Using the low-resolution (T31, equivalent to 3.75°× 3.75°) version of the Community Earth System Model (CESM) from the National Center for Atmospheric Research (NCAR), a global climate simulation ...Using the low-resolution (T31, equivalent to 3.75°× 3.75°) version of the Community Earth System Model (CESM) from the National Center for Atmospheric Research (NCAR), a global climate simulation was carried out with fixed external forcing factors (1850 Common Era. (C.E.) conditions) for the past 2000 years. Based on the simulated results, spatio-temporal structures of surface air temperature, precipitation and internal variability, such as the E1 Nifio-Southem Oscillation (ENSO), the Atlantic Multi-decadal Oscilla- tion (AMO), the Pacific Decadal Oscillation (PDO), and the North Atlantic Oscillation (NAO), were compared with reanalysis datasets to evaluate the model performance. The results are as follows: 1) CESM showed a good performance in the long-term simulation and no significant climate drift over the past 2000 years; 2) climatological patterns of global and regional climate changes simulated by the CESM were reasonable compared with the reanalysis datasets; and 3) the CESM simulated internal natural variability of the climate system performs very well. The model not only reproduced the periodicity of ENSO, AMO and PDO events but also the 3-8 years vari- ability of the ENSO. The spatial distribution of the CESM-simulated NAO was also similar to the observed. However, because of weaker total irradiation and greenhouse gas concentration forcing in the simulation than the present, the model performances had some differences from the observations. Generally, the CESM showed a good performance in simulating the global climate and internal natu- ral variability of the climate system. This paves the way for other forced climate simulations for the past 2000 years by using the CESM.展开更多
In order to solve the difficult conditions of soft rock,water-trickling and hard-maintain of main air-return roadway in Tarangaole Colliery,high pretensioned stress and intensive bolt-shotcrete support program was des...In order to solve the difficult conditions of soft rock,water-trickling and hard-maintain of main air-return roadway in Tarangaole Colliery,high pretensioned stress and intensive bolt-shotcrete support program was designed and mechanical property of shotcrete layer was specially monitored through utilizing a type of concrete stress meter with oscillating chord after the program was carried out.It was indicated that,due to rock pressure and support resistance,the interior of shotcrete layer would emerge diverse stresses in axial,radial and tangential directions.With time passing internal stresses in three directions,whose average values were-0.061,0.043 and 0.517 MPa respectively,fluctuated first and then tended to stability slowly.The axial and radial stresses were relatively smaller than tangential stress which was 11,12 times the two formers respectively.Along the section of roadway,axial and tangential stresses distributed symmetrically and increased gradually from the top of arch to the waist of wall,but reduced at the foot of wall.Radial stresses reduced from the top of arch to the waist of arch first,and then increased in the waist of wall.Axial stresses were tensile substantially,except for stresses in arch vault tending to compressive,but all the radial stresses were compressive.Nevertheless,tangential stresses in the wall were compressive and tangential stresses in the arch were tensile.During the period of roadway excavating,the stress of shotcrete layer was less than its ultimate bearing capacity,with no significant stress concentration.At the end of this article,some suggests are given to shotcrete support design.展开更多
There is less research on vertical sculptured grinding technology. Especially in high vertical surface grinding process with the cup abrasive wheel, the thermal damage is prone to happen and undermine the grinding sur...There is less research on vertical sculptured grinding technology. Especially in high vertical surface grinding process with the cup abrasive wheel, the thermal damage is prone to happen and undermine the grinding surface integrity. This problem limits to improve the grinding efficiency and the grinding ratio greatly. Through the analysis of vertical surface grinding process and features in depth, this paper revealed the inherent mechanism of higher grinding temperature in the process of vertical sculptured grinding using the cup wheel. Based on the previous research achievements, the grinding experiments on TC4 (Ti-6A1-4V) and GH4169 are carried out utilizing the self-inhaling internal cooling wheel. The experimental results show that the self-inhaling internal cooling wheel can efficiently reduce the grinding surface temperature. Moreover, the inherent mechanism of reducing the grinding temperature using the internal cooling method is revealed. Meanwhile, under the same grinding conditions, the grinding ratio during the experiments on GH4169 using self-inhaling internal cooling method is about 3 times as high as using conventional external cooling method. And the grinding forces can be reduced by about 20%. This research revealed the inherent mechanism of higher grinding temperature in the process of vertical sculptured grinding using the cup wheel, which provides theoretical basis for the design and application of self-inhaling internal cooling wheel. At the same time, an efficient and non-invasive surface grinding method of TC4 and GH4169 is presented.展开更多
