The present research of cold-beating formation mainly focused on roller design and manufacture, kinematics, constitutive relation, metal flow law, thermo-mechanical coupling, surface micro-topography and microstructur...The present research of cold-beating formation mainly focused on roller design and manufacture, kinematics, constitutive relation, metal flow law, thermo-mechanical coupling, surface micro-topography and microstructure evolution. However, the research on surface quality and performance of workpieces in the process of cold-beating is rare. Cold-beating simulation experiment of 1020 steel is conducted at room temperature and strain rates ranging from 2000 to 4000 s^-1 base on the law of plastic forming. According to the experimental data, the model of strain hardening of 1020 steel is established, Scanning Electron Microscopy（SEM） is conducted, the mechanism of the work hardening of 1020 steel is clarified by analyzing microstructure variation of 1020 steel. It is found that the strain rate hardening effect of 1020 steel is stronger than the softening effect induced by increasing temperatures, the process of simulation cold-beating cause the grain shape of 1020 steel significant change and microstructure elongate significantly to form a fibrous tis- sue parallel to the direction of deformation, the higher strain rate, the more obvious grain refinement and the more hardening effect. Additionally, the change law of the work hardening rate is investigated, the relationship between dislocation density and strain, the relationship between work hardening rate and dislocation density is obtained. Results show that the change trend of the work hardening rate of 1020 steel is divided into two stages, the work hardening rate decreases dramatically in the first stage and slowly decreases in the second stage, finally tending toward zero. Dislocation density increases with increasing strain and strain rate, work hardening rate decreases with increasing dislocation density. The research results provide the basis for solving the problem of improving the surface quality and performance of workpieces under cold-beating formation of 1020 steel.展开更多
The present research on involute spline cold roll-beating forming is mainly about the principles and motion relations of cold roll-beating,the theory of roller design,and the stress and strain field analysis of cold r...The present research on involute spline cold roll-beating forming is mainly about the principles and motion relations of cold roll-beating,the theory of roller design,and the stress and strain field analysis of cold roll-beating,etc.However,the research on law of metal flow in the forming process of involute spline cold roll-beating is rare.According to the principle of involute spline cold roll-beating,the contact model between the rollers and the spline shaft blank in the process of cold roll-beating forming is established,and the theoretical analysis of metal flow in the cold roll-beating deforming region is proceeded.A finite element model of the spline cold roll-beating process is established,the formation mechanism of the involute spline tooth profile in cold roll-beating forming process is studied,and the node flow tracks of the deformation area are analyzed.The experimental research on the metal flow of cold roll-beating spline is conducted,and the metallographic structure variation,grain characteristics and metal flow line of the different tooth profile area are analyzed.The experimental results show that the particle flow directions of the deformable bodies in cold roll-beating deformation area are determined by the minimum moving resistance.There are five types of metal flow rules of the deforming region in the process of cold roll-beating forming.The characteristics of involute spline cold roll-beating forming are given,and the forming mechanism of involute spline cold roll-beating is revealed.This paper researches the law of metal flow in the forming process of involute spline cold roll-beating,which provides theoretical supports for solving the tooth profile forming quality problem.展开更多
针对锅炉过热汽温系统存在的大时延、强非线性和变量耦合等建模难题,建立了一种基于贝叶斯优化时间序列预测神经基扩展分析(neural basis expansion analysis for interpretable time series forecasting,N-BEATS)网络的过热汽温预测模...针对锅炉过热汽温系统存在的大时延、强非线性和变量耦合等建模难题,建立了一种基于贝叶斯优化时间序列预测神经基扩展分析(neural basis expansion analysis for interpretable time series forecasting,N-BEATS)网络的过热汽温预测模型。针对某600 MW超临界火电机组,结合机理分析确定模型的输入和输出变量,通过性能对比实验优化模型的输入/输出时延阶次、Block类型和激活函数,进一步利用贝叶斯优化算法对模型的超参数进行寻优,并与网格搜索、遗传算法的优化效果进行对比。采用该机组仿真运行数据进行建模实验,结果表明所提模型在预测精度方面优于传统优化方法及主流模型。展开更多
Ramsey oscillations typically exhibit an exponential decay envelope due to environmental noise. However,recent experiments have observed nonmonotonic Ramsey fringes characterized by beating patterns, which deviate fro...Ramsey oscillations typically exhibit an exponential decay envelope due to environmental noise. However,recent experiments have observed nonmonotonic Ramsey fringes characterized by beating patterns, which deviate from the standard behavior. These beating patterns have primarily been attributed to charge-noise fluctuations.In this paper, we have experimentally observed Ramsey fringe with beating pattern for transmon qubits, and traced the origin to electric instruments induced flux noise.展开更多
The evolution of the S'precipitate in Al−Cu−Mg alloy was investigated using transmission electron microscopy(TEM),high-angle annular dark-field scanning transmission electron microscopy(HAADF−STEM),molecular dynam...The evolution of the S'precipitate in Al−Cu−Mg alloy was investigated using transmission electron microscopy(TEM),high-angle annular dark-field scanning transmission electron microscopy(HAADF−STEM),molecular dynamics(MD)simulations,and other analytical techniques.The precipitation behavior during different aging stages of the supersaturated solid solution formed after rapid cold punching was focused,which induces rapid dissolution of precipitates.The findings reveal that the precipitation sequence is significantly influenced by aging temperature.At higher aging temperatures,which mitigate lattice distortion in the matrix,the precipitation sequence follows the conventional path.Conversely,at lower aging temperatures,where lattice distortion persists,the sequence deviates,suppressing the formation of Guinier−Preston−Bagaryatsky(GPB)zones.MD simulations confirm that the variations in solute atom diffusion rates at different aging temperatures lead to the differences in the S'phase precipitation sequence.展开更多
