Unmanned Aerial Vehicles(UAVs)have become integral components in smart city infrastructures,supporting applications such as emergency response,surveillance,and data collection.However,the high mobility and dynamic top...Unmanned Aerial Vehicles(UAVs)have become integral components in smart city infrastructures,supporting applications such as emergency response,surveillance,and data collection.However,the high mobility and dynamic topology of Flying Ad Hoc Networks(FANETs)present significant challenges for maintaining reliable,low-latency communication.Conventional geographic routing protocols often struggle in situations where link quality varies and mobility patterns are unpredictable.To overcome these limitations,this paper proposes an improved routing protocol based on reinforcement learning.This new approach integrates Q-learning with mechanisms that are both link-aware and mobility-aware.The proposed method optimizes the selection of relay nodes by using an adaptive reward function that takes into account energy consumption,delay,and link quality.Additionally,a Kalman filter is integrated to predict UAV mobility,improving the stability of communication links under dynamic network conditions.Simulation experiments were conducted using realistic scenarios,varying the number of UAVs to assess scalability.An analysis was conducted on key performance metrics,including the packet delivery ratio,end-to-end delay,and total energy consumption.The results demonstrate that the proposed approach significantly improves the packet delivery ratio by 12%–15%and reduces delay by up to 25.5%when compared to conventional GEO and QGEO protocols.However,this improvement comes at the cost of higher energy consumption due to additional computations and control overhead.Despite this trade-off,the proposed solution ensures reliable and efficient communication,making it well-suited for large-scale UAV networks operating in complex urban environments.展开更多
Hydroelectric power production from Garafiri dam and rainfall are essential elements with the observation of hydroelectric power production in West African power system,particularly in Guinea.This article focuses on t...Hydroelectric power production from Garafiri dam and rainfall are essential elements with the observation of hydroelectric power production in West African power system,particularly in Guinea.This article focuses on the study and the influence of climate variability on hydroelectric power production at Garafiri dam over 16-year period(2008-2023).The aim of this work is to show the correlation between rainfall anomalies and hydroelectric power production at Garafiri dam.The method used consists of calculating precipitation anomalies at Garafiri site and those for the production of hydroelectric power from Garafiri dam over the study period.This approach led us to calculate the anomalies,leading to the study on climatic variability,in order to establish correlation between rainfall and hydroelectric power dam’s production.The trend with the correlation found made it possible to carry out a significance test between these two variables.These results clearly show that rainfall in Garafiri site increases hydroelectric power production and vice versa,which explains the interdependence between these two parameters,i.e.climatic variability and hydroelectric power production.展开更多
The association between Vitamin D and IBS has attracted growing interest because of vitamin D’s involvement in immune system function and reduction of inflammation. IBS, a prevalent gastrointestinal condition marked ...The association between Vitamin D and IBS has attracted growing interest because of vitamin D’s involvement in immune system function and reduction of inflammation. IBS, a prevalent gastrointestinal condition marked by symptoms such as stomach pain, bloating, and changed bowel habits, implies that sufficient levels of Vitamin D may impact the symptomatology and quality of life associated with IBS. This review aimed to unveil current insights on vitamin D intake, status and symptoms of irritable bowel syndrome. A search was conducted on Embase, Scopus, Medline, and Cochrane Library, as well as a reference list of relevant studies. This paper also examined the current therapeutic practices for using vitamin D in the management of IBS. Although several studies demonstrate a positive association between vitamin D administration and the alleviation of IBS symptoms, the data is not yet definitive. Moreover, the review emphasised the necessity for additional rigorous clinical studies to determine a definitive therapeutic function of vitamin D in IBS based on the literature. The role of vitamin D in the modulation of gut health, particularly in IBS, has garnered significant attention due to its potential impact on both inflammation and the integrity of the gut barrier. Vitamin D, acting as a hormone precursor, is recognised for its crucial involvement in maintaining calcium balance and promoting bone health.展开更多
Changdao Island,a hidden gem in east China’s Shandong Province,features breathtaking nature.As the sun cuddles the horizon,the island’s azure sky provides a flawless backdrop to an exquisite panorama.Jagged cliffs c...Changdao Island,a hidden gem in east China’s Shandong Province,features breathtaking nature.As the sun cuddles the horizon,the island’s azure sky provides a flawless backdrop to an exquisite panorama.Jagged cliffs carved by centuries of endless waves stand guard along the shoreline,their rocky silhouettes seemingly frozen in time,summoning ancient majesty.Against this dramatic backdrop,flocks of seagulls take flight,their ivory wings catching the golden hues of the sun,creating an enchanting ballet in the sky.The air is filled with the gentle cries of these graceful birds,enhancing the island’s serenity.This harmonious blend of nature’s elements,from the sapphire sea to the towering cliffs and the mesmerizing flight of seagulls,makes Changdao Island an artistic masterpiece painted by the hand of mother nature herself.展开更多
The confidentiality of pseudonymous authentication and secure data transmission is essential for the protection of information and mitigating risks posed by compromised vehicles.The Internet of Vehicles has meaningful...The confidentiality of pseudonymous authentication and secure data transmission is essential for the protection of information and mitigating risks posed by compromised vehicles.The Internet of Vehicles has meaningful applications,enabling connected and autonomous vehicles to interact with infrastructure,sensors,computing nodes,humans,and fellow vehicles.Vehicular hoc networks play an essential role in enhancing driving efficiency and safety by reducing traffic congestion while adhering to cryptographic security standards.This paper introduces a privacy-preserving Vehicle-to-Infrastructure authentication,utilizing encryption and the Moore curve.The proposed approach enables a vehicle to deduce the planned itinerary of Roadside Units(RSUs)before embarking on a journey.Crucially,the Certification Authority remains unaware of the specific route design,ensuring privacy.The method involves transforming all Roadside Units(RSUs)in a region into a vector,allowing for instant authentication of a vehicle’s route using RSU information.Real-world performance evaluations affirm the effectiveness of the proposed model.展开更多
