期刊文献+
共找到464篇文章
< 1 2 24 >
每页显示 20 50 100
Unstable evolution of railway slope under the rainfall-vibration joint action
1
作者 DONG Haoyu WANG Jiading +2 位作者 ZHANG Dengfei LI Lin XU Yuanjun 《Journal of Mountain Science》 SCIE CSCD 2024年第4期1419-1431,共13页
Understanding the unstable evolution of railway slopes is the premise for preventing slope failure and ensuring the safe operation of trains.However,as two major factors affecting the stability of railway slopes,few s... Understanding the unstable evolution of railway slopes is the premise for preventing slope failure and ensuring the safe operation of trains.However,as two major factors affecting the stability of railway slopes,few scholars have explored the unstable evolution of railway slopes under the joint action of rainfall-vibration.Based on the model test of sandy soil slope,the unstable evolution process of slope under locomotive vibration,rainfall,and rainfall-vibration joint action conditions was simulated in this paper.By comparing and analyzing the variation trends of soil pressure and water content of slope under these conditions,the change laws of pore pressure under the influence of vibration and rainfall were explored.The main control factors affecting the stability of slope structure under the joint action conditions were further defined.Combined with the slope failure phenomena under these three conditions,the causes of slope instability resulting from each leading factor were clarified.Finally,according to the above conclusions,the unstable evolution of the slope under the rainfall-vibration joint action was determined.The test results show that the unstable evolution process of sandy soil slope,under the rainfall-vibration joint action,can be divided into:rainfall erosion cracking,vibration promotion penetrating,and slope instability sliding three stages.In the process of slope unstable evolution,rainfall and vibration play the roles of inducing and promoting slide respectively.In addition,the deep cracks,which are the premise for the formation of the sliding surface,and the violent irregular fluctuation of soil pressure,which reflects the near penetration of the sliding surface,constitute the instability characteristics of the railway slope together.This paper reveals the unstable evolution of sandy soil slopes under the joint action of rainfall-vibration,hoping to provide the theoretical basis for the early warning and prevention technology of railway slopes. 展开更多
关键词 Rainfall vibration joint action Small scale model tests unstable evolution process unstable characteristics Inducing sliding and promoting sliding
下载PDF
Analysis of the Nursing Effect of Continuity of Care on Elderly Patients with Coronary Heart Disease Unstable Angina and its Impact on Quality of Life 被引量:1
2
作者 Ling Yan 《Journal of Clinical and Nursing Research》 2024年第2期185-190,共6页
Objective:To analyze the effect of using continuity of care for elderly patients with coronary heart disease(CHD)with unstable angina pectoris(UAP)and its impact on their quality of life.Methods:100 cases of elderly p... Objective:To analyze the effect of using continuity of care for elderly patients with coronary heart disease(CHD)with unstable angina pectoris(UAP)and its impact on their quality of life.Methods:100 cases of elderly patients with CHD with UAP admitted to our hospital from March 2022 to March 2023 were selected and grouped into an observation group and a control group of 50 cases each according to the randomized number table method.The nursing effect and quality of life of the observation group(continuity nursing)and the control group(routine nursing)were compared.Results:The total effective rate of nursing care was 96.00%observation group and 80.00%for the control group,and the differences were significant(χ2=6.061,P<0.05).Patients in the observation group had fewer episodes(1.42±0.21)times/week and a shorter duration(5.46±0.39)min,which were better than the control group(t=3.465,2.973;P<0.05).The depression self-rating depression scale(SDS)score(42.16±6.64)and anxiety self-rating scale(SAS)score(32.26±7.35)in the observation group were lower and the quality of life was higher as compared to that of the control group(P<0.05).Conclusion:Continuous nursing care improved the nursing effect of elderly CHD with UAP patients,promoted the alleviation of UAP symptoms,improved patient mentality,and improved their quality of life.Hence,continuous nursing care possesses significant clinical application value. 展开更多
关键词 Continuity of care ELDERLY Coronary heart disease unstable angina Nursing outcomes Quality of life
下载PDF
Effects of systematic cardiac rehabilitation training in elderly patients with unstable angina following cardiac stent implantation
3
作者 Ling-Ling Yan Xue Yang +1 位作者 Lu Chen Xiao Lu 《World Journal of Clinical Cases》 SCIE 2024年第20期4137-4145,共9页