BACKGROUND: Although the use of non-heart beating donors (NHBDs) could bridge the widening gap between organ demand and supply, its application to liver transplantation is limited due to the high incidence of primary ...BACKGROUND: Although the use of non-heart beating donors (NHBDs) could bridge the widening gap between organ demand and supply, its application to liver transplantation is limited due to the high incidence of primary graft loss. Prevention of liver injury in NHBDs will benefit the results of transplantation. This study was conducted to evaluate the protective effects of L-arginine on liver grafts from NHBDs. METHODS: One hundred and four Wistar rats were randomly divided into 7 groups: normal control (n=8) controls 1, 2 and 3 (C-1, C-2, C-3, n=16), and experimental 1, 2 and 3 (E-1, E-2, E-3, n=16). For groups C-1 and E-1, C-2 and E-2, and C-3 and E-3, the warm ischemia time was 0, 30, and 45 minutes, respectively. Liver grafts were flushed with and preserved in 4 degrees C Euro-collins solution containing 1 mmol/L L-arginine for 1 hour in each experimental group. Recipients of each experimental group were injected with L-arginine (10 mg/kg body weight) by tail vein 10 minutes before portal vein reperfusion. Donors and recipients of each experimental control group were treated with normal saline. Then transplantation was performed. At 1, 3, and 24 hours after portal vein reperfusion, blood samples were obtained to determine the levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), nitric oxide (NO) and plasma endothelin (ET). At 3 hours after portal vein reperfusion, grafts samples were fixed in 2.5% glutaraldehyde for electron microscopic observation. RESULTS: At I hour after portal vein reperfusion, the levels of NO in groups E-1, E-2, E-3 and C-1, C-2, C-3 were lower, while the levels of plasma ET, serum ALT and AST were higher than those in the normal control group (P<0.05). At 1, 3, and 24 hours, the levels of NO in groups E-1, E-2, E-3 were higher, while the levels of plasma ET, serum ALT and AST were lower than those in the corresponding control groups (C-1, C-2, C-3) (P<0.05). The levels of NO in groups C-2 and C-3 were lower than in group C-1 (P<0.05), and the level of NO in group C-3 was lower than in group C-2 (P<0.05). At 1, 3 and 24 hours, the levels of plasma ET, serum ALT, and AST in groups E-1, E-2, E-3 were lower than those in the corresponding control groups (C-1, C-2, C-3) (P<0.05). The levels of plasma ET, serum ALT, and AST were lower in group C-3 than in groups C-1 and C-2 (P<0.05). Pathological changes in groups E-1, E-2, E-3 were milder than those in the corresponding experimental control groups (C-1, C-2, C-3). CONCLUSIONS: The imbalance between NO and ET plays an important role in the development of ischemia-reperfusion injury of liver grafts from NHBDs. L-arginine can attenuate injury in liver grafts from NHBDs by improving the balance between NO and ET.展开更多
In this paper,what causes the setting-on place of woven fabrics without adopting tension compensation is explained by means of experimental methods.Owing to that the main shaft speed and the beating speed of reed can ...In this paper,what causes the setting-on place of woven fabrics without adopting tension compensation is explained by means of experimental methods.Owing to that the main shaft speed and the beating speed of reed can not attain the normal values at setting-on,the warp tension and the beating force of the reed can neither reach the normal level.Therefore,the relative slippage movement of the weft against the warp during beating will be less,while the common movement of the weft together with the warp will be bigger than those at nor-mal running.As a result,the setting-on place is展开更多
Diagnostic techniques of CEOF, power spectrum and bandpass filter wave are applied in this paper to analyze the seasonal northward beating of the northern subtropical high using day to day geopotential fields of 2.5 &...Diagnostic techniques of CEOF, power spectrum and bandpass filter wave are applied in this paper to analyze the seasonal northward beating of the northern subtropical high using day to day geopotential fields of 2.5 ×2.5 at 500 hPa May through July in 1988 and 1991. It is concluded that it is globally observed that the subtropical high has northward beats that propagate westward; the source of beating mainly lies in the region of Arabian Sea and central Pacific and the sink in eastern Pacific; the seasonal beating is dominated by effects of the disturbance field; low frequency oscillation plays a key role in the beating and the westward propagation so that the difference in the latter in individual years is caused by the varying source of disturbance and the low frequency waves it excites.展开更多
In this paper, the intrinsic behavior of rotating Euler Benoulli flexible shafts was studied due to coupled bending and torsional vibrations. The equations of motion of the shaft with unbalanced eccentricity and visc...In this paper, the intrinsic behavior of rotating Euler Benoulli flexible shafts was studied due to coupled bending and torsional vibrations. The equations of motion of the shaft with unbalanced eccentricity and viscous material damping were derived by the Hamilton principle. The numerical solution was obtained using the perturbation approach and mode assuming method. The influences of the coupled vibrations between the bending and torsion, the rotating speed, material damping and the slenderness ratio of the shaft were analyzed. It is clearly shown that the beating phenomena can occur when the interaction of torsion and flexure is considered.展开更多