In this paper, iterative learning control (ILC) design is studied for an iteration-varying tracking problem in which reference trajectories are generated by high-order internal models (HOLM). An HOlM formulated as...In this paper, iterative learning control (ILC) design is studied for an iteration-varying tracking problem in which reference trajectories are generated by high-order internal models (HOLM). An HOlM formulated as a polynomial operator between consecutive iterations describes the changes of desired trajectories in the iteration domain and makes the iterative learning problem become iteration varying. The classical ILC for tracking iteration-invariant reference trajectories, on the other hand, is a special case of HOlM where the polynomial renders to a unity coefficient or a special first-order internal model. By inserting the HOlM into P-type ILC, the tracking performance along the iteration axis is investigated for a class of continuous-time nonlinear systems. Time-weighted norm method is utilized to guarantee validity of proposed algorithm in a sense of data-driven control.展开更多
Objective To evaluate the efficacy of simultaneous anterior and posterior hemivertebra resection in the treatment of congenital kyphoscoliosis caused by fully-segmented hemivertebra. Methods Twenty-one consecutive ca...Objective To evaluate the efficacy of simultaneous anterior and posterior hemivertebra resection in the treatment of congenital kyphoscoliosis caused by fully-segmented hemivertebra. Methods Twenty-one consecutive cases with congenital kyphoscoliosis, which were 8 males and 13 females, underwent one-stage operation of anterior hemivertebra resection and posterior instrumentation. All of the hemivertebra were fully-segmented. The average age at surgery was 11.4 (range, 1.5-16) years old. Results The average follow-up was 23 (range, 6-50) months. The average Cobb's angle of the coronal curve was 51.4° (30°-120°) before surgery, 16.9° (0°-54°) after surgery, and 19.5° at latest follow-up. The angle of segmental kyphosis was 37.1° (0°-95°) before surgery and 16.1° (0°-48°) after surgery, and 18.2° at latest follow-up. Apical translation was improved from 4.7 cm to 1.9 cm. The average fusion segments were 4.8 (range, 2-10) segments. Complication included pressure sore in one case, pedicle cutting by pedicle screw in one case and elongation of the curve in one case. There was no obvious pseudarthrosis, decompensation, and kyohosis deformity aggravation at latest follow-up. Conclusion One-stage hemivortebra resection has a good result in the surgical treatment of congenital kyphoscoliosis caused by fully-segmented hemivertebra, and may shorten fusion levels if performed at an earlier age.展开更多
Due to low carrying capacity and short life of current ring reducer,we proposed a new planetary gearing with internal gear ring,which consisted of two stages.One was an involute planetary drive and the other was an N-...Due to low carrying capacity and short life of current ring reducer,we proposed a new planetary gearing with internal gear ring,which consisted of two stages.One was an involute planetary drive and the other was an N-type planetary drive with small teeth difference.The kinematic calculation was conducted based on the analysis of structural composition and working principle.Formulas of backlash calculation for the new planetary gearing were derived by using probabilistic theory and the analytical model was created at the same time.Then,main factors that affect the systematic backlash were introduced and the effects of manufacture error,misaligments and roller bearing parameters on the distribution of backlash were presented.The influence of gear backlash on systematic return difference was performed based on the backlash mathematic model proposed.The results show that the backlash is a little large,of which the backlash of bearing takes a greater part than two gearing stages.So we presented some practical methods to reduce the systematic backlash.展开更多