Based on research studies currently being carried out at Dalian University of Technology, some important aspects for the earthquake safety assessmcnt of concrete dams are reviewed and discussed. First, the rate-depend...Based on research studies currently being carried out at Dalian University of Technology, some important aspects for the earthquake safety assessmcnt of concrete dams are reviewed and discussed. First, the rate-dependent behavior of concrcte subjected to earthquake loading is examined, emphasizing the properties of concrete under cyclic and biaxial loading conditions. Second, a modified four-parameter Hsieh-Ting-Chen viscoplastic consistency model is developed to simulate the rate-dependent behavior of concrete. The earthquake response of a 278m high arch dam is analyzed, and the results show that the strain-rate effects become noticeable in the inelastic range, Third, a more accurate non-smooth Newton algorithm for the solution of three-dimensional frictional contact problems is developed to study the joint opening effects of arch dams during strong earthquakes. Such effects on two nearly 300m high arch dams have been studied. It was found that the canyon shape has great influence on the magnitude and distribution of the joint opening along the dam axis. Fourth, the scaled boundary finite element method presented by Song and Wolf is employed to study the dam-reservoir-foundation interaction effects of concrete dams. Particular emphases were placed on the variation of foundation stiffness and the anisotropic behavior of the foundation material on the dynamic response of concrete dams. Finally, nonlinear modeling of concrete to study the damage evolution of concrete dams during strong earthquakes is discussed. An elastic-damage mechanics approach for damage prediction of concrete gravity dams is described as an example. These findings are helpful in understanding the dynamic behavior of concrete dams and promoting the improvement of seismic safety assessment methods.展开更多
Improving vehicle fuel consumption,performance and aerodynamic efficiency by drag reduction especially in heavy vehicles is one of the indispensable issues of automotive industry.In this work,the effects of adding app...Improving vehicle fuel consumption,performance and aerodynamic efficiency by drag reduction especially in heavy vehicles is one of the indispensable issues of automotive industry.In this work,the effects of adding append devices like deflector and cab vane corner on heavy commercial vehicle drag reduction were investigated.For this purpose,the vehicle body structure was modeled with various supplementary parts at the first stage.Then,computational fluid dynamic(CFD) analysis was utilized for each case to enhance the optimal aerodynamic structure at different longitudinal speeds for heavy commercial vehicles.The results show that the most effective supplementary part is deflector,and by adding this part,the drag coefficient is decreased considerably at an optimum angle.By adding two cab vane corners at both frontal edges of cab,a significant drag reduction is noticed.Back vanes and base flaps are simple plates which can be added at the top and side end of container and at the bottom with specific angle respectively to direct the flow and prevent the turbulence.Through the analysis of airflow and pressure distribution,the results reveal that the cab vane reduces fuel consumption and drag coefficient by up to 20 % receptively using proper deflector angle.Finally,by adding all supplementary parts at their optimized positions,41% drag reduction is obtained compared to the simple model.展开更多
Diagnostic imaging plays a key role in the diagnosis and management of inflammatory bowel disease(IBD). However due to the relapsing nature of IBD, there is growing concern that IBD patients may be exposed to potentia...Diagnostic imaging plays a key role in the diagnosis and management of inflammatory bowel disease(IBD). However due to the relapsing nature of IBD, there is growing concern that IBD patients may be exposed to potentially harmful cumulative levels of ionising radiation in their lifetime, increasing malignant potential in a population already at risk. In this review we explore the proportion of IBD patients exposed to high cumulative radiation doses, the risk factors associated with higher radiation exposures, and we compare conventional diagnostic imaging with newer radiation-free imaging techniques used in the evaluation of patients with IBD. While computed tomography(CT) performs well as an imaging modality for IBD, the effective radiation dose is considerably higher than other abdominal imaging modalities. It is increasingly recognised that CT imaging remains responsible for the majority of diagnostic medical radiation to which IBD patients are exposed. Magnetic resonance imaging(MRI) and small intestine contrast enhanced ultrasonography(SICUS) have now emerged as suitable radiation-free alternatives to CT imaging, with comparable diagnostic accuracy. The routine use of MRI and SICUS for the clinical evaluation of patients with known or suspected small bowel Crohn's disease is to be encouraged wherever possible. More provision is needed for out-of-hours radiation-free imaging modalities to reduce the need for CT.展开更多