Objective: To study the outcome of normothermic beating heart pulmonary thromboendarterectomy (PTE) performed in patients with chronic pulmonary thromboembolism. Methodology: A retrospective analysis of 15 patients wh...Objective: To study the outcome of normothermic beating heart pulmonary thromboendarterectomy (PTE) performed in patients with chronic pulmonary thromboembolism. Methodology: A retrospective analysis of 15 patients who underwent PTE under normothermic beating heart cardio-pulmonary bypass from July 2009 to September 2018 was done. The patients were followed up with clinical assessment, transthoracic echocardiography and computerized tomographicangiography (CTA) for 1 month to 82 months. Results: Data were analysed for 15 consecutive patients. Mean age of the patients was 35.28 years and 10 patients were male. Pre-operatively 6 (40%) patients presented with New York Heart Association (NYHA) class II dyspnoea on exertion symptomatology, 7 (47%) were in NHYA class III, and 2 (13%) were in NYHA class IV. The preoperative and postoperative mean pulmonary artery pressures (mPAP) (mmHg) were 36.50 ± 11.3 and 20.21 ± 7.19, the systolic PAPs (mmHg) were 73.35 ± 14.12 and 35.21 ± 7.89 and the diastolic PAPs (mmHg) were 19.28 ± 8.60 and 12.85 ± 7.26 respectively. 2 (13%) patients had Jamieson’s type I and 12 (87%) had Jamieson type II disease. One patient (7%) expired on 9th postoperative day. All the patients had improved pulmonary gas exchange and did not require oxygen supplementation from 5th postoperative day;symptoms improved to NYHA class I & II in 12 (80%) & 3 (20%) of patients respectively. There was no reperfusion pulmonary edema or any neurologic complications. Postoperative echocardiogram showed improved right ventricular function and Computerised Tomographic Angiogram showed completeness of the procedure. Conclusion: Pulmonary thromboendarterectomy under normothermic beating heart cardiopulmonary bypass has good immediate postoperative results with significant progressive improvement in hemodynamics and quality of life during the course of follow-up. The results were not only comparable to those of the procedure done under deep hypothermic circulatory arrest by other centres but also without its associated adverse events. This technique requires more expertise but gives equivalent good results in immediate and short- to mid-term follow-up with less morbidity than the standard procedure, but it requires long-term follow-up to substantiate the evidence.展开更多
We experimentally study the controllable generation of a beating signal using stored light pulses based on electromagnetically induced transparency(EIT) in a solid medium. The beating signal relies on an asymmetric pr...We experimentally study the controllable generation of a beating signal using stored light pulses based on electromagnetically induced transparency(EIT) in a solid medium. The beating signal relies on an asymmetric procedure of light storage and retrieval. After storing the probe pulse into the spin coherence under the EIT condition, two-color control fields with opposite detunings instead of the initial control field are used to scatter the stored spin coherence. The controllable beating signal is generated due to alternative constructive and destructive interferences in the retrieved signal intensities. The beating of the two-color control fields is mapped into the beating of weak probe fields by using atomic spin coherence. This beating signal will be important in precise atomic spectroscopy and fast quantum limited measurements.展开更多
The most important performance of a beating-up mechanism is that the dwelling time of the sley must ensure the completion of the weft insertion. To meet this requirement, a new non-circular combined gear train beating...The most important performance of a beating-up mechanism is that the dwelling time of the sley must ensure the completion of the weft insertion. To meet this requirement, a new non-circular combined gear train beating-up mechanism which is composed of two-stage planetary gear trains is proposed. The first-stage is a Fourier planetary gear train and the second-stage is a non-circular planetary gear train. For designing of this new mechanism, the ideal kinematic equations of the sley are constructed first. Then the kinematic model of the first-stage Fourier planetary gear train is established and the reverse solution for the pitch curves of the second-stage non-circular gears is deduced. With a computer-aided design program, the influences of several important parameters on the pitch curves of the second-stage non-circular gears are analyzed, and a set of preferable structural parameters are obtained. Finally, a test bed of this mechanism is developed and the experimental results show that this new beating-up mechanism can achieve the designed dwelling time, namely it can meet the requirements of beating-up process.展开更多
Objective: Acute kidney disease develops 16% - 30% of patients with preoperative impaired renal functions. Our aim of this study was to compare postoperative renal outcomes using two open heart surgery techniques, on-...Objective: Acute kidney disease develops 16% - 30% of patients with preoperative impaired renal functions. Our aim of this study was to compare postoperative renal outcomes using two open heart surgery techniques, on-pump beating heart (OPBH) and conventional on-pump (COP), in patients who have preoperative low glomerular filtration rate (eGFR) as an indicator of creatinine clearance. Methods: From 2004 to 2015, 341 patients with preoperative creatinine clearance were lower than 90 ml/min/1.73m2 were selected for this study. On-Pump beating heart was performed in 111 patients (Group I). Conventional on-pump technique was used in 200 patients. In the remaining patients, we measured postoperative Tumor Necrosis Factor Alpha (TNF-alpha), cardiac troponin I (cTn-I), Brain natriuretic peptid (NT-Pro- BNP), creati-nine (Cr), blood urea nitrogen (BUN) and postoperative eGFR daily until day four after surgery. Results: There were no differences in baseline levels of TNF-alpha, NT-Pro-BNP, BUN, cTn-I, Cr levels between the groups. Cardiopulmonary bypass (CPB) time were much longer and cumulative inotrope use was significantly higher in patients underwent COP (P Conclusion: Our study showed that on-pump beating heart CABG technique provides a morbidity benefit and is associated with a lower risk of peroperative LOS in patients with mild renal disfunction. Our study results suggest that OPBH is superior to the COP in terms of postoperative renal injury and cardiac mediators.展开更多