Objective To evaluate the operative technique and preliminary results of video-assisted thoracoscopic anterior correction and fusion of scoliosis. Methods Eleven cases underwent thoracoscopic anterior correction and f...Objective To evaluate the operative technique and preliminary results of video-assisted thoracoscopic anterior correction and fusion of scoliosis. Methods Eleven cases underwent thoracoscopic anterior correction and fusion of scoliosis from March 2003 to April 2005 in our hospital were reviewed. They were all females with an average age of 13.1 years old. Of which, 9 cases were idiopathic scoliosis, 1 case was congenital scoliosis, and 1 case was Marian syndrome scoliosis. The coronal Cobb angle and apical vertebral translation before and after surgery as well as at final follow-up were measured. The operation time, blood loss during operation, and peri-operative complications were recorded. The mean operation time was 6. 4 hours, mean instrumented vertebrae were 6.4 segments, and mean blood loss during operation was 364 mU The coronal Cobb angles of the thoracic curve before and after surgery were 45.5° and 15.4° respectively, with an average correction rate of 65.4%. The lumbar curve was corrected from 28.4° to 11.8° , with an average simultaneous correction rate of 57.2%. All of the patients were followed up regularly with an average time of 21.4 months. At the final foUow-up, the coronal Cobb angles of the thoracic and lumbar curves were 19.0° and 20. 1° , with a 3.6° and 8. 3° loss of correction, respectively. The apical vertebral translation was improved from 32. 3 mm to 10.5 mm for the thoracic curve, and from 13.1 mm to 8.2 mm for the lumbar curve. There were 6 cases with peri-opemtive complications, including 1 case of thoracic effusion, 1 case of chylothomx, 1 case of locking plug loosing, 2 cases of aggravation of the unfused lumbar curve ( 1 case also with thoracolumbar kyphosis), and 1 case with a screw tip causing a contour deformity of the aorta. And 4 of them underwent revision surgery.Conclusions Video-assisted thoracoscopic anterior correction and fusion of scoliosis has good correction capability, less intraoperative bleeding, and favorable cosmetic effect for mild and moderate thoracic scoliosis, but with higher rates of cor- rection loss of the lumbar curve and peri-operative complications. A surgeon should be cautious to perform this technique.展开更多
In this paper a system combining a diesel reformer using catalytic partial oxidation (CPOX) with the Solid Oxide Fuel Cell (SOFC) for Auxiliary Power Unit (APU) applications is modeled with respect to the coolin...In this paper a system combining a diesel reformer using catalytic partial oxidation (CPOX) with the Solid Oxide Fuel Cell (SOFC) for Auxiliary Power Unit (APU) applications is modeled with respect to the cooling effect provided by internal reforming of methane in anode gas channel. A model mixture consisting of 80% n-hexadecane and 20%..!-methylnaphthalin is used to simulate the commercial diesel. The modelling consists of several steps. First, equilibrium gas composition at the exit of CPOX reformer is modelled in terms oxygen to car- bon (O/C) ratio, fuel utilization ratio and anode gas recirculation. Second, product composition, especially methane content, is determined for the me.th.an, ation process at the operating temperatures ra:ng!ng from 500 ℃to 520 ℃.Finally, the cooling power provided by internal reforming of methane in SOFC fuel channel is calculated for two concepts to increase the methane content of the diesel reformate. The results show that the first concept, operating the diesel reformer at low O/C ratio and/or, recirculation rat!o, is not realizable due to high probability of coke formation, whereas the second concept, combining a methanation process with CPOX, can provide a significant cool- ing effect in addition to the conventional c?oling concept which needs higher levels of excess air.展开更多
The study was motivated by the fact that explosion inside the subway structure may not only cause direct life loss,but also damage the subway structure and lead to further loss of lives and properties.The propagation ...The study was motivated by the fact that explosion inside the subway structure may not only cause direct life loss,but also damage the subway structure and lead to further loss of lives and properties.The propagation law of explosion wave in the subway station was analyzed and a simplified model of overpressure in the subway station was also proposed.Whereafter,the improved dynamic cam-clay model of soil and the concrete damaged plasticity constitutive model were used for the dynamic analysis of the subway station.Meanwhile,the influences of soil stiffness and burial depth on the dynamic response of the subway station were looked into.The results show that the multi-peak overpressure in the subway station does not appear,and large stresses concentrate on the central column and the floor slab of the subway station,so some special reinforcement measures should be taken in these parts.The effect of soil stiffness and burial depth on the stress of the central column is little;however,the effect on the stress of the station side wall is relatively obvious.展开更多