To gain insight into the inelastic behavior of piles, the response of a vertical pile embedded in dry sand and subjected to cyclic lateral loading was studied experimentally in centrifuge tests conducted in Laboratoir...To gain insight into the inelastic behavior of piles, the response of a vertical pile embedded in dry sand and subjected to cyclic lateral loading was studied experimentally in centrifuge tests conducted in Laboratoire Central des Ponts et Chaussees. Three types of cyclic loading were applied, two asymmetric and one symmetric with respect to the unloaded pile. An approximately square-root variation of soil stiffness with depth was obtained from indirect in-flight density measurements, laboratory tests on reconstituted samples, and well-established empirical correlations. The tests were simulated using a cyclic nonlinear Winkler spring model, which describes the full range of inelastic phenomena, including separation and re-attachment of the pile from and to the soil. The model consists of three mathematical expressions capable of reproducing a wide variety of monotonic and cyclic experimentalp-y curves. The physical meaning of key model parameters is graphically explained and related to soil behavior. Comparisons with the centrifuge test results demonstrate the general validity of the model and its ability to capture several features of pile-soil interaction, including： soil plastification at an early stage of loading, ＂pinching＂ behavior due to the formation of a relaxation zone around the upper part of the pile, and stiffness and strength changes due to cyclic loading. A comparison of the p-y curves derived from the test results and the proposed model, as well as those from the classical curves of Reese et al. （1974） for sand, is also presented.展开更多
Gastric cancer poses a significant public health problem, especially in the Far East, due to its high incidence in these areas. Surgical treatment and guidelines have been markedly different in the West, but nowadays ...Gastric cancer poses a significant public health problem, especially in the Far East, due to its high incidence in these areas. Surgical treatment and guidelines have been markedly different in the West, but nowadays this debate is apparently coming to an end. Laparoscopic surgery has been employed in the surgical treatment of gastric cancer for two decades now, but with controversies about the extent of resection and lymphadenectomy. Despite these difficulties, the apparent advantages of the laparoscopic approach helped its implementation in early stage and distal gastric cancer, with an increase on the uptake for distal gastrectomy for more advanced disease and total gastrectomy. Nevertheless, there is no conclusive evidence about the laparoscopic approach yet. In this review article we present and analyse the current status of laparoscopic surgery in the treatment of gastric cancer.展开更多
A new approach to evaluate the extreme value distribution （EVD） of the response and reliability of general multi-DOF nonlinear stochastic structures is proposed. The approach is based on the recently developed proba...A new approach to evaluate the extreme value distribution （EVD） of the response and reliability of general multi-DOF nonlinear stochastic structures is proposed. The approach is based on the recently developed probability density evolution method, which enables the instantaneous probability density functions of the stochastic responses to be captured. In the proposed method, a virtual stochastic process is first constructed to satisfy the condition that the extreme value of the response equals the value of the constructed process at a certain instant of time. The probability density evolution method is then applied to evaluate the instantaneous probability density function of the response, yielding the EVD. The reliability is therefore available through a simple integration over the safe domain. A numerical algorithm is developed using the Number Theoretical Method to select the discretized representative points. Further, a hyper-ball is imposed to sieve the points from the preceding point set in the hypercube. In the numerical examples, the EVD of random variables is evaluated and compared with the analytical solution. A frame structure is analyzed to capture the EVD of the response and the dynamic reliability. The investigations indicate that the proposed approach provides reasonable accuracy and efficiency.展开更多
An analytical method to study the seismic response of a bridge pier supported on a rigid caisson foundation embedded in a deep soil stratum underlain by a homogeneous half space is developed. The method reproduces the...An analytical method to study the seismic response of a bridge pier supported on a rigid caisson foundation embedded in a deep soil stratum underlain by a homogeneous half space is developed. The method reproduces the kinematic and inertial responses, using translational and rotational distributed Winkler springs and dashpots to simulate the soil-caisson interaction. Closed-form solutions are given in the frequency domain for vertical harmonic S-wave excitation. Comparison with results from finite element （FE） analysis and other available solutions demonstrates the reliability of the model. Results from parametric studies are given for the kinematic and inertial responses. The modification of the fundamental period and damping ratio of the bridge due to soil-structure interaction is graphically illustrated.展开更多
AIM To compare outcomes in patients undergoing rectal resection by robotic total meso-rectal excision(RTME) vs laparoscopic total meso-rectal excision(LTME).METHODS Standard medical electronic databases such as Pub-Me...AIM To compare outcomes in patients undergoing rectal resection by robotic total meso-rectal excision(RTME) vs laparoscopic total meso-rectal excision(LTME).METHODS Standard medical electronic databases such as Pub-Med, MEDLINE, EMBASE and Scopus were searched to find relevant articles. The data retrieved from all types of included published comparative trials in pati-ents undergoing RTME vs LTME was analysed using the principles of meta-analysis. The operative, post-operative and oncological outcomes were evaluated to assess the effectiveness of both techniques of TME. The summated outcome of continuous variables was expressed as standardized mean difference(SMD) and dichotomous data was presented in odds ratio(OR).RESULTS One RCT(ROLARR trial) and 27 other comparative studies reporting the non-oncological and oncological outcomes following RTME vs LTME were included in this review. In the random effects model analysis using the statistical software Review Manager 5.3, the RTME was associated with longer operation time(SMD, 0.46; 95%CI: 0.25, 0.67; z = 4.33; P = 0.0001), early passage of first flatus(P = 0.002), lower risk of conversion(P = 0.00001) and shorter hospitalization(P = 0.01). The statistical equivalence was seen between RTME and LTME for non-oncological variables like blo-od loss, morbidity, mortality and re-operation risk. The oncological variables such as recurrence(P = 0.96), number of harvested nodes(P = 0.49) and positive circumferential resection margin risk(P = 0.53) were also comparable in both groups. The length of distal resection margins was similar in both groups. CONCLUSION RTME is feasible and oncologically safe but failed to demonstrate any superiority over LTME for many sur-gical outcomes except early passage of flatus, lower risk of conversion and shorter hospitalization.展开更多