The Central Statistical Agency （CSA） of Ethiopia included some questions in its 2005 Demographic and Health Survey （DHS） questionnaire, asking for the opinion of men and women if wives beaten by husbands is justif...The Central Statistical Agency （CSA） of Ethiopia included some questions in its 2005 Demographic and Health Survey （DHS） questionnaire, asking for the opinion of men and women if wives beaten by husbands is justified if wives commit some mistakes while they are undertaking their day to day family responsibilities and other personal functions. The sample size was about 14,000 women in the reproductive and productive ages of 15-49 and about 6,000 men in the age brackets of 15-59. The reasons for wife beating by husbands are examined against some selected independent background variables of the sampled men and women respondents, while the dependent variables are the responses to questions of wife beating. With respect to the analytical model, the author decided to focus on some descriptive statistics, such as frequency distributions tables, proportions, comparative analysis, and application of chi-squares （Xz） techniques to examine the variations in the responses of women and men amongst the independent backgrounds.展开更多
Background Off-pump coronary artery bypass grafting (CABG) is becoming increasingly popular world - wide. But it is not always feasible. Current cardioplegic techniques do not consistently avoid myocardial ischemic da...Background Off-pump coronary artery bypass grafting (CABG) is becoming increasingly popular world - wide. But it is not always feasible. Current cardioplegic techniques do not consistently avoid myocardial ischemic damage. So we use on pump beating heart technique to supplement off-pump CABG. Methods Based on 860 off-pump CABG cases between Aug 1998 to Aug 2000. From Aug 1999 to Aug 2000, 46 CABG cases were performed with on pump beating heart technique at Mani-pal Hospital Heart Foundation, Bangalore, India. All surgeries were performed through a median sternotomy. Exposure techniques were tailored to individual vessels and cardiac regions and local immobilization was performed with octopus. Vascular control was achieved with occluders and shunts. Total cardiopulmonary bypass (CPB) was established before or during CABG and normolthemia was used. Results Among 46 on -pump beating heart CABG patients, 26 patients used CPB before or during OP - CABG because of unstable hemodynamics and electric instability , 7 had very deep intramyocardial left anterior descending arteries, 5 patients had poor LV function (LVEF < 30 % ), 8 patients had cardiomegaly. The average number of grafts was 3.5. No operative mortality. Three patients had postoperative myocardial infarction. Anesthetic time 4. 5±1. 2 hours, extubation time 10±2. 5 hours, blood lost 680±230 mL, blood requirement 540±150 mL, preoperative LVEF 50. 3±13 % , postoperative LVEF 64. 1±14 %, ICU stay 1. 5±0. 5 days, hospi- tal stay 9.2±1.8 days. Conclusion Complete coronary revascularization with on pump beating heart is a supplement for off - pump CABG when it is not feasible. It eliminates intraoperative globe myocardial ischemia and avoids transient myocardial injury during cardioplegic arrest and myocardial reperfusion.展开更多
With the experience of over 250 beating hear operations since Feb 1995 westarted minimally invasive revascularization of the LAD(MIDCAB).SinceFeb.1996 we operated upon 182 patients with this procedure Since June1996 w...With the experience of over 250 beating hear operations since Feb 1995 westarted minimally invasive revascularization of the LAD(MIDCAB).SinceFeb.1996 we operated upon 182 patients with this procedure Since June1996 we treated 40 patients with multivessel discase with a Hybridproccdurc(PTCA plus MIDCAB)The age of the patients ranged between 68 and 79 years.29 patients waremaic.28 patiens suffered from a double vessel discase.12 patients fromtriple vessel discase.The left ventricular ejeetion fraction was loss then 40%in 8 cases 2 patients underwent a reoperativc procedure.Further risk factorswere COLD(n=9).recent MI(n=6),renal insufliciency(n=13).Diabeiesinellitus(n-12).The left mammary was prepared in the usual manner.As access wechese a partial inferior sternotomy(n=4)or a lateral minithoracotomy(n=36).The anastomosis was performed on the beating heart.In all patients we conneeted the LIMA to the LAD.All patients survived andcould be discharged on the 6th postoperative day(mean).In two patients arevision due to bleeding became necessary.Two patients reccived a bloodtransfusions.Postoperatively 15 patients reccived a PTCA of the RCX.4 astentimplantation to the Rex.16 a PTCA of the RCA.5 a stentimplantationto the RCA and 3 patients a PTCA of a D1.3 patients developed a falscaneurysm after the cathcter intervention.By performing the nunimally invasive proeedure the trauma caused bycxtracorporeal circulation can be avoided.Through the combination withPTCA a less invasive therapy of coronary multivessel discase becomespossible in select patients.Postoperative complications and hospital stay canbe teduced.展开更多
ZTE Corporation appeared at Expo Comm China2004 with a range of world-leading solutions andapplications stretching across the entiretechnology spectrum-from mobile and NGNrequirements to videoconferencing and