Many ecosystems extend across national or political boundaries. The consistent and effective protection of these ecosystems in transboundary areas(ETAs) is an important global research focus. Previous research on the ...Many ecosystems extend across national or political boundaries. The consistent and effective protection of these ecosystems in transboundary areas(ETAs) is an important global research focus. Previous research on the protection of such areas can be categorized into seven themes: 1) ecological conservation of a single ETA; 2) investigation of the effects of a single conservation measure on a specific ETA; 3) determination of species-level effects due to ETA conservation; 4) comparison of the same protection measures between different ETAs; 5) introduction of a single conservation measure to a specific ETA; 6) understanding the relationship between conservation and sustainable development; and 7) generalization across multiple ETA conservation cases. The protection of ETAs involves various considerations, including funding support, demand and will for collaboration, community and public participation, historical and cultural factors, political backgrounds, uniqueness of biological resources, formulation of laws and regulations, founding of specialized administrative departments, non-governmental organizations, and fairness. Here, we briefly explain the research themes and considerations related to ETA conservation. The most important finding is that most major research themes do not focus on the challenges of ETA conservation. We use two nature reserves located between China and North Korea as examples to identify specific ways to improve ETA conservation on Changbai Mountains. The efficiency of ETA administration still remains low. The study of ETA conservation should focus on concrete regional information and aim to improve existing measures through the accumulation of experience.展开更多
AIM:To assess the impact of macular surgery on the functional and anatomic outcomes of the patients in different grades of epiretinal membrane(ERM).METHODS:Seventy-one eyes of 71 patients who underwent 23-gauge tr...AIM:To assess the impact of macular surgery on the functional and anatomic outcomes of the patients in different grades of epiretinal membrane(ERM).METHODS:Seventy-one eyes of 71 patients who underwent 23-gauge transconjunctival sutureless pars plana vitrectomy for primary isolated ERM were evaluated in this study.RESULTS:There were 38 females(53.5%) and 33 males(46.5%).The average age of the patients was 68.1 y(range 42-89 y).Mean follow up period was 14 mo(range 6-26 mo).The cases were divided into two subgroups of cellophane maculopathy(CM) and macular pucker(MP).An improvement was observed in the postoperative best-corrected visual acuity(BCVA),as well as a decrement in central foveal thickness(CFT) in both groups(both of these being statistically significant;P=0.001).In comparison between two groups,it was found that there was a significant improvement on BCVA and CFT in CM group than MP group(P=0.01).Furthermore,the postoperative fundus findings regarding RPE alterations and macular edema were significantly higher in MP group when compared to the CM group(P=0.01).CONCLUSION:ERM and internal limiting membrane peeling surgery can lead to a significant reduction of CFT and visual improvements in idiopathic ERM.A long-term ERM persistence will cause unrecoverable retinal damage and visual loss.展开更多
Internal bond (IB) strength is one of the most important me- chanical properties that indicate particleboard quality. The aim of this study was to find a simple regression model that considers the most important par...Internal bond (IB) strength is one of the most important me- chanical properties that indicate particleboard quality. The aim of this study was to find a simple regression model that considers the most important parameters that can influence on IB strength. In this study, IB strength was predicted by three kinds of equations (linear, quadratic, and exponential) that were based on the percentage of adhesive (8%, 9.5%, and 11%), particle size (+5, -5 +8, -8 12, and -12 mesh), and density (0.65, 0.7, and 0.75 g/cm3). Our analysis of the results (using SHAZAM 9 software) showed that the exponential function best fitted the experi- mental data and predicted the IB strength with 18~,/0 error. In order de- crease the error percentage, the Buckingham Pi theorem was used to build regression models for predicting IB strength based on particle size,展开更多
The present study observed hemodynamic changes in 26 patients with cerebral arteriosclerosis using a cerebral circulation dynamics detector and transcranial Doppler. In patients with cerebral arteriosclerosis the bloo...The present study observed hemodynamic changes in 26 patients with cerebral arteriosclerosis using a cerebral circulation dynamics detector and transcranial Doppler. In patients with cerebral arteriosclerosis the blood supply and flow rate in the bilateral carotid arteries and the blood flow rate in the anterior cerebral and middle cerebral arteries were similar to normal controls, but the cerebral vascular resistance, critical pressure and pulsatility index were increased, and cerebral arterial elasticity and cerebral blood flow autoregulation were decreased. Compared with the lesioned hemisphere of patients with cerebral infarction, the total blood supply and blood flow rate of patients with cerebral arteriosclerosis were higher. Compared with normal subjects, patients with cerebral arteriosclerosis exhibited cognitive disturbances, mainly in short-term memory, attention, abstract capability, and spatial and executive dysfunction. Results showed that cerebral arteriosclerosis does not directly affect the blood supply of a cerebral hemisphere, but affects cognitive function. The increased cerebral vascular resistance and reduced autoregulation of cerebral blood vessels may be important hemodynamic mechanisms of arteriosclerosis-induced cerebral infarction.展开更多