Radiotherapy(RT) after tumorectomy in early breast cancer patients is an established treatment modality which conventionally takes 6-7 wk to complete.Shorter RT schedules have been tested in large multicentre randomiz...Radiotherapy(RT) after tumorectomy in early breast cancer patients is an established treatment modality which conventionally takes 6-7 wk to complete.Shorter RT schedules have been tested in large multicentre randomized trials and have shown equivalent results to that of standard RT(50 Gy in 25 fractions) in terms of local tumor control,patient survival and late post-radiation effects.Some of those trials have now completed 10 years of follow-up with encouraging results for treatments of 3-4 wk and a total RT dose to the breast of 40-42.5 Gy with or without boost.A reduction of 50% in treatment time makes those RT schedules attractive for both patients and health care providers and would have a significant impact on daily RT practice around the world,as it would accelerate patient turnover and save health care resources.However,in hypofractionated RT,a higher(than the conventional 1.8-2 Gy) dose per fraction is given and should be managed with caution as it could result in a higher rate of late postradiation effects in breast,heart,lungs and the brachial plexus.It is therefore advisable that both possible dose inhomogeneity and normal tissue protection should be taken into account and the appropriate technology such as three-dimensional/intensity modulated radiation therapy employed in clinical practice,when hypofractionation is used.展开更多
Massive segmental bone loss due to chronic osteomyelitis represents a considerable challenge to orthopedic surgeons and is a limb threatening condition.The only option available in such a clinical situation is segment...Massive segmental bone loss due to chronic osteomyelitis represents a considerable challenge to orthopedic surgeons and is a limb threatening condition.The only option available in such a clinical situation is segment transport using the Ilizarov technique of distraction osteogenesis;yet the most common problem in cases of bone transport with the Ilizarov technique in massive bone loss,is the long duration of the fixator.In addition to autologous bone grafting,several mechanical,biologic,and external physical treatment modalities may be employed to promote bone formation and maturation during segment transport in osteomyelitis patients.Mechanical approaches include compressive loading of the distraction regenerate,increased frequency of small increments of distraction,and compression-distraction.Intramedullary nailing and hemicorticotomy can reduce the time in external fixation;however,these techniques are associated with technical difficulties and complications.Exogenous application of low-intensity pulsed ultrasound or pulsed electromagnetic fields may shorten the duration of external fixation.Other promising modalities include diphosphonates,physician-directed use(off-label use)of bone morphogenetic proteins,and local injection of bone marrow aspirate and platelet gel at the osteotomy site.Well-designed clinical studies are needed to establish safe and effective guidelines for various modalities to enhance new bone formation during distraction osteogenesis after segment transfer.展开更多
This is the second paper of two, which describe the results of an integrated research effort to develop a four-step simplified approach for design of raft foundations against dip-slip （normal and thrust） fault ruptu...This is the second paper of two, which describe the results of an integrated research effort to develop a four-step simplified approach for design of raft foundations against dip-slip （normal and thrust） fault rupture. The first two steps dealing with fault rupture propagation in the free-field were presented in the companion paper. This paper develops an approximate analytical method to analyze soil-foundation-structure interaction （SFSI）, involving two additional phenomena： （i） fault rupture diversion （Step 3）; and （ii） modification of the vertical displacement profile （Step 4）. For the first phenomenon （Step 3）, an approximate energy-based approach is developed to estimate the diversion of a fault rupture due to presence of a raft foundation. The normalized critical load for complete diversion is shown to be a function of soil strength, coefficient of earth pressure at rest, bedrock depth, and the horizontal position of the foundation relative to the outcropping fault rupture. For the second phenomenon （Step 4）, a heuristic approach is proposed, which ＂scans＂ through possible equilibrium positions to detect the one that best satisfies force and moment equilibrium. Thus, we account for the strong geometric nonlinearities that govern this interaction, such as uplifting and second order （P-△） effects. Comparisons with centrifuge-validated finite element analyses demonstrate the efficacy of the method. Its simplicity makes possible its utilization for preliminary design.展开更多
AIM: To investigate the therapeutic effects of Guiyuanfang and bone marrow stem cells (BMSCs) on rats with liver fibrosis.METHODS: Liver fibrosis model was induced by carbon tetrachloride, ethanol, high lipid and asse...AIM: To investigate the therapeutic effects of Guiyuanfang and bone marrow stem cells (BMSCs) on rats with liver fibrosis.METHODS: Liver fibrosis model was induced by carbon tetrachloride, ethanol, high lipid and assessed biochemically and histologically. Liver function and hydroxyproline contents of liver tissue were determined.Serum hyaluronic acid (HA) level and procollagen Ⅲ level were performed by radioimmunoassay. The VG staining was used to evaluate the collagen deposit in the liver.Immunohistochemical SABC methods were used to detect transplanted BMSCs and expression of urokinase plasminogen activator (uPA).RESULTS: Serum transaminase level and liver fibrosis in rats were markedly reduced by Guiyuanfang and BMSCs. HA level and procollagen Ⅲ level were also reduced obviously,compared to model rats (HA: 47.18±10.97 ng/mL,48.96±14.79 ng/mL; PCⅢ: 22.48±5.46 ng/mL, 26.90±3.35ng/mL; P＜0.05).Hydroxyproline contents of liver tissue in both BMSCs group and Guiyuanfang group were far lower than that of model group (1 227.2±43.1 μg/g liver tissue, 1390.8±156.3 μg/g liver tissue; P＜0.01). After treatment fibrosis scores were also reduced. Both Guiyuanfang and BMSCs could increase the expression of uPA. The transplanted BMSCs could engraft, survive, and proliferate in the liver.CONCLUSION: Guiyuanfang protects against liver fibrosis.Transplanted BMSCs may engraft, survive, and proliferate in the fibrosis livers indefinitely. Guiyuanfang may synergize with BMSCs to improve recovery from liver fibrosis.展开更多
基金funded by Hung Yen University of Technology and Education under grand number UTEHY.L.2025.62.