Phase Change Material(PCM)-based cold energy storage system(CESS)can effectively utilize the peak and valley power resources to reduce the excessive dependence on the power grid.In this study,a PCM-based CESS was desi...Phase Change Material(PCM)-based cold energy storage system(CESS)can effectively utilize the peak and valley power resources to reduce the excessive dependence on the power grid.In this study,a PCM-based CESS was designed for cold storage applications.The optimal number of PCM plates was determined through numerical simulations to meet the required cold storage temperature and control time.Additionally,the air temperature field,flow field,and melting characteristics of the PCMplates during the cooling release process were analyzed.The effects of plate positioning and thickness on the cooling release performance were further investigated.The results indicated that when 64PCMplateswere used,the duration formaintaining temperatures below−18℃increased from0.6 h to approximately 16.94 h.During the cooling release process,the temperature field in the cold storage exhibited stratification,and the melting of the PCM plates was non-uniform.Placing the PCM plates at the top or within the interlayers without cargo above proved more effective,with their cooling release power being approximately twice that of the PCM plates placed in the interlayers with cargo above.Furthermore,reducing the thickness of the PCMplates from15 to 7.5mmresulted in a 3.6-h increase in the time below−18℃and a 4.5-h reduction in the time required to reach 80%liquid phase fraction.展开更多
基金Supported by National Natural Science Foundation of China(Grant Nos.551475146,51475366,51075124)
文摘The present research of cold-beating formation mainly focused on roller design and manufacture, kinematics, constitutive relation, metal flow law, thermo-mechanical coupling, surface micro-topography and microstructure evolution. However, the research on surface quality and performance of workpieces in the process of cold-beating is rare. Cold-beating simulation experiment of 1020 steel is conducted at room temperature and strain rates ranging from 2000 to 4000 s^-1 base on the law of plastic forming. According to the experimental data, the model of strain hardening of 1020 steel is established, Scanning Electron Microscopy（SEM） is conducted, the mechanism of the work hardening of 1020 steel is clarified by analyzing microstructure variation of 1020 steel. It is found that the strain rate hardening effect of 1020 steel is stronger than the softening effect induced by increasing temperatures, the process of simulation cold-beating cause the grain shape of 1020 steel significant change and microstructure elongate significantly to form a fibrous tis- sue parallel to the direction of deformation, the higher strain rate, the more obvious grain refinement and the more hardening effect. Additionally, the change law of the work hardening rate is investigated, the relationship between dislocation density and strain, the relationship between work hardening rate and dislocation density is obtained. Results show that the change trend of the work hardening rate of 1020 steel is divided into two stages, the work hardening rate decreases dramatically in the first stage and slowly decreases in the second stage, finally tending toward zero. Dislocation density increases with increasing strain and strain rate, work hardening rate decreases with increasing dislocation density. The research results provide the basis for solving the problem of improving the surface quality and performance of workpieces under cold-beating formation of 1020 steel.
基金supported by National Natural Science Foundation of China(Grant Nos.5107512450975229)Doctoral Foundation of Henan University of Science and Technology of China(Grant No.09001331)
文摘The present research on involute spline cold roll-beating forming is mainly about the principles and motion relations of cold roll-beating,the theory of roller design,and the stress and strain field analysis of cold roll-beating,etc.However,the research on law of metal flow in the forming process of involute spline cold roll-beating is rare.According to the principle of involute spline cold roll-beating,the contact model between the rollers and the spline shaft blank in the process of cold roll-beating forming is established,and the theoretical analysis of metal flow in the cold roll-beating deforming region is proceeded.A finite element model of the spline cold roll-beating process is established,the formation mechanism of the involute spline tooth profile in cold roll-beating forming process is studied,and the node flow tracks of the deformation area are analyzed.The experimental research on the metal flow of cold roll-beating spline is conducted,and the metallographic structure variation,grain characteristics and metal flow line of the different tooth profile area are analyzed.The experimental results show that the particle flow directions of the deformable bodies in cold roll-beating deformation area are determined by the minimum moving resistance.There are five types of metal flow rules of the deforming region in the process of cold roll-beating forming.The characteristics of involute spline cold roll-beating forming are given,and the forming mechanism of involute spline cold roll-beating is revealed.This paper researches the law of metal flow in the forming process of involute spline cold roll-beating,which provides theoretical supports for solving the tooth profile forming quality problem.
文摘针对锅炉过热汽温系统存在的大时延、强非线性和变量耦合等建模难题,建立了一种基于贝叶斯优化时间序列预测神经基扩展分析(neural basis expansion analysis for interpretable time series forecasting,N-BEATS)网络的过热汽温预测模型。针对某600 MW超临界火电机组,结合机理分析确定模型的输入和输出变量,通过性能对比实验优化模型的输入/输出时延阶次、Block类型和激活函数,进一步利用贝叶斯优化算法对模型的超参数进行寻优,并与网格搜索、遗传算法的优化效果进行对比。采用该机组仿真运行数据进行建模实验,结果表明所提模型在预测精度方面优于传统优化方法及主流模型。
文摘Ramsey oscillations typically exhibit an exponential decay envelope due to environmental noise. However,recent experiments have observed nonmonotonic Ramsey fringes characterized by beating patterns, which deviate from the standard behavior. These beating patterns have primarily been attributed to charge-noise fluctuations.In this paper, we have experimentally observed Ramsey fringe with beating pattern for transmon qubits, and traced the origin to electric instruments induced flux noise.