BACKGROUND Coronary stent implantation is usually used to treat unstable angina to alleviate stenosis or occlusion,promoting blood flow restoration and alleviating symptoms such as myocardial ischemia.And postoperativ... BACKGROUND Coronary stent implantation is usually used to treat unstable angina to alleviate stenosis or occlusion,promoting blood flow restoration and alleviating symptoms such as myocardial ischemia.And postoperative cardiac rehabilitation is essential for enhancing recovery and prognosis.Nevertheless,conventional rehabilitation lacks specificity,particularly for elderly patients with multiple comorbidities and poor compliance,rendering it less effective.AIM To investigate the effects of systematic cardiac rehabilitation training in elderly patients with unstable angina following coronary stenting intervention.METHODS A retrospective enrollment was conducted comprising fifty-four elderly patients with unstable angina pectoris who underwent systematic cardiac rehabilitation training after receiving coronary intervention as the rehabilitation group,while fifty-three elderly patients who received basic nursing and rehabilitation guidance measures after coronary intervention were assigned to the control group.Differences in Seattle Angina Questionnaire scores,survival quality(SF-36)scores,cardiopulmonary exercise function assessment index,echocardiographic cardiac function index,and adverse cardiovascular events were compared between the two groups.RESULTS After intervention,the rehabilitation group observed greater VO2 Max,maximum metabolic equivalent,eft ventricular ejection fraction,left ventricular end-diastolic diameter and smaller left ventricular end-systolic diameter.And the rehabilitation group observed greater scores of physical activity limitation,stable angina pectoris,treatment satisfaction,and SF-36 score.The incidence of adverse cardiovascular events in the two groups,showed no significant difference.CONCLUSION Systematic cardiac rehabilitation following coronary stenting in elderly patients with unstable angina pectoris can enhance cardiac function recovery,consequently enhancing both quality of life and cardiopulmonary exercise tolerance. 展开更多
关键词 Systematicity Cardiac rehabilitation training unstable angina pectoris Coronary stenting implantation Interventional surgery Quality of life Cardiac function Exercise tolerance
下载PDF
Comparative efficacy of proximal femoral nail vs dynamic condylar screw in treating unstable intertrochanteric fractures
4
作者 Ahmed Mohamed Yousif Mohamed Monzir Salih +2 位作者 Mohanad Abdulgadir Ayman E Abbas Duha Lutfi Turjuman 《World Journal of Orthopedics》 2024年第8期796-806,共11页
BACKGROUND Among the most frequent hip fractures are trochanteric fractures,which usually occur from low-energy trauma like minor falls,especially in older people with osteoporotic bones.AIM To evaluate the treatment ... BACKGROUND Among the most frequent hip fractures are trochanteric fractures,which usually occur from low-energy trauma like minor falls,especially in older people with osteoporotic bones.AIM To evaluate the treatment efficacy of dynamic condylar screws(DCS)and proximal femoral nails(PFN)for unstable intertrochanteric fractures.METHODS To find pertinent randomized controlled trials and retrospective observational studies comparing PFN with DCS for the management of unstable femoral intertrochanteric fractures,a thorough search was carried out.For research studies published between January 1996 and April 2024,PubMed,EMBASE,Scopus,Web of Science,Cochrane Library,and Google Scholar were all searched.The complete texts of the papers were retrieved,vetted,and independently examined by two investigators.Disputes were settled by consensus,and any disagreements that persisted were arbitrated by a third author.RESULTS This study included six articles,comprising a total of 173 patients.Compared to the DCS,the PFN had a shorter operation time[mean difference(MD):-41.7 min,95%confidence interval(95%CI):-63.04 to-20.35,P=0.0001],higher success rates with closed reduction techniques[risk ratio(RR):34.05,95%CI:11.12-104.31,P<0.00001],and required less intraoperative blood transfusion(MD:-1.4 units,95%CI:-1.80 to-1.00,P<0.00001).Additionally,the PFN showed shorter fracture union time(MD:-6.92 wk,95%CI:-10.27 to-3.57,P<0.0001)and a lower incidence of reoperation(RR:0.37,95%CI:0.17-0.82,P=0.01).However,there was no discernible variation regarding hospital stay,implant-related complications,and infections.CONCLUSION Compared to DCS,PFN offers shorter operative times,reduces the blood transfusions requirements,achieves higher closed reduction success,enables faster fracture healing,and lowers reoperation incidence. 展开更多
关键词 Intertrochanteric fracture unstable Dynamic condylar screw Proximal femoral nail META-ANALYSIS Comparative study
下载PDF
PFNA2 versus 95 Degree Condylar Blade Plate in the Management of Unstable Trochanteric Fractures
5
作者 Piyush Gadegone Wasudeo Gadegone +1 位作者 Vijayanand Lokhande Virender Kadian 《Open Journal of Orthopedics》 2024年第2期93-104,共12页