文摘Unmanned Aerial Vehicles(UAVs)have become integral components in smart city infrastructures,supporting applications such as emergency response,surveillance,and data collection.However,the high mobility and dynamic topology of Flying Ad Hoc Networks(FANETs)present significant challenges for maintaining reliable,low-latency communication.Conventional geographic routing protocols often struggle in situations where link quality varies and mobility patterns are unpredictable.To overcome these limitations,this paper proposes an improved routing protocol based on reinforcement learning.This new approach integrates Q-learning with mechanisms that are both link-aware and mobility-aware.The proposed method optimizes the selection of relay nodes by using an adaptive reward function that takes into account energy consumption,delay,and link quality.Additionally,a Kalman filter is integrated to predict UAV mobility,improving the stability of communication links under dynamic network conditions.Simulation experiments were conducted using realistic scenarios,varying the number of UAVs to assess scalability.An analysis was conducted on key performance metrics,including the packet delivery ratio,end-to-end delay,and total energy consumption.The results demonstrate that the proposed approach significantly improves the packet delivery ratio by 12%–15%and reduces delay by up to 25.5%when compared to conventional GEO and QGEO protocols.However,this improvement comes at the cost of higher energy consumption due to additional computations and control overhead.Despite this trade-off,the proposed solution ensures reliable and efficient communication,making it well-suited for large-scale UAV networks operating in complex urban environments.
文摘Hydroelectric power production from Garafiri dam and rainfall are essential elements with the observation of hydroelectric power production in West African power system,particularly in Guinea.This article focuses on the study and the influence of climate variability on hydroelectric power production at Garafiri dam over 16-year period(2008-2023).The aim of this work is to show the correlation between rainfall anomalies and hydroelectric power production at Garafiri dam.The method used consists of calculating precipitation anomalies at Garafiri site and those for the production of hydroelectric power from Garafiri dam over the study period.This approach led us to calculate the anomalies,leading to the study on climatic variability,in order to establish correlation between rainfall and hydroelectric power dam’s production.The trend with the correlation found made it possible to carry out a significance test between these two variables.These results clearly show that rainfall in Garafiri site increases hydroelectric power production and vice versa,which explains the interdependence between these two parameters,i.e.climatic variability and hydroelectric power production.
文摘The association between Vitamin D and IBS has attracted growing interest because of vitamin D’s involvement in immune system function and reduction of inflammation. IBS, a prevalent gastrointestinal condition marked by symptoms such as stomach pain, bloating, and changed bowel habits, implies that sufficient levels of Vitamin D may impact the symptomatology and quality of life associated with IBS. This review aimed to unveil current insights on vitamin D intake, status and symptoms of irritable bowel syndrome. A search was conducted on Embase, Scopus, Medline, and Cochrane Library, as well as a reference list of relevant studies. This paper also examined the current therapeutic practices for using vitamin D in the management of IBS. Although several studies demonstrate a positive association between vitamin D administration and the alleviation of IBS symptoms, the data is not yet definitive. Moreover, the review emphasised the necessity for additional rigorous clinical studies to determine a definitive therapeutic function of vitamin D in IBS based on the literature. The role of vitamin D in the modulation of gut health, particularly in IBS, has garnered significant attention due to its potential impact on both inflammation and the integrity of the gut barrier. Vitamin D, acting as a hormone precursor, is recognised for its crucial involvement in maintaining calcium balance and promoting bone health.
文摘Changdao Island,a hidden gem in east China’s Shandong Province,features breathtaking nature.As the sun cuddles the horizon,the island’s azure sky provides a flawless backdrop to an exquisite panorama.Jagged cliffs carved by centuries of endless waves stand guard along the shoreline,their rocky silhouettes seemingly frozen in time,summoning ancient majesty.Against this dramatic backdrop,flocks of seagulls take flight,their ivory wings catching the golden hues of the sun,creating an enchanting ballet in the sky.The air is filled with the gentle cries of these graceful birds,enhancing the island’s serenity.This harmonious blend of nature’s elements,from the sapphire sea to the towering cliffs and the mesmerizing flight of seagulls,makes Changdao Island an artistic masterpiece painted by the hand of mother nature herself.