基金supported by the China Scholarship Council (CSC) Local Cooperation Program (No. 202308430176)the National Natural Science Foundation of China (No. 52271177)the Hunan Provincial Natural Science Foundation Regional Joint Fund, China (No. 2023JJ50173)。
文摘The evolution of the S'precipitate in Al−Cu−Mg alloy was investigated using transmission electron microscopy(TEM),high-angle annular dark-field scanning transmission electron microscopy(HAADF−STEM),molecular dynamics(MD)simulations,and other analytical techniques.The precipitation behavior during different aging stages of the supersaturated solid solution formed after rapid cold punching was focused,which induces rapid dissolution of precipitates.The findings reveal that the precipitation sequence is significantly influenced by aging temperature.At higher aging temperatures,which mitigate lattice distortion in the matrix,the precipitation sequence follows the conventional path.Conversely,at lower aging temperatures,where lattice distortion persists,the sequence deviates,suppressing the formation of Guinier−Preston−Bagaryatsky(GPB)zones.MD simulations confirm that the variations in solute atom diffusion rates at different aging temperatures lead to the differences in the S'phase precipitation sequence.
基金a grant from the Science & Technology Development Foundation of Guangdong Health Bureau(No.2006345).
文摘BACKGROUND: Although the use of non-heart beating donors (NHBDs) could bridge the widening gap between organ demand and supply, its application to liver transplantation is limited due to the high incidence of primary graft loss. Prevention of liver injury in NHBDs will benefit the results of transplantation. This study was conducted to evaluate the protective effects of L-arginine on liver grafts from NHBDs. METHODS: One hundred and four Wistar rats were randomly divided into 7 groups: normal control (n=8) controls 1, 2 and 3 (C-1, C-2, C-3, n=16), and experimental 1, 2 and 3 (E-1, E-2, E-3, n=16). For groups C-1 and E-1, C-2 and E-2, and C-3 and E-3, the warm ischemia time was 0, 30, and 45 minutes, respectively. Liver grafts were flushed with and preserved in 4 degrees C Euro-collins solution containing 1 mmol/L L-arginine for 1 hour in each experimental group. Recipients of each experimental group were injected with L-arginine (10 mg/kg body weight) by tail vein 10 minutes before portal vein reperfusion. Donors and recipients of each experimental control group were treated with normal saline. Then transplantation was performed. At 1, 3, and 24 hours after portal vein reperfusion, blood samples were obtained to determine the levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), nitric oxide (NO) and plasma endothelin (ET). At 3 hours after portal vein reperfusion, grafts samples were fixed in 2.5% glutaraldehyde for electron microscopic observation. RESULTS: At I hour after portal vein reperfusion, the levels of NO in groups E-1, E-2, E-3 and C-1, C-2, C-3 were lower, while the levels of plasma ET, serum ALT and AST were higher than those in the normal control group (P<0.05). At 1, 3, and 24 hours, the levels of NO in groups E-1, E-2, E-3 were higher, while the levels of plasma ET, serum ALT and AST were lower than those in the corresponding control groups (C-1, C-2, C-3) (P<0.05). The levels of NO in groups C-2 and C-3 were lower than in group C-1 (P<0.05), and the level of NO in group C-3 was lower than in group C-2 (P<0.05). At 1, 3 and 24 hours, the levels of plasma ET, serum ALT, and AST in groups E-1, E-2, E-3 were lower than those in the corresponding control groups (C-1, C-2, C-3) (P<0.05). The levels of plasma ET, serum ALT, and AST were lower in group C-3 than in groups C-1 and C-2 (P<0.05). Pathological changes in groups E-1, E-2, E-3 were milder than those in the corresponding experimental control groups (C-1, C-2, C-3). CONCLUSIONS: The imbalance between NO and ET plays an important role in the development of ischemia-reperfusion injury of liver grafts from NHBDs. L-arginine can attenuate injury in liver grafts from NHBDs by improving the balance between NO and ET.
文摘In this paper,what causes the setting-on place of woven fabrics without adopting tension compensation is explained by means of experimental methods.Owing to that the main shaft speed and the beating speed of reed can not attain the normal values at setting-on,the warp tension and the beating force of the reed can neither reach the normal level.Therefore,the relative slippage movement of the weft against the warp during beating will be less,while the common movement of the weft together with the warp will be bigger than those at nor-mal running.As a result,the setting-on place is
文摘Diagnostic techniques of CEOF, power spectrum and bandpass filter wave are applied in this paper to analyze the seasonal northward beating of the northern subtropical high using day to day geopotential fields of 2.5 ×2.5 at 500 hPa May through July in 1988 and 1991. It is concluded that it is globally observed that the subtropical high has northward beats that propagate westward; the source of beating mainly lies in the region of Arabian Sea and central Pacific and the sink in eastern Pacific; the seasonal beating is dominated by effects of the disturbance field; low frequency oscillation plays a key role in the beating and the westward propagation so that the difference in the latter in individual years is caused by the varying source of disturbance and the low frequency waves it excites.
文摘In this paper, the intrinsic behavior of rotating Euler Benoulli flexible shafts was studied due to coupled bending and torsional vibrations. The equations of motion of the shaft with unbalanced eccentricity and viscous material damping were derived by the Hamilton principle. The numerical solution was obtained using the perturbation approach and mode assuming method. The influences of the coupled vibrations between the bending and torsion, the rotating speed, material damping and the slenderness ratio of the shaft were analyzed. It is clearly shown that the beating phenomena can occur when the interaction of torsion and flexure is considered.