Purpose: The proximal femoral nail anti-rotation (PFNA) is known to have advantages in enhancing the anchorage ability of internal fixation in elderly unstable osteoporotic intertrochanteric fracture patients. However... Purpose: The proximal femoral nail anti-rotation (PFNA) is known to have advantages in enhancing the anchorage ability of internal fixation in elderly unstable osteoporotic intertrochanteric fracture patients. However whether it is superior to condylar blade fixation is not clear. This study aimed to determine which treatment has better clinical outcomes in older patients. Materials and Methods: A total of 86 patients over the age of 60 with unstable trochanteric fractures within the past 3 weeks, were included in this prospective study conducted from June 1, 2018, to May 31, 2021. All the intertrochanteric fractures were classified according to AO/OTA classification. Among them, 44 cases were treated with the Proximal Femoral Nail (PFNA2) with or without an augmentation screw, and 42 cases were treated with the Condylar Blade Plate. In addition, the operative time, intraoperative blood loss, intraoperative and postoperative blood transfusion, postoperative weight-bearing time, hospitalization time, Harris score of hip function, Kyle’s criteria and postoperative complications were compared between the two groups. Results: The mean duration of surgery for the PFN group was 66.8 minutes (on average), whereas for the condylar blade plate group, it was 99.30 minutes (on average). The PFNA2 group experienced less blood loss (average of 80 mL) compared to the condylar blade plate group (average of 120 mL). Union and partial weight-bearing occurred earlier in the PFNA2 group (14.1 weeks and 10.6 weeks, respectively) compared to the Condylar blade plate group (18.7 weeks and 15.8 weeks). In two patients from the PFNA2 group, screw backing out and varus collapse complications were encountered;however, these patients remained asymptomatic and did not require revision surgery. In two other patients, screw cut out and breakage of the nail at the helical screw hole leading to non-union of the proximal femur were observed during the nine-month follow-up, necessitating revision surgery with prosthetic replacement. Among the condylar blade plate group, three patients experienced complications, including blade breakage at the blade and plate junction. In two cases, the fracture united in varus, and in one case, the blade cut through, resulting in non-union of the femoral head, which required revision surgery. According to the Harris hip score and Kyle’s criteria, a good-excellent outcome was observed in 92.85% of cases in the PFNA2 group and 90.90% of cases in the condylar blade plate group. Conclusion: Both the Proximal Femoral Nail A2 and Condylar blade plate are effective implants for the treatment of unstable trochanteric fractures. The intramedullary implant promotes biological healing and allows for early ambulation with minimal complications. Similarly satisfactory restoration of anatomy and favorable radiological and functional results can be achieved with the biological fixation provided by the 95-degree condylar blade plate. However, the use of PFNA2 internal fixation technique has the advantage of less trauma in elderly patients than the 95-degree condylar blade plate. 展开更多
关键词 Proximal Femoral Nail Anti-Rotation Condylar Blade Plate Internal Fixation unstable Intertrochanteric Fracture OSTEOPOROTIC
下载PDF
Internal fixator vs external fixator in the management of unstable pelvic ring injuries:A prospective comparative cohort study 被引量:1
6
作者 Mohamed Abo-Elsoud Mostafa I Awad +2 位作者 Mahmoud Abdel Karim Sherif Khaled Mohamed Abdelmoneim 《World Journal of Orthopedics》 2023年第7期562-571,共10页
BACKGROUND Reconstruction of the pelvic ring anatomy in unstable anterior pelvic ring injuries is a significant step to reduce the mortality rate associated with these injuries efficiently.There is a debate on using e... BACKGROUND Reconstruction of the pelvic ring anatomy in unstable anterior pelvic ring injuries is a significant step to reduce the mortality rate associated with these injuries efficiently.There is a debate on using either an anterior subcutaneous pelvis internal fixator(INFIX)or an anterior supra-acetabular external fixator(EXFIX)to manage an unstable anterior pelvic ring fracture.AIM To compare the functional and radiological outcomes and complications of INFIX vs EXFIX in managing unstable pelvic ring injuries.METHODS A prospective cohort study included 54 patients with unstable pelvic ring fractures.The patients were divided into two groups;the INFIX group,in which 30 cases were fixed by INFIX,and the EXFIX group,in which 24 patients were treated by EXFIX.The average age in the EXFIX group was 31.17 years(16-57 years),while in the INFIX group,it was 34.5 years(17-53 years).The study included 20(66.7%)males and 10(33.3%)females in the INFIX group and 10(41.7%)males and 14(58.3%)females in the EXFIX group.The radiological outcomes were evaluated using Matta and Tornetta's score,and the functional outcomes using the Majeed score.RESULTS The results revealed a statistically significant difference between both groups(P=0.013)regarding radiological outcomes,according to Matta and Tornetta's score in favor of the INFIX group.Sitting,standing,and walking abilities were measured at a 3-mo follow-up visit using Majeed score modules.It was significantly better among the INFIX group than the EXFIX group in all three modules.At the final follow-up,both groups had no statistically significant difference according to the Majeed score;92.35 in the INFIX group and 90.99 in the EXFIX group(P=0.513).A lower surgical site infection rate was noticed in the INFIX group(P=0.007).CONCLUSION Anterior subcutaneous pelvis INFIX is associated with better radiological outcomes and a lower infection rate than anterior supra-acetabular EXFIX in managing patients with unstable anterior pelvic ring fractures. 展开更多