Analyses of the effects of some parameters were performed to determine the admittance functions in a common two-compartment building with background porosity by the imposed excitation method.Variations of the magnific...Analyses of the effects of some parameters were performed to determine the admittance functions in a common two-compartment building with background porosity by the imposed excitation method.Variations of the magnification factors of fluctuating internal pressures were analyzed using 96 model cases under random fluctuating external pressure,and then corresponding design equations were fitted.The results show that the Helmholtz resonance peaks of the admittance functions in both compartments increase with increasing the area of windward or partition wall opening.With increasing the volume of the compartment with an external opening,the resonance peak in this compartment at the higher Helmholtz frequency significantly decreases,at the same time,the resonance peak in the other compartment at the lower Helmholtz frequency also decreases.With increasing the volume of the compartment with background porosity,both resonance peaks in this compartment at the lower and higher Helmholtz frequencies decrease,meanwhile,the resonance peak at the lower Helmholtz frequency for the other compartment also decreases,whereas the resonance peak at the higher Helmholtz frequency increases.Both resonance peaks of the admittance functions in the two compartments decrease with increasing the amplitude of fluctuating external pressure coefficients or reference wind speed.展开更多
Based on a nonhydrostatic numerical ocean model developed by one of the authors, the interaction of an intemal solitary wave with a step-type topography was investigated. Over the step topography, the flow pattern cou...Based on a nonhydrostatic numerical ocean model developed by one of the authors, the interaction of an intemal solitary wave with a step-type topography was investigated. Over the step topography, the flow pattern could be classified into three categories: 1) the propagation and spatial structure of the internal solitary wave was little influenced by the bottom topography, 2) the internal solitary wave was significantly distorted by the blocking effect of the topography without the occurrence of wave breaking and 3) the internal solitary wave was broken as it encountered and passed over the bottom topography. A detailed description of the processes leading to wave breaking is given in this paper together with energy budget analysis. The results revealed that the maximum of the energy dissipation rate is no more than 40%, which is consistent with available experimental data.展开更多
In this digital era, we have witness the exciting convergence of content, technology, and global collaboration in the development of digital libraries. The mode of universal access for information seeking and knowledg...In this digital era, we have witness the exciting convergence of content, technology, and global collaboration in the development of digital libraries. The mode of universal access for information seeking and knowledge acquisition differs greatly fi'om the traditional ways. From the information resources point of views, the old model of“owning” a collection has given way to “sharing,” and the new emphases have shifted fi'om possessing large “physical libraries” to “virtual libraries” digitally distributed all over the world. “Universal access” has taken on a very different meaning when one has the ability to share invaluable resources through the use of cutting edge technologies. The author has experienced much of these transformations through her own R&D activities-from the creation of interactive videodisc and multimedia CD on the First Emperor of China's terracotta warriors and horses in the 1980s and 1990s to leading a current international digital library project, Global Memory Net (GMNet), supported by the US National Science Foundation. In presenting her vision for linking world digital resources together for universal access, she will share with the audience the latest development of Global Memory Net.展开更多
A 55-year-old man was admitted for transcatheter closure because of pulmonary arteriovenous fistula by magnetic resonance angiography (MRA). He had a history of occasional chest pain more than one year. Angiography ...A 55-year-old man was admitted for transcatheter closure because of pulmonary arteriovenous fistula by magnetic resonance angiography (MRA). He had a history of occasional chest pain more than one year. Angiography didn't reveal significant stenosis at coronary artery. The patient was found a continuous grade 2/6 murmur over the left upper parastenal area one month ago. Chest MRA revealed a possible left superior pulmonary arteriovenous fistula. For diagnosis and localization of the fistula, aortography and selective angiography of the intemal mammary artery was performed and presented a left internal mammary artery-to-pulmonary artery fistula. The fistula was successfully closed using an 12 mm domestic vascular plug. Chest MRA showed that the fistula disappeared at two-month follow-up展开更多