文摘The confidentiality of pseudonymous authentication and secure data transmission is essential for the protection of information and mitigating risks posed by compromised vehicles.The Internet of Vehicles has meaningful applications,enabling connected and autonomous vehicles to interact with infrastructure,sensors,computing nodes,humans,and fellow vehicles.Vehicular hoc networks play an essential role in enhancing driving efficiency and safety by reducing traffic congestion while adhering to cryptographic security standards.This paper introduces a privacy-preserving Vehicle-to-Infrastructure authentication,utilizing encryption and the Moore curve.The proposed approach enables a vehicle to deduce the planned itinerary of Roadside Units(RSUs)before embarking on a journey.Crucially,the Certification Authority remains unaware of the specific route design,ensuring privacy.The method involves transforming all Roadside Units(RSUs)in a region into a vector,allowing for instant authentication of a vehicle’s route using RSU information.Real-world performance evaluations affirm the effectiveness of the proposed model.
基金National Natural Science Foundation of China Under Grant No.50139010
文摘Based on research studies currently being carried out at Dalian University of Technology, some important aspects for the earthquake safety assessmcnt of concrete dams are reviewed and discussed. First, the rate-dependent behavior of concrcte subjected to earthquake loading is examined, emphasizing the properties of concrete under cyclic and biaxial loading conditions. Second, a modified four-parameter Hsieh-Ting-Chen viscoplastic consistency model is developed to simulate the rate-dependent behavior of concrete. The earthquake response of a 278m high arch dam is analyzed, and the results show that the strain-rate effects become noticeable in the inelastic range, Third, a more accurate non-smooth Newton algorithm for the solution of three-dimensional frictional contact problems is developed to study the joint opening effects of arch dams during strong earthquakes. Such effects on two nearly 300m high arch dams have been studied. It was found that the canyon shape has great influence on the magnitude and distribution of the joint opening along the dam axis. Fourth, the scaled boundary finite element method presented by Song and Wolf is employed to study the dam-reservoir-foundation interaction effects of concrete dams. Particular emphases were placed on the variation of foundation stiffness and the anisotropic behavior of the foundation material on the dynamic response of concrete dams. Finally, nonlinear modeling of concrete to study the damage evolution of concrete dams during strong earthquakes is discussed. An elastic-damage mechanics approach for damage prediction of concrete gravity dams is described as an example. These findings are helpful in understanding the dynamic behavior of concrete dams and promoting the improvement of seismic safety assessment methods.
文摘Improving vehicle fuel consumption,performance and aerodynamic efficiency by drag reduction especially in heavy vehicles is one of the indispensable issues of automotive industry.In this work,the effects of adding append devices like deflector and cab vane corner on heavy commercial vehicle drag reduction were investigated.For this purpose,the vehicle body structure was modeled with various supplementary parts at the first stage.Then,computational fluid dynamic(CFD) analysis was utilized for each case to enhance the optimal aerodynamic structure at different longitudinal speeds for heavy commercial vehicles.The results show that the most effective supplementary part is deflector,and by adding this part,the drag coefficient is decreased considerably at an optimum angle.By adding two cab vane corners at both frontal edges of cab,a significant drag reduction is noticed.Back vanes and base flaps are simple plates which can be added at the top and side end of container and at the bottom with specific angle respectively to direct the flow and prevent the turbulence.Through the analysis of airflow and pressure distribution,the results reveal that the cab vane reduces fuel consumption and drag coefficient by up to 20 % receptively using proper deflector angle.Finally,by adding all supplementary parts at their optimized positions,41% drag reduction is obtained compared to the simple model.
文摘Diagnostic imaging plays a key role in the diagnosis and management of inflammatory bowel disease(IBD). However due to the relapsing nature of IBD, there is growing concern that IBD patients may be exposed to potentially harmful cumulative levels of ionising radiation in their lifetime, increasing malignant potential in a population already at risk. In this review we explore the proportion of IBD patients exposed to high cumulative radiation doses, the risk factors associated with higher radiation exposures, and we compare conventional diagnostic imaging with newer radiation-free imaging techniques used in the evaluation of patients with IBD. While computed tomography(CT) performs well as an imaging modality for IBD, the effective radiation dose is considerably higher than other abdominal imaging modalities. It is increasingly recognised that CT imaging remains responsible for the majority of diagnostic medical radiation to which IBD patients are exposed. Magnetic resonance imaging(MRI) and small intestine contrast enhanced ultrasonography(SICUS) have now emerged as suitable radiation-free alternatives to CT imaging, with comparable diagnostic accuracy. The routine use of MRI and SICUS for the clinical evaluation of patients with known or suspected small bowel Crohn's disease is to be encouraged wherever possible. More provision is needed for out-of-hours radiation-free imaging modalities to reduce the need for CT.