关键词 Internal fixator External fixator unstable ANTERIOR PELVIC INJURIES
下载PDF
Structural Determination,Unstable Antiferromagnetism and Transport Properties of Fe-Kagome Y_(0.5)Fe_(3)Sn_(3) Single Crystals
7
作者 刘洋 吕孟 +6 位作者 刘俊艳 张伸 杨金颖 杜志伟 王彬彬 魏红祥 刘恩克 《Chinese Physics Letters》 SCIE EI CAS CSCD 2023年第4期50-55,共6页
Kagome materials have been studied intensively in condensed matter physics.With rich properties,various Kagome materials emerge during this process.Here,we grew single crystals of Y_(0.5)Fe_(3)Sn_(3)and confirmed an Y... Kagome materials have been studied intensively in condensed matter physics.With rich properties,various Kagome materials emerge during this process.Here,we grew single crystals of Y_(0.5)Fe_(3)Sn_(3)and confirmed an YCo_(6)Ge_(6)-type Kagome-lattice structure by detailed crystal structure characterizations.This compound bears an antiferromagnetic ordering at T_(N)= 551 K,and shows a weak ferromagnetism at low temperatures,where an anomalous Hall effect was observed,suggesting the non-zero Berry curvature.With the unstable antiferromagnetic ground state,our systematic investigations make Y_(0.5)Fe_(3)Sn_(3)a potential Kagome compound for Kagome or topological physics. 展开更多
关键词 Crystal structure unstable
下载PDF
Application of lesser trochanteric reduction fixator in the treatment of unstable intertrochanteric fractures
8
作者 Yao-Min Hui Guang Zeng +1 位作者 Pei-Yi Liu Bin Chai 《World Journal of Clinical Cases》 SCIE 2023年第25期5863-5869,共7页
BACKGROUND Closed reduction and internal fixation with intramedullary nails has been widely accepted for treating intertrochanteric fractures.AIM To focus on how to avoid displacement of the lesser trochanter in unsta... BACKGROUND Closed reduction and internal fixation with intramedullary nails has been widely accepted for treating intertrochanteric fractures.AIM To focus on how to avoid displacement of the lesser trochanter in unstable intertrochanteric fractures.METHODS We developed a lesser trochanteric reduction fixator for treating intertrochanteric fractures through fixing the lesser trochanter by combining the loop plate through the fixator after reduction by the reducer.Five patients with intertrochanteric fractures treated with the newly developed lesser trochanteric reduction fixator and loop plate combined with intramedullary nails,and 20 patients with intertrochanteric fractures treated with simple intramedullary nails were selected from December 2020 to March 2021.RESULTS The postoperative Harris hip score was significantly higher in patients treated with the lesser trochanteric reduction fixator than in patients treated without the lesser trochanteric reduction fixator,which indicated that this lesser trochanteric reduction fixator had a positive impact on rehabilitation of the hip joint after surgery and could significantly improve the quality of life of patients.CONCLUSION We fully realize the significance of trochanteric reduction and fixation,namely,reconstruction of structures under pressure,in the treatment of intertrochanteric fractures.As long as the general condition of patients is favorable and they are willing to undergo surgery,fixation of the main fracture end should be performed and the lesser trochanter should be reduced and fixed at the same time. 展开更多
关键词 Lesser trochanteric Intertrochanteric fractures Reduction fixator Loop plate unstable fractures
下载PDF
Effects of surgical treatment modalities on postoperative cognitive function and delirium in elderly patients with extremely unstable hip fractures
9
作者 Xue Zhou Xiao-Hua Chen +3 位作者 Sheng-Hua Li Nan Li Feng Liu Hao-Ming Wang 《World Journal of Psychiatry》 SCIE 2023年第8期533-542,共10页
BACKGROUND As the perioperative risk of elderly patients with extremely unstable hip fractures(EUHFs)is relatively high and therapeutic effect is not satisfactory,new therapeutic strategies need to be proposed urgentl... BACKGROUND As the perioperative risk of elderly patients with extremely unstable hip fractures(EUHFs)is relatively high and therapeutic effect is not satisfactory,new therapeutic strategies need to be proposed urgently to improve the efficacy and clinical outcomes of such patients.AIM To determine the influence of two surgical treatment modalities on postoperative cognitive function(CF)and delirium in elderly patients with EUHFs.METHODS A total of 60 elderly patients consecutively diagnosed with EUHF between September 2020 and January 2022 in the Chongqing University Three Gorges Hospital were included.Of them,30 patients received conventional treatment(control group;general consultation+fracture type-guided internal fixation),and the other 30 received novel treatment(research group;perioperative multidisciplinary treatment diagnosis and treatment+individualized surgical plan+risk prediction).Information on hip function[Harris hip score(HHS)],perioperative risk of orthopedic surgery[Physiological and Operative Severity Score for the Enumeration of Mortality and Morbidity(POSSUM)],CF[Montreal cognitive assessment scale(MoCA)],postoperative delirium[mini-cognitive(Mini-Cog)],adverse events(AEs;internal fixation failure,infection,nonunion,malunion,and postoperative delirium),and clinical indicators[operation time(OT),postoperative hospital length of stay(HLOS),ambulation time,and intraoperative blood loss(IBL)]were collected from both groups for comparative analyses.RESULTS The HHS scores were similar between both groups.The POSSUM score at 6 mo after surgery was significantly lower in the research group compared with the control group,and MoCA and Mini-Cog scores were statistically higher.In addition,the overall postoperative complication rate was significantly lower in the research than in the control group,including reduced OT,postoperative HLOS,ambulation time,and IBL.CONCLUSION The new treatment modality has more clinical advantages over the conventional treatment,such as less IBL,faster functional recovery,more effectively optimized perioperative quality control,improved postoperative CF,mitigated postoperative delirium,and reduced operation-related AEs. 展开更多