In today's competitive environment the key element is the differentiation of business which will lead to success. Especially in international markets where there's much more intense competition, it is more important...In today's competitive environment the key element is the differentiation of business which will lead to success. Especially in international markets where there's much more intense competition, it is more important for businesses to enter with innovations that make a difference to their consumers. Innovation is also important for competitive export-oriented production in globalization. In global competition, innovation is the key factor for sustainable success. Increases in the efficiency, profitability of firms make it possible to enter new markets and extend present markets by obtaining advantage of competition. In order to determine accurate strategies, the connection between innovation and exports must be understood better. The aim of this study is to determine the innovation capability and export performance of Turkish export firms. Another aim is to examine the relationship between firm characteristics and innovation capability. Innovation capability of export firms is measured by INNOVSCALE which was developed by Vicente, Abrantes, and Teixeira (2015). Export performance is measured by APEV scale which was developed by Lages, Lages, and Lages (2005). The study uses data collected from 83 firms located in Kayseri. Results obtained by using SPSS indicate that there is a positive relationship between innovation capability and export performance. The results of the ANOVA analysis, innovation capability differ in terms of firm size and export earnings. Innovation capability does not differ in terms of sector, operating years, share of export earnings in the whole revenues, exporting periods, or internationalization levels.展开更多
We are living in a multi-polar world under the greater influence of one power. After the shutdown of the government in the US, it can be said that the sole power is about to be challenged. This paper hopes to establis...We are living in a multi-polar world under the greater influence of one power. After the shutdown of the government in the US, it can be said that the sole power is about to be challenged. This paper hopes to establish the fact that the future of the international system will continue to be multi-polar. Economic groupings like the Brazil, Russia, India, China, and South Africa (BRICS), Mexico, Indonesia, Singapore and Turkey (MIST) and others denote to this. These groupings may present an alternative to geographically locked but indispensible European Union. Despite the system being multi-polar, the United States dominates the international system. This paper deals with the BRICS countries that propose a bid for power in international relations. Will they have equidistant power form one another or will there be a hierarchy in between them? Can they take/make economic or political decisions? Is a geographically spread power structure more effective in controlling the balances between war and peace? Can they remain objective on trouble spots that may arise in Europe, the Middle East, the Balkans, Asia and the Americas? This paper hopes to achieve the goal of providing a framework for understanding a multi-polar approach to international relations based on the collaboration of BRICS countries. The first part will be the theoretical framework of the paper. The second part will be concerned with American supremacy in foreign relations and the need to question it. The third part will deal with emerging powers but since the most influential "power politics" are steered by China and Russia the main emphasis will be on them. The last part will come to the conclusion.展开更多
The strategy audit involves evaluation of the actual direction of a business and comparing that act to the direction required to succeed in a changing environment. A company's actual direction is the sum of what it s...The strategy audit involves evaluation of the actual direction of a business and comparing that act to the direction required to succeed in a changing environment. A company's actual direction is the sum of what it should and should not do, how well the organisation is internally aligned to support the strategy, and how viable the strategy is when compared to external market, competitor and financial realities. These categories, the internal assessment, and the external or environmental assessment, make up the major elements of a strategy audit. In this paper, it presents such a methodology which ensures an integrated process to evaluate the company's business strategy.展开更多
基金Under the auspices of National Basic Research Program of China(No.2010CB950102)Strategic and Special Frontier Project of Science and Technology of Chinese Academy of Sciences(No.XDA05080800)+3 种基金National Natural Science Foundation of China(No.41371209,41420104002)Special Research Fund for Doctoral Discipline of Higher Education Institutions(No.20133207110015)Natural Science Foundation of Jiangsu Higher Education Institutions(No.14KJA170002)Priority Academic Program Development of Jiangsu Higher Education Institutions(No.164320H101)