基金EU Fifth Framework Program: Environment, Energy and Sustainable Development Research and Technological Development Activity of Generic Nature: The Fight Against Natural and Technological Hazards, Research Project QUAKER Under Contract No. EVG1–CT–2002–00064
文摘To gain insight into the inelastic behavior of piles, the response of a vertical pile embedded in dry sand and subjected to cyclic lateral loading was studied experimentally in centrifuge tests conducted in Laboratoire Central des Ponts et Chaussees. Three types of cyclic loading were applied, two asymmetric and one symmetric with respect to the unloaded pile. An approximately square-root variation of soil stiffness with depth was obtained from indirect in-flight density measurements, laboratory tests on reconstituted samples, and well-established empirical correlations. The tests were simulated using a cyclic nonlinear Winkler spring model, which describes the full range of inelastic phenomena, including separation and re-attachment of the pile from and to the soil. The model consists of three mathematical expressions capable of reproducing a wide variety of monotonic and cyclic experimentalp-y curves. The physical meaning of key model parameters is graphically explained and related to soil behavior. Comparisons with the centrifuge test results demonstrate the general validity of the model and its ability to capture several features of pile-soil interaction, including： soil plastification at an early stage of loading, ＂pinching＂ behavior due to the formation of a relaxation zone around the upper part of the pile, and stiffness and strength changes due to cyclic loading. A comparison of the p-y curves derived from the test results and the proposed model, as well as those from the classical curves of Reese et al. （1974） for sand, is also presented.
文摘Gastric cancer poses a significant public health problem, especially in the Far East, due to its high incidence in these areas. Surgical treatment and guidelines have been markedly different in the West, but nowadays this debate is apparently coming to an end. Laparoscopic surgery has been employed in the surgical treatment of gastric cancer for two decades now, but with controversies about the extent of resection and lymphadenectomy. Despite these difficulties, the apparent advantages of the laparoscopic approach helped its implementation in early stage and distal gastric cancer, with an increase on the uptake for distal gastrectomy for more advanced disease and total gastrectomy. Nevertheless, there is no conclusive evidence about the laparoscopic approach yet. In this review article we present and analyse the current status of laparoscopic surgery in the treatment of gastric cancer.
基金National Natural Science Foundation of China for Innovative Research Groups Under Grant No. 50321803 National Natural Science Foundation of China for Young Scholars Under Grant No. 10402030
文摘A new approach to evaluate the extreme value distribution （EVD） of the response and reliability of general multi-DOF nonlinear stochastic structures is proposed. The approach is based on the recently developed probability density evolution method, which enables the instantaneous probability density functions of the stochastic responses to be captured. In the proposed method, a virtual stochastic process is first constructed to satisfy the condition that the extreme value of the response equals the value of the constructed process at a certain instant of time. The probability density evolution method is then applied to evaluate the instantaneous probability density function of the response, yielding the EVD. The reliability is therefore available through a simple integration over the safe domain. A numerical algorithm is developed using the Number Theoretical Method to select the discretized representative points. Further, a hyper-ball is imposed to sieve the points from the preceding point set in the hypercube. In the numerical examples, the EVD of random variables is evaluated and compared with the analytical solution. A frame structure is analyzed to capture the EVD of the response and the dynamic reliability. The investigations indicate that the proposed approach provides reasonable accuracy and efficiency.
基金U.S. Federal Highway Administration Under Grant No. DTFH61-98-C-00094U.S. National Science Foundation Under Grant No. EEC-9701471
文摘An analytical method to study the seismic response of a bridge pier supported on a rigid caisson foundation embedded in a deep soil stratum underlain by a homogeneous half space is developed. The method reproduces the kinematic and inertial responses, using translational and rotational distributed Winkler springs and dashpots to simulate the soil-caisson interaction. Closed-form solutions are given in the frequency domain for vertical harmonic S-wave excitation. Comparison with results from finite element （FE） analysis and other available solutions demonstrates the reliability of the model. Results from parametric studies are given for the kinematic and inertial responses. The modification of the fundamental period and damping ratio of the bridge due to soil-structure interaction is graphically illustrated.
文摘AIM To compare outcomes in patients undergoing rectal resection by robotic total meso-rectal excision(RTME) vs laparoscopic total meso-rectal excision(LTME).METHODS Standard medical electronic databases such as Pub-Med, MEDLINE, EMBASE and Scopus were searched to find relevant articles. The data retrieved from all types of included published comparative trials in pati-ents undergoing RTME vs LTME was analysed using the principles of meta-analysis. The operative, post-operative and oncological outcomes were evaluated to assess the effectiveness of both techniques of TME. The summated outcome of continuous variables was expressed as standardized mean difference(SMD) and dichotomous data was presented in odds ratio(OR).RESULTS One RCT(ROLARR trial) and 27 other comparative studies reporting the non-oncological and oncological outcomes following RTME vs LTME were included in this review. In the random effects model analysis using the statistical software Review Manager 5.3, the RTME was associated with longer operation time(SMD, 0.46; 95%CI: 0.25, 0.67; z = 4.33; P = 0.0001), early passage of first flatus(P = 0.002), lower risk of conversion(P = 0.00001) and shorter hospitalization(P = 0.01). The statistical equivalence was seen between RTME and LTME for non-oncological variables like blo-od loss, morbidity, mortality and re-operation risk. The oncological variables such as recurrence(P = 0.96), number of harvested nodes(P = 0.49) and positive circumferential resection margin risk(P = 0.53) were also comparable in both groups. The length of distal resection margins was similar in both groups. CONCLUSION RTME is feasible and oncologically safe but failed to demonstrate any superiority over LTME for many sur-gical outcomes except early passage of flatus, lower risk of conversion and shorter hospitalization.