关键词 Extremely unstable hip fracture ELDERLY Multidisciplinary treatment Cognitive function Postoperative delirium
下载PDF
Surgical Management of Unstable Superior Femoral Epiphysiolysis with Great Displacement
10
作者 Kalifa Coulibaly Cheick Oumar Sanogo +7 位作者 Mahamdou Diallo Abdoul Kadri Moussa Laye Toure Soumana Traore Aboubacar Diallo Sory Ibrahim Tambassi Souleymane Diallo Ousmane Traoré 《Open Journal of Orthopedics》 2023年第4期173-181,共9页
Introduction: Superior femoral epiphysiolysis (SFE) is a most progressive but sometimes abrupt displacement of the femoral head relative to the superior femoral metaphysis through the cervicocerebral growth plate of t... Introduction: Superior femoral epiphysiolysis (SFE) is a most progressive but sometimes abrupt displacement of the femoral head relative to the superior femoral metaphysis through the cervicocerebral growth plate of the femur. The displacement of the femoral head is most often downward and backward. It is a typical pathology of the pubescent adolescent, most often overweight. It occurs on average at the age of 12 years in girls and 14 years in boys. Unstable forms with large displacements have a high risk of femoral head necrosis and chondrolysis. Although in situ fixation is the generally accepted treatment for minor SFE, the treatment of more severe cases remains controversial. When the extent of the displacement makes it impossible to pass a screw between the femoral neck and the femoral head, the only option is to reduce the displacement. This reduction must be gentle, progressive and limited to the minimum necessary for osteosynthesis. Objective: The aim of the work was to evaluate the results of the technique of progressive reduction of epiphyseal displacement by transtibial traction followed by percutaneous fixation of the femoral head by screw. Patients and Method: This was a retrospective descriptive study over a 10-years period from January 1, 2013 to December 31, 2022. It focused on the surgical treatment of unstable upper femoral epiphysiolysis with large displacement in the orthopaedic trauma department of the University Hospital of Kati. All patients operated on in our department for large displacement SFE were included in this study. Cases of secondary large displacement upper femoral epiphysiolysis and patients who had already undergone surgery on the proximal femur were excluded. Continuous progressive traction on the Boppe splint through a pin under the anterior tibial tuberosity was performed for 15 days in all patients. The hip was flexed to 45° and the knee to 35°. Fixation was performed with one or two screws. No contralateral preventive fixation was performed. Minimum follow-up was one year. Functional outcome was assessed by the Postel Merle d’Aubigné score. Anatomical outcome was assessed by the quality of reduction, the occurrence or non-occurrence of femoral head necrosis, and chondrolysis. Results: We identified nine patients with a mean age of 12.8 years and extremes of 9 and 17 years. There were three boys and six girls. Trauma was mentioned in four cases. The cause was idiopathic in five cases. Functional impotence was complete in all patients. The slippage was acute on a chronic background in all patients. The left side was affected in 7 cases and the right side in 2 cases. The patients were overweight in 7 cases. The patient’s weight was within the normal range in two cases. At final follow-up, all nine patients were asymptomatic. Anatomically, all nine patients had a femoral head free of avascular necrosis. In eight patients, the posterior tilt was absent, identical to that obtained after the traction period. Only one patient had a moderate posterior tilt with a neck uncovering of less than 25%. Functionally, the PMA score was very good in eight cases and good in one case. Conclusion: This study shows that the treatment of acute and unstable forms of upper femoral epiphysiolysis by progressive reduction with transtibial traction can lead to satisfactory results. Reduction in large displacement forms should be gentle, progressive and limited to the minimum necessary for osteosynthesis. Magnetic resonance imaging examination is an essential and indispensable prognostic element. Indications for preventive fixation should be selectively reserved for specific cases. 展开更多
关键词 Epiphysiolysis unstable Femoral Head Continuous Traction
下载PDF
Strategies for Advancing Road Construction Slope Stability: Unveiling Innovative Techniques for Managing Unstable Terrain
11