文摘Using the low-resolution (T31, equivalent to 3.75°× 3.75°) version of the Community Earth System Model (CESM) from the National Center for Atmospheric Research (NCAR), a global climate simulation was carried out with fixed external forcing factors (1850 Common Era. (C.E.) conditions) for the past 2000 years. Based on the simulated results, spatio-temporal structures of surface air temperature, precipitation and internal variability, such as the E1 Nifio-Southem Oscillation (ENSO), the Atlantic Multi-decadal Oscilla- tion (AMO), the Pacific Decadal Oscillation (PDO), and the North Atlantic Oscillation (NAO), were compared with reanalysis datasets to evaluate the model performance. The results are as follows: 1) CESM showed a good performance in the long-term simulation and no significant climate drift over the past 2000 years; 2) climatological patterns of global and regional climate changes simulated by the CESM were reasonable compared with the reanalysis datasets; and 3) the CESM simulated internal natural variability of the climate system performs very well. The model not only reproduced the periodicity of ENSO, AMO and PDO events but also the 3-8 years vari- ability of the ENSO. The spatial distribution of the CESM-simulated NAO was also similar to the observed. However, because of weaker total irradiation and greenhouse gas concentration forcing in the simulation than the present, the model performances had some differences from the observations. Generally, the CESM showed a good performance in simulating the global climate and internal natu- ral variability of the climate system. This paves the way for other forced climate simulations for the past 2000 years by using the CESM.
文摘In order to solve the difficult conditions of soft rock,water-trickling and hard-maintain of main air-return roadway in Tarangaole Colliery,high pretensioned stress and intensive bolt-shotcrete support program was designed and mechanical property of shotcrete layer was specially monitored through utilizing a type of concrete stress meter with oscillating chord after the program was carried out.It was indicated that,due to rock pressure and support resistance,the interior of shotcrete layer would emerge diverse stresses in axial,radial and tangential directions.With time passing internal stresses in three directions,whose average values were-0.061,0.043 and 0.517 MPa respectively,fluctuated first and then tended to stability slowly.The axial and radial stresses were relatively smaller than tangential stress which was 11,12 times the two formers respectively.Along the section of roadway,axial and tangential stresses distributed symmetrically and increased gradually from the top of arch to the waist of wall,but reduced at the foot of wall.Radial stresses reduced from the top of arch to the waist of arch first,and then increased in the waist of wall.Axial stresses were tensile substantially,except for stresses in arch vault tending to compressive,but all the radial stresses were compressive.Nevertheless,tangential stresses in the wall were compressive and tangential stresses in the arch were tensile.During the period of roadway excavating,the stress of shotcrete layer was less than its ultimate bearing capacity,with no significant stress concentration.At the end of this article,some suggests are given to shotcrete support design.
基金supported by National Natural Science Foundation of China(Grant No.51105024)
文摘There is less research on vertical sculptured grinding technology. Especially in high vertical surface grinding process with the cup abrasive wheel, the thermal damage is prone to happen and undermine the grinding surface integrity. This problem limits to improve the grinding efficiency and the grinding ratio greatly. Through the analysis of vertical surface grinding process and features in depth, this paper revealed the inherent mechanism of higher grinding temperature in the process of vertical sculptured grinding using the cup wheel. Based on the previous research achievements, the grinding experiments on TC4 (Ti-6A1-4V) and GH4169 are carried out utilizing the self-inhaling internal cooling wheel. The experimental results show that the self-inhaling internal cooling wheel can efficiently reduce the grinding surface temperature. Moreover, the inherent mechanism of reducing the grinding temperature using the internal cooling method is revealed. Meanwhile, under the same grinding conditions, the grinding ratio during the experiments on GH4169 using self-inhaling internal cooling method is about 3 times as high as using conventional external cooling method. And the grinding forces can be reduced by about 20%. This research revealed the inherent mechanism of higher grinding temperature in the process of vertical sculptured grinding using the cup wheel, which provides theoretical basis for the design and application of self-inhaling internal cooling wheel. At the same time, an efficient and non-invasive surface grinding method of TC4 and GH4169 is presented.