文摘Radiotherapy(RT) after tumorectomy in early breast cancer patients is an established treatment modality which conventionally takes 6-7 wk to complete.Shorter RT schedules have been tested in large multicentre randomized trials and have shown equivalent results to that of standard RT(50 Gy in 25 fractions) in terms of local tumor control,patient survival and late post-radiation effects.Some of those trials have now completed 10 years of follow-up with encouraging results for treatments of 3-4 wk and a total RT dose to the breast of 40-42.5 Gy with or without boost.A reduction of 50% in treatment time makes those RT schedules attractive for both patients and health care providers and would have a significant impact on daily RT practice around the world,as it would accelerate patient turnover and save health care resources.However,in hypofractionated RT,a higher(than the conventional 1.8-2 Gy) dose per fraction is given and should be managed with caution as it could result in a higher rate of late postradiation effects in breast,heart,lungs and the brachial plexus.It is therefore advisable that both possible dose inhomogeneity and normal tissue protection should be taken into account and the appropriate technology such as three-dimensional/intensity modulated radiation therapy employed in clinical practice,when hypofractionation is used.
文摘Massive segmental bone loss due to chronic osteomyelitis represents a considerable challenge to orthopedic surgeons and is a limb threatening condition.The only option available in such a clinical situation is segment transport using the Ilizarov technique of distraction osteogenesis;yet the most common problem in cases of bone transport with the Ilizarov technique in massive bone loss,is the long duration of the fixator.In addition to autologous bone grafting,several mechanical,biologic,and external physical treatment modalities may be employed to promote bone formation and maturation during segment transport in osteomyelitis patients.Mechanical approaches include compressive loading of the distraction regenerate,increased frequency of small increments of distraction,and compression-distraction.Intramedullary nailing and hemicorticotomy can reduce the time in external fixation;however,these techniques are associated with technical difficulties and complications.Exogenous application of low-intensity pulsed ultrasound or pulsed electromagnetic fields may shorten the duration of external fixation.Other promising modalities include diphosphonates,physician-directed use(off-label use)of bone morphogenetic proteins,and local injection of bone marrow aspirate and platelet gel at the osteotomy site.Well-designed clinical studies are needed to establish safe and effective guidelines for various modalities to enhance new bone formation during distraction osteogenesis after segment transfer.
基金OSE (the Greek Railway Organization)the EU Fifth Framework Programme Under Grant No. EVG1-CT-2002-00064
文摘This is the second paper of two, which describe the results of an integrated research effort to develop a four-step simplified approach for design of raft foundations against dip-slip （normal and thrust） fault rupture. The first two steps dealing with fault rupture propagation in the free-field were presented in the companion paper. This paper develops an approximate analytical method to analyze soil-foundation-structure interaction （SFSI）, involving two additional phenomena： （i） fault rupture diversion （Step 3）; and （ii） modification of the vertical displacement profile （Step 4）. For the first phenomenon （Step 3）, an approximate energy-based approach is developed to estimate the diversion of a fault rupture due to presence of a raft foundation. The normalized critical load for complete diversion is shown to be a function of soil strength, coefficient of earth pressure at rest, bedrock depth, and the horizontal position of the foundation relative to the outcropping fault rupture. For the second phenomenon （Step 4）, a heuristic approach is proposed, which ＂scans＂ through possible equilibrium positions to detect the one that best satisfies force and moment equilibrium. Thus, we account for the strong geometric nonlinearities that govern this interaction, such as uplifting and second order （P-△） effects. Comparisons with centrifuge-validated finite element analyses demonstrate the efficacy of the method. Its simplicity makes possible its utilization for preliminary design.
基金Supported by the National Natural Science Foundation of China, No. 30271663
文摘AIM: To investigate the therapeutic effects of Guiyuanfang and bone marrow stem cells (BMSCs) on rats with liver fibrosis.METHODS: Liver fibrosis model was induced by carbon tetrachloride, ethanol, high lipid and assessed biochemically and histologically. Liver function and hydroxyproline contents of liver tissue were determined.Serum hyaluronic acid (HA) level and procollagen Ⅲ level were performed by radioimmunoassay. The VG staining was used to evaluate the collagen deposit in the liver.Immunohistochemical SABC methods were used to detect transplanted BMSCs and expression of urokinase plasminogen activator (uPA).RESULTS: Serum transaminase level and liver fibrosis in rats were markedly reduced by Guiyuanfang and BMSCs. HA level and procollagen Ⅲ level were also reduced obviously,compared to model rats (HA: 47.18±10.97 ng/mL,48.96±14.79 ng/mL; PCⅢ: 22.48±5.46 ng/mL, 26.90±3.35ng/mL; P＜0.05).Hydroxyproline contents of liver tissue in both BMSCs group and Guiyuanfang group were far lower than that of model group (1 227.2±43.1 μg/g liver tissue, 1390.8±156.3 μg/g liver tissue; P＜0.01). After treatment fibrosis scores were also reduced. Both Guiyuanfang and BMSCs could increase the expression of uPA. The transplanted BMSCs could engraft, survive, and proliferate in the liver.CONCLUSION: Guiyuanfang protects against liver fibrosis.Transplanted BMSCs may engraft, survive, and proliferate in the fibrosis livers indefinitely. Guiyuanfang may synergize with BMSCs to improve recovery from liver fibrosis.