作者 Guy Oyéniran Adeoti Judicaël Koffi Agbelele +2 位作者 Crespin Prudence Yabi Rufin Nongnidé Kinhoun Éric Adéchina Alamou 《Open Journal of Civil Engineering》 2023年第4期572-616,共45页
This comprehensive review paper explores various aspects of geotechnical engineering, with a focus on the management of unstable terrains, numerical methods for solving complex soil and consolidation problems, rheolog... This comprehensive review paper explores various aspects of geotechnical engineering, with a focus on the management of unstable terrains, numerical methods for solving complex soil and consolidation problems, rheological analysis of suspensions and muddy soils, and stability analysis of slopes. It begins by examining the unique physicochemical properties of cohesive sediments, including cohesion and specific surface area. The temporal evolution of deposit concentration and average bed concentration in unstable terrains is discussed, along with settling behavior of isolated particles and hindered settling using empirical equations. Key sedimentation theories, such as Kynch’s theory, and geotechnical consolidation theories, including Terzaghi’s consolidation equation and Gibson’s theory, are presented. The investigation interrelates these theories and principles to offer a holistic view of managing unstable terrains. It also addresses the challenges associated with experimental determination of constitutive relationships and presents alternative simplification methods proposed by researchers. Additionally, it delves into numerical methods for solving nonlinear partial differential equations governing soil behavior, emphasizing the need for numerical frameworks and discussing various techniques and associated challenges. The rheological analysis section covers material flow behavior, rheological behavior models, and the rheological properties of water and cohesive sediment mixtures. Fundamental geotechnical calculations, constitutive laws, and failure criteria are explained, highlighting their relevance in geotechnical engineering applications. This paper provides a multidimensional perspective on geotechnical engineering, offering valuable insights into soil properties, consolidation processes, numerical methods, rheological analysis, and slope stability assessment for professionals in the field. 展开更多
关键词 Consolidation Processes Managing unstable Terrain Numerical Methods Safety Coefficient Slope Stability Assessment Soil Cohesion
下载PDF
Singular Points, Closed Orbits, Stable Manifolds and Unstable Manifolds of Second Order Autonomous Birkhoff Systems 被引量:1
12
作者 陈向炜 梅凤翔 《Journal of Beijing Institute of Technology》 EI CAS 1998年第4期330-336,共7页
Aim To study singular points, closed orbits, stable manifolds and unstable manifolds of a second order autonomous Birkhoff system. Methods Qualitative methods of ordinary differential equation were used. Results and ... Aim To study singular points, closed orbits, stable manifolds and unstable manifolds of a second order autonomous Birkhoff system. Methods Qualitative methods of ordinary differential equation were used. Results and Conclusion The criteria for singular points, closed orbits and hyperbolic equilibrium points of a second order autonomous Birkhoff system are given. Moreover the stability of equilibria, stable manifolds and unstable manifolds are obtained. 展开更多
关键词 Birkhoff system singular point closed orbit stable manifold unstable manifold
下载PDF
A method for prediction of unstable deformation in hot forging process by simulation
13
作者 鲁世强 李鑫 +2 位作者 王克鲁 刘诗彪 傅铭旺 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2013年第12期3739-3747,共9页
A method is proposed for prediction of the unstable deformation in hot forging process using both the determined thermomechnical parameter windows of the unstable deformation zones and finite element simulation. Takin... A method is proposed for prediction of the unstable deformation in hot forging process using both the determined thermomechnical parameter windows of the unstable deformation zones and finite element simulation. Taking Ti-6.5Al-3.5Mo-1.5Zr-0.3Si alloy as the testing material, the thermomechnical parameter windows of the unstable deformation zones for the Ti-alloy are integrated into a commercial finite element simulation software platform. The distribution and variation of the unstable deformation zones of the alloy in hot compression process are simulated and predicted using the tailor-made finite element codes in the finite element platform. The simulation results tally with the physical experiments and the proposed method for simulation and prediction of the unstable deformation is thus verified and its efficiency is validated. 展开更多
关键词 instability map unstable deformation instability deformation simulation Ti-6.5Al-3.5Mo-1.5Zr-0.3Si titanium alloy
下载PDF
Oscillation of Unstable Second Order Neutral Differential Equations with Positive and Negative Coefficients
14
作者 徐继军 《Chinese Quarterly Journal of Mathematics》 CSCD 2000年第3期72-75,共4页
This paper discusses a class of unstable second order neutral differential equations with positive and negative coeffcients. Sufficient conditions for all bounded solutions of the equations to be oscillatory are obtai... This paper discusses a class of unstable second order neutral differential equations with positive and negative coeffcients. Sufficient conditions for all bounded solutions of the equations to be oscillatory are obtained. 展开更多