文摘Objective: To study the outcome of normothermic beating heart pulmonary thromboendarterectomy (PTE) performed in patients with chronic pulmonary thromboembolism. Methodology: A retrospective analysis of 15 patients who underwent PTE under normothermic beating heart cardio-pulmonary bypass from July 2009 to September 2018 was done. The patients were followed up with clinical assessment, transthoracic echocardiography and computerized tomographicangiography (CTA) for 1 month to 82 months. Results: Data were analysed for 15 consecutive patients. Mean age of the patients was 35.28 years and 10 patients were male. Pre-operatively 6 (40%) patients presented with New York Heart Association (NYHA) class II dyspnoea on exertion symptomatology, 7 (47%) were in NHYA class III, and 2 (13%) were in NYHA class IV. The preoperative and postoperative mean pulmonary artery pressures (mPAP) (mmHg) were 36.50 ± 11.3 and 20.21 ± 7.19, the systolic PAPs (mmHg) were 73.35 ± 14.12 and 35.21 ± 7.89 and the diastolic PAPs (mmHg) were 19.28 ± 8.60 and 12.85 ± 7.26 respectively. 2 (13%) patients had Jamieson’s type I and 12 (87%) had Jamieson type II disease. One patient (7%) expired on 9th postoperative day. All the patients had improved pulmonary gas exchange and did not require oxygen supplementation from 5th postoperative day;symptoms improved to NYHA class I & II in 12 (80%) & 3 (20%) of patients respectively. There was no reperfusion pulmonary edema or any neurologic complications. Postoperative echocardiogram showed improved right ventricular function and Computerised Tomographic Angiogram showed completeness of the procedure. Conclusion: Pulmonary thromboendarterectomy under normothermic beating heart cardiopulmonary bypass has good immediate postoperative results with significant progressive improvement in hemodynamics and quality of life during the course of follow-up. The results were not only comparable to those of the procedure done under deep hypothermic circulatory arrest by other centres but also without its associated adverse events. This technique requires more expertise but gives equivalent good results in immediate and short- to mid-term follow-up with less morbidity than the standard procedure, but it requires long-term follow-up to substantiate the evidence.
基金Project supported by the National Basic Research Program of China （Grant No. 201 ICB921603）, the National Natural Science Foundation of China （Grant Nos. 11374126, 10904048, 11074097, 11004079, 11004080, and 11247201）, the China Postdoctoral Science Foundation （Grant Nos. 2011M500924 and 2013T60317）. and the National Fund for Fosterin~ Talents of Basic Science （Grant No. J I 103202）.
文摘We experimentally study the controllable generation of a beating signal using stored light pulses based on electromagnetically induced transparency(EIT) in a solid medium. The beating signal relies on an asymmetric procedure of light storage and retrieval. After storing the probe pulse into the spin coherence under the EIT condition, two-color control fields with opposite detunings instead of the initial control field are used to scatter the stored spin coherence. The controllable beating signal is generated due to alternative constructive and destructive interferences in the retrieved signal intensities. The beating of the two-color control fields is mapped into the beating of weak probe fields by using atomic spin coherence. This beating signal will be important in precise atomic spectroscopy and fast quantum limited measurements.
基金National Natural Science Foundation of China(Nos.51675486 51505239 51575496)
文摘The most important performance of a beating-up mechanism is that the dwelling time of the sley must ensure the completion of the weft insertion. To meet this requirement, a new non-circular combined gear train beating-up mechanism which is composed of two-stage planetary gear trains is proposed. The first-stage is a Fourier planetary gear train and the second-stage is a non-circular planetary gear train. For designing of this new mechanism, the ideal kinematic equations of the sley are constructed first. Then the kinematic model of the first-stage Fourier planetary gear train is established and the reverse solution for the pitch curves of the second-stage non-circular gears is deduced. With a computer-aided design program, the influences of several important parameters on the pitch curves of the second-stage non-circular gears are analyzed, and a set of preferable structural parameters are obtained. Finally, a test bed of this mechanism is developed and the experimental results show that this new beating-up mechanism can achieve the designed dwelling time, namely it can meet the requirements of beating-up process.
文摘Objective: Acute kidney disease develops 16% - 30% of patients with preoperative impaired renal functions. Our aim of this study was to compare postoperative renal outcomes using two open heart surgery techniques, on-pump beating heart (OPBH) and conventional on-pump (COP), in patients who have preoperative low glomerular filtration rate (eGFR) as an indicator of creatinine clearance. Methods: From 2004 to 2015, 341 patients with preoperative creatinine clearance were lower than 90 ml/min/1.73m2 were selected for this study. On-Pump beating heart was performed in 111 patients (Group I). Conventional on-pump technique was used in 200 patients. In the remaining patients, we measured postoperative Tumor Necrosis Factor Alpha (TNF-alpha), cardiac troponin I (cTn-I), Brain natriuretic peptid (NT-Pro- BNP), creati-nine (Cr), blood urea nitrogen (BUN) and postoperative eGFR daily until day four after surgery. Results: There were no differences in baseline levels of TNF-alpha, NT-Pro-BNP, BUN, cTn-I, Cr levels between the groups. Cardiopulmonary bypass (CPB) time were much longer and cumulative inotrope use was significantly higher in patients underwent COP (P Conclusion: Our study showed that on-pump beating heart CABG technique provides a morbidity benefit and is associated with a lower risk of peroperative LOS in patients with mild renal disfunction. Our study results suggest that OPBH is superior to the COP in terms of postoperative renal injury and cardiac mediators.
