an example, we use the JOHNES export coefficient model to estimate the total nitrogen (TN) and total phosphorus (TP) load of agricultural planting, livestock and poultry breeding and rural living non-point source in 2009. Based on the protection cost method in environmental economics, we quantitatively assess the economic loss caused by these three types of non-point source nutrient loss. The results show that in TN non-point source load, the load of land for planting accounts for 57.48%, the load of rural living accounts for 30.22%, and the load of livestock and poultry breeding accounts for 12.30%; in TP non-point source load, the load of rural living accounts for 46.18%, the load of livestock and poultry breeding accounts for 29.00%, and the load of land for planting accounts for 24.82%. The economic loss arising from the agricultural non-point source nutrient loss is equivalent to 2.329 424 7 billion yuan per year (the loss from land for planting accounts for 55.46%; the loss from rural living accounts for 31.21%; the loss from livestock and poultry breeding accounts for 13.33%). It indicates that in order to reduce the loss arising from agricultural non-point source nutrient loss, we should pay attention to controlling the land for planting and rural living source.
基金supported by the Project of the Shanghai Science and Technology Committee(Grants No.08DZ1203200 and 08DZ1203205)
文摘Abstract： The water quality of Dianshan Lake in Shanghai Municipality, China, is impacted by nutrient losses from agricultural lands around the lake. In this study, nine types of agricultural land use were monitored in 2010 and 2011, and a correlation analysis between nutrient losses from agricultural non-point sources （NPS） and nutrient stocks in the lake was conducted over monthly and seasonal time periods. The results indicate that the monthly average concentration of total nitrogen （TN） ranged from 1.41 to 7.34 mg/L in 2010 and from 1.52 to 5.90 mg/L in 2011, while the monthly average concentration of total phosphorous （TP） ranged from 0.11 to 0.26 mg/L in 2010 and from 0.13 to 0.30 mg/L in 2011. The annual loss of TN from agricultural NPS was 195.55 tons in 2010 and 208.40 tons in 2011. The cultivation of water oat made the largest contribution to the loss of TN. The annual loss of TP was 44.58 tons in 2010 and 48.12 tons in 2011, and multi-vegetable cultivation made the largest contribution to the loss of TP. The results of correlation analysis show that the monthly stocks of TN and TP in the lake have a positive correlation with the monthly losses of TN and TP from agricultural NPS. According to the seasonal data, the stocks of TN and TP in the lake both have a much stronger correlation with the losses of TN and TP from agricultural NPS in summer than in other seasons. Agricultural NPS pollution control should be the main focus for the water resource conservation in this area.
文摘为解决现有辨识方法在针对耦合的次/超同步振荡参数提取过程中的噪声适应性差和模态混叠问题,该文提出了一种自适应的变分模态分解法(variational mode decomposition,VMD),定义残差损失总熵、中心频率的切比雪夫距离以及边缘熵共同决定分解模态数和带宽,结合最小二乘-旋转不变技术(total least square-estimating signal parameter via rotational invariance techniques,TLS-ESPRIT)对分解出的振荡分量进行参数辨识,无需另外使用降噪算法。通过复合信号测试法、PSCAD/EMTDC电磁暂态仿真法验证了所提方法的有效性。最后,将所提方法与改进Prony算法、MCEEMD法在不同噪声水平和振荡频率下进行对比,结果表明,所提方法能够有效地抑制原始信号的噪声干扰,对耦合的次/超同步振荡信号分解更加准确,参数辨识结果可靠性较高,对风电系统振荡溯源、改善系统阻尼具有一定的参考意义。
文摘目的研究老年患者接受全膝关节置换术(TKA)治疗之后,应用氨甲环酸序贯抗凝+当归补血汤方案进行治疗对康复情况的影响。方法选择研究对象为2021年1月至2022年12月收治的104例拟行TKA治疗的老年膝骨关节炎(KOA)患者,随机两组,每组52例。其中,观察组给予当归补血汤联合氨甲环酸序贯抗凝治疗,对照组单用氨甲环酸序贯抗凝治疗。比较两组失血相关指标,以及术前和术后1、7、14 d血红蛋白(Hb)、红细胞计数(RBC)、凝血功能指标[凝血酶原时间(PT)、活化部分凝血活酶时间(APTT)、纤维蛋白原(FIB)、D-二聚体(D-D)],以及术前和术后1、3、6个月患膝关节活动度(ROM)和美国特种外科医院(HSS)膝关节评分。统计两组术后并发症情况。结果观察组总失血量、术后引流量、隐性失血量均显著低于对照组(P<0.05),两组术中出血量比较差异无统计学意义(P>0.05)。两组术后1、7 d Hb、RBC均逐渐降低,且均显著低于术前(P<0.05),术后14 d回升,其中观察组升至术前水平(P>0.05);观察组术后1、7、14 d Hb、RBC均显著高于同期对照组(P<0.05)。两组术后1 d PT、APTT均较术前显著缩短(P<0.05),FIB、D-D均较术前显著升高(P<0.05),术后7、14 d均逐渐恢复,至术后14 d均恢复至术前水平(P>0.05);观察组术后1、7 d PT、APTT均显著长于同期对照组(P<0.05),术后1、7 d FIB、D-D均显著低于同期对照组(P<0.05)。两组术后1、3、6个月ROM和HSS评分均逐渐增加,且均显著大于或高于术前(P<0.05);术后1、3、6个月,观察组ROM和HSS评分均显著大于或高于同期对照组(P<0.05)。观察组、对照组并发症发生率分别为9.62%、23.08%,二者差异无统计学意义(P>0.05)。结论对老年TKA患者给予当归补血汤联合氨甲环酸序贯抗凝治疗能有效减少术后隐性失血量,减轻手术对凝血功能的影响,改善术后膝关节功能。