关键词 neutral equation unstable OSCILLATION
下载PDF
Seismological method for prediction of areal rockbursts in deep mine with seismic source mechanism and unstable failure theory 被引量:23
15
作者 唐礼忠 XIA K W 《Journal of Central South University》 SCIE EI CAS 2010年第5期947-953,共7页
The research on the rock burst prediction was made on the basis of seismology,rock mechanics and the data from Dongguashan Copper Mine(DCM) ,the deepest metal mine in China.The seismic responses to mining in DCM were ... The research on the rock burst prediction was made on the basis of seismology,rock mechanics and the data from Dongguashan Copper Mine(DCM) ,the deepest metal mine in China.The seismic responses to mining in DCM were investigated through the analyses of the spatio-temporal distribution of hypocenters,apparent stress and displacement of seismic events,and the process of the generation of hazardous seismicity in DCM was studied in the framework of the theory of asperity in the seismic source mechanism.A method of locating areas with hazardous seismicity and a conceptual model of hazardous seismic nucleation in DCM were proposed.A criterion of rockburst prediction was analyzed theoretically in the framework of unstable failure theories,and consequently,the rate of change in the ratio of the seismic stiffness of rock in a seismic nucleation area to that in surrounding area,dS/dt,is defined as an index of the rockburst prediction.The possibility of a rockburst will increase if dS/dt>0,and the possibility of rock burst will decrease if dS/dt<0.The correctness of these methods is demonstrated by analyses of rock failure cases in DCM. 展开更多
关键词 areal rockburst prediction seismic source mechanism unstable failure deep mine seismic stiffness seismic nucleation
下载PDF
MmWave Beamforming for UAV Communications with Unstable Beam Pointing 被引量:8
16
作者 Weizhi Zhong Lei Xu +2 位作者 Qiuming Zhu Xiaomin Chen Jianjiang Zhou 《China Communications》 SCIE CSCD 2019年第1期37-46,共10页
Millimeter wave(mmWave) communications of unmanned aerial vehicles(UAVs) have drawn dramatic attentions for its flexibility on a variety of applications.Recently,channel tracking base on the spatial features has been ... Millimeter wave(mmWave) communications of unmanned aerial vehicles(UAVs) have drawn dramatic attentions for its flexibility on a variety of applications.Recently,channel tracking base on the spatial features has been proposed to solve the problem of beam misalignments due to the UAV navigation.However,unstable beam pointing caused by the non-ideal beam tracking environment may impact the performance of mmWave systems significantly.In this paper,an improved beamforming method is presented to overcome this shortcoming.Firstly,the effect of the beam deviation is analyzed through the establishment of the equivalent data rate.Then,combining the quantification of spatial angle and the improved orthogonal matching pursuit(OMP) algorithm,an optimized beam corresponding to the beam deviation is obtained.Simulation results show that the optimized beam of the proposed approach can effectively improve the spectral efficiency without improving the complexity when the beam pointing is unstable. 展开更多
关键词 UAV COMMUNICATIONS mmWave BEAMFORMING unstable BEAM POINTING BEAM tracking orthogonal matching pursuit(OMP)
下载PDF
Identifying Metabolite and Protein Biomarkers in Unstable Angina In-patients by Feature Selection Based Data Mining Method 被引量:8
17
作者 SHI Cheng-he ZHAO Hui-hui +8 位作者 HOU Na CHEN Jian-xin SHI Qi XU Xue-gong WANG Juan ZHENG Cheng-long ZHAO Ling-yan YANG Yi WANG Wei 《Chemical Research in Chinese Universities》 SCIE CAS CSCD 2011年第1期87-93,共7页
Unstable angina(UA) is the most dangerous type of Coronary Heart Disease(CHD) to cause more and more mortal and morbid world wide. Identification of biomarkers for UA at the level of proteomics and metabolomics is... Unstable angina(UA) is the most dangerous type of Coronary Heart Disease(CHD) to cause more and more mortal and morbid world wide. Identification of biomarkers for UA at the level of proteomics and metabolomics is a better avenue to understand the inner mechanism of it. Feature selection based data mining method is better suited to identify biomarkers of UA. In this study, we carried out clinical epidemiology to collect plasmas of UA in-patients and controls. Proteomics and metabolomics data were obtained via two-dimensional difference gel electrophoresis and gas chromatography techniques. We presented a novel computational strategy to select biomarkers as few as possible for UA in the two groups of data. Firstly, decision tree was used to select biomarkers for UA and 3-fold cross validation was used to evaluate computational performanees for the three methods. Alternatively, we combined inde- pendent t test and classification based data mining method as well as backward elimination technique to select, as few as possible, protein and metabolite biomarkers with best classification performances. By the method, we selected 6 proteins and 5 metabolites for UA. The novel method presented here provides a better insight into the pathology of a disease. 展开更多
关键词 BIOMARKER Metabolomics PROTEOME Feature selection Data mining unstable angina
下载PDF