文摘The Central Statistical Agency （CSA） of Ethiopia included some questions in its 2005 Demographic and Health Survey （DHS） questionnaire, asking for the opinion of men and women if wives beaten by husbands is justified if wives commit some mistakes while they are undertaking their day to day family responsibilities and other personal functions. The sample size was about 14,000 women in the reproductive and productive ages of 15-49 and about 6,000 men in the age brackets of 15-59. The reasons for wife beating by husbands are examined against some selected independent background variables of the sampled men and women respondents, while the dependent variables are the responses to questions of wife beating. With respect to the analytical model, the author decided to focus on some descriptive statistics, such as frequency distributions tables, proportions, comparative analysis, and application of chi-squares （Xz） techniques to examine the variations in the responses of women and men amongst the independent backgrounds.
文摘Background Off-pump coronary artery bypass grafting (CABG) is becoming increasingly popular world - wide. But it is not always feasible. Current cardioplegic techniques do not consistently avoid myocardial ischemic damage. So we use on pump beating heart technique to supplement off-pump CABG. Methods Based on 860 off-pump CABG cases between Aug 1998 to Aug 2000. From Aug 1999 to Aug 2000, 46 CABG cases were performed with on pump beating heart technique at Mani-pal Hospital Heart Foundation, Bangalore, India. All surgeries were performed through a median sternotomy. Exposure techniques were tailored to individual vessels and cardiac regions and local immobilization was performed with octopus. Vascular control was achieved with occluders and shunts. Total cardiopulmonary bypass (CPB) was established before or during CABG and normolthemia was used. Results Among 46 on -pump beating heart CABG patients, 26 patients used CPB before or during OP - CABG because of unstable hemodynamics and electric instability , 7 had very deep intramyocardial left anterior descending arteries, 5 patients had poor LV function (LVEF < 30 % ), 8 patients had cardiomegaly. The average number of grafts was 3.5. No operative mortality. Three patients had postoperative myocardial infarction. Anesthetic time 4. 5±1. 2 hours, extubation time 10±2. 5 hours, blood lost 680±230 mL, blood requirement 540±150 mL, preoperative LVEF 50. 3±13 % , postoperative LVEF 64. 1±14 %, ICU stay 1. 5±0. 5 days, hospi- tal stay 9.2±1.8 days. Conclusion Complete coronary revascularization with on pump beating heart is a supplement for off - pump CABG when it is not feasible. It eliminates intraoperative globe myocardial ischemia and avoids transient myocardial injury during cardioplegic arrest and myocardial reperfusion.
文摘With the experience of over 250 beating hear operations since Feb 1995 westarted minimally invasive revascularization of the LAD(MIDCAB).SinceFeb.1996 we operated upon 182 patients with this procedure Since June1996 we treated 40 patients with multivessel discase with a Hybridproccdurc(PTCA plus MIDCAB)The age of the patients ranged between 68 and 79 years.29 patients waremaic.28 patiens suffered from a double vessel discase.12 patients fromtriple vessel discase.The left ventricular ejeetion fraction was loss then 40%in 8 cases 2 patients underwent a reoperativc procedure.Further risk factorswere COLD(n=9).recent MI(n=6),renal insufliciency(n=13).Diabeiesinellitus(n-12).The left mammary was prepared in the usual manner.As access wechese a partial inferior sternotomy(n=4)or a lateral minithoracotomy(n=36).The anastomosis was performed on the beating heart.In all patients we conneeted the LIMA to the LAD.All patients survived andcould be discharged on the 6th postoperative day(mean).In two patients arevision due to bleeding became necessary.Two patients reccived a bloodtransfusions.Postoperatively 15 patients reccived a PTCA of the RCX.4 astentimplantation to the Rex.16 a PTCA of the RCA.5 a stentimplantationto the RCA and 3 patients a PTCA of a D1.3 patients developed a falscaneurysm after the cathcter intervention.By performing the nunimally invasive proeedure the trauma caused bycxtracorporeal circulation can be avoided.Through the combination withPTCA a less invasive therapy of coronary multivessel discase becomespossible in select patients.Postoperative complications and hospital stay canbe teduced.
文摘ZTE Corporation appeared at Expo Comm China2004 with a range of world-leading solutions andapplications stretching across the entiretechnology spectrum-from mobile and NGNrequirements to videoconferencing and
基金supported by National Natural Science Foundation of China(Nos.51806092,52201410)Non-Carbon Energy Conversion and Utilization Institute under the Shanghai Class IV Peak Disciplinary Development Program,High-End Foreign Experts Recruitment Plan of China(G2022013028L).
文摘Phase Change Material(PCM)-based cold energy storage system(CESS)can effectively utilize the peak and valley power resources to reduce the excessive dependence on the power grid.In this study,a PCM-based CESS was designed for cold storage applications.The optimal number of PCM plates was determined through numerical simulations to meet the required cold storage temperature and control time.Additionally,the air temperature field,flow field,and melting characteristics of the PCMplates during the cooling release process were analyzed.The effects of plate positioning and thickness on the cooling release performance were further investigated.The results indicated that when 64PCMplateswere used,the duration formaintaining temperatures below−18℃increased from0.6 h to approximately 16.94 h.During the cooling release process,the temperature field in the cold storage exhibited stratification,and the melting of the PCM plates was non-uniform.Placing the PCM plates at the top or within the interlayers without cargo above proved more effective,with their cooling release power being approximately twice that of the PCM plates placed in the interlayers with cargo above.Furthermore,reducing the thickness of the PCMplates from15 to 7.5mmresulted in a 3.6-h increase in the time below−18℃and a 4.5-h reduction in the time required to reach 80%liquid phase fraction.