Left atrial area index predicts adverse cardiovascular events in patients with unstable angina pectoris 被引量:6
18
作者 Yi-Fan LI Wei-Hong LI +4 位作者 Zhao-Ping LI Xin-Heng FENG Wei-Xian XU Shao-Min CHEN Wei GAO 《Journal of Geriatric Cardiology》 SCIE CAS CSCD 2016年第8期652-657,共6页
Background The left atrial size has been considered as a useful marker of adverse cardiovascular outcomes. However, it is not well known whether left atrial area index (LAAI) has predictive value for prognosis in pa... Background The left atrial size has been considered as a useful marker of adverse cardiovascular outcomes. However, it is not well known whether left atrial area index (LAAI) has predictive value for prognosis in patients with unstable angina pectoris (UAP). This study was aimed to assess the association between LAAI and outcomes in UAP patients. Methods We enrolled a total of 391 in-hospital patients diag- nosed as UAP. Clinical and echocardiographic data at baseline were collected. The patients were followed for the development of ad- verse cardiovascular (CV) events, including hospital readmission for angina pectoris, acute myocardial infarction (AMI), congestive heart failure (CHF), stroke and all-cause mortality. Results During a mean follow-up time of 26.3±8.6 months, 98 adverse CV events occurred (84 hospital readmission for angina pectoris, four AMI, four CHF, one stroke and five all-cause mortality). In a multivariate Cox model, LAAI [OR: 1.140, 95% CI: 1.01±1.279, P = 0.026], diastolic blood pressure (OR: 0.976, 95% CI: 0.956-0.996, P = 0.020) and pulse pressure (OR 1.020, 95% CI: 1.007-1.034, P = 0.004) were independent predictors for adverse CV events in UAP patients. Conclusions LAAI is a predictor of adverse CV events independent of clinical and other echocardiographic parameters in UAP patients. 展开更多
关键词 Adverse cardiovascular events Left atrial area index Prognostic factor unstable angina pectoris
下载PDF
Unstable Tropical Air-Sea Interaction Waves and Their Physical Mechanisms 被引量:6
19
作者 张人禾 巢纪平 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 1993年第1期61-70,共10页
In this paper, the tropical air-sea interaction is discussed by using a simple air-sea coupled model, in which the inertia-gravity waves are filtered off and only the equatorial Rossby waves are reserved in both the a... In this paper, the tropical air-sea interaction is discussed by using a simple air-sea coupled model, in which the inertia-gravity waves are filtered off and only the equatorial Rossby waves are reserved in both the atmosphere and the ocean. There exist two kinds of air-sea interaction waves in the coupled model, that is, the high-frequency fast waves and the low-frequency slow waves. The phase speed of the fast waves is westward and the frequencies are close to those of the equatorial Rossby waves in the atmosphere. The slow waves propagate westward in the part of short wavelengths and eastward in that of long wavelengths. There exist instabilities for both the westward and eastward propagating slow waves. If the fast waves are filtered off, there is little effect on the slow waves which have great influence on the long range process in the tropical air-sea coupled system. According to the tropical air-sea interaction waves we obtain here, a possible explanation to the propagating process of ENSO events is given. 展开更多
关键词 unstable Tropical Air-Sea Interaction Waves and Their Physical Mechanisms ZHANG ENSO
下载PDF
Asymmetrical traumatic bilateral hip dislocations with hemodynamic instability and an unstable pelvic ring: Case report and review of literature 被引量:4
20
作者 Kai Huang Grey Giddins +4 位作者 Jian-Fang Zhang Jian-Wei Lu Jun-Ming Wan Peng-Li Zhang Shao-Yu Zhu 《World Journal of Clinical Cases》 SCIE 2018年第5期94-98,共5页
Simultaneous anterior and posterior traumatic dislocations of both hips are very rare. Only 33 cases have been previously reported in the English language literature. Although they were all due to high-energy injuries... Simultaneous anterior and posterior traumatic dislocations of both hips are very rare. Only 33 cases have been previously reported in the English language literature. Although they were all due to high-energy injuries, they were hemodynamically stable and had a stable pelvic ring. We report a unique case of asymmetrical hip dislocations with an unstable pelvic ring and hemodynamic instability. A 40-year-old man was injured in a high-energy motor vehicle accident. He was hemodynamically unstable when he presented in the emergency department. Radiolographs showed asymmetrical dislocations of both hips with an unstable pelvic ring. Under general anesthesia, he had closed reduction of the dislocations of both hips, followed by temporary stabilization with an external fixator. Transcatheter arterial embolization was performed to stop active pelvic bleeding. Delayed open reduction and internal fixation was performed 12 d later with anterior and posterior plates. The patient recovered well with an uneventful post-operative course. Asymmetrical bilateral hip dislocations with pelvic ring instability caused by trauma, as presented in this case, is very rare and potentially life threatening. Prompt treatment can give a good outcome. 展开更多
关键词 Asymmetrical BILATERAL HIP dislocations unstable PELVIC ring HEMODYNAMIC instability
下载PDF
上一页 1 2 24 下一页 到第
使用帮助 返回顶部