基金supported by the General Program (No.60774022)the State Key Program of National Natural Science Foundation of China(No.60834001)the State Key Laboratory of Rail Traffic Control and Safety,Beijing Jiaotong University (No.RCS2009ZT011)
文摘In this paper, iterative learning control (ILC) design is studied for an iteration-varying tracking problem in which reference trajectories are generated by high-order internal models (HOLM). An HOlM formulated as a polynomial operator between consecutive iterations describes the changes of desired trajectories in the iteration domain and makes the iterative learning problem become iteration varying. The classical ILC for tracking iteration-invariant reference trajectories, on the other hand, is a special case of HOlM where the polynomial renders to a unity coefficient or a special first-order internal model. By inserting the HOlM into P-type ILC, the tracking performance along the iteration axis is investigated for a class of continuous-time nonlinear systems. Time-weighted norm method is utilized to guarantee validity of proposed algorithm in a sense of data-driven control.
文摘Objective To evaluate the efficacy of simultaneous anterior and posterior hemivertebra resection in the treatment of congenital kyphoscoliosis caused by fully-segmented hemivertebra. Methods Twenty-one consecutive cases with congenital kyphoscoliosis, which were 8 males and 13 females, underwent one-stage operation of anterior hemivertebra resection and posterior instrumentation. All of the hemivertebra were fully-segmented. The average age at surgery was 11.4 (range, 1.5-16) years old. Results The average follow-up was 23 (range, 6-50) months. The average Cobb's angle of the coronal curve was 51.4° (30°-120°) before surgery, 16.9° (0°-54°) after surgery, and 19.5° at latest follow-up. The angle of segmental kyphosis was 37.1° (0°-95°) before surgery and 16.1° (0°-48°) after surgery, and 18.2° at latest follow-up. Apical translation was improved from 4.7 cm to 1.9 cm. The average fusion segments were 4.8 (range, 2-10) segments. Complication included pressure sore in one case, pedicle cutting by pedicle screw in one case and elongation of the curve in one case. There was no obvious pseudarthrosis, decompensation, and kyohosis deformity aggravation at latest follow-up. Conclusion One-stage hemivortebra resection has a good result in the surgical treatment of congenital kyphoscoliosis caused by fully-segmented hemivertebra, and may shorten fusion levels if performed at an earlier age.
基金Funded by Key Technology R&D Program of Chongqing(No. 2008AC3087)Science & Technology Project of Chongqing Education Committee(No. KJ091414)
文摘Due to low carrying capacity and short life of current ring reducer,we proposed a new planetary gearing with internal gear ring,which consisted of two stages.One was an involute planetary drive and the other was an N-type planetary drive with small teeth difference.The kinematic calculation was conducted based on the analysis of structural composition and working principle.Formulas of backlash calculation for the new planetary gearing were derived by using probabilistic theory and the analytical model was created at the same time.Then,main factors that affect the systematic backlash were introduced and the effects of manufacture error,misaligments and roller bearing parameters on the distribution of backlash were presented.The influence of gear backlash on systematic return difference was performed based on the backlash mathematic model proposed.The results show that the backlash is a little large,of which the backlash of bearing takes a greater part than two gearing stages.So we presented some practical methods to reduce the systematic backlash.
文摘Objective To evaluate the operative technique and preliminary results of video-assisted thoracoscopic anterior correction and fusion of scoliosis. Methods Eleven cases underwent thoracoscopic anterior correction and fusion of scoliosis from March 2003 to April 2005 in our hospital were reviewed. They were all females with an average age of 13.1 years old. Of which, 9 cases were idiopathic scoliosis, 1 case was congenital scoliosis, and 1 case was Marian syndrome scoliosis. The coronal Cobb angle and apical vertebral translation before and after surgery as well as at final follow-up were measured. The operation time, blood loss during operation, and peri-operative complications were recorded. The mean operation time was 6. 4 hours, mean instrumented vertebrae were 6.4 segments, and mean blood loss during operation was 364 mU The coronal Cobb angles of the thoracic curve before and after surgery were 45.5° and 15.4° respectively, with an average correction rate of 65.4%. The lumbar curve was corrected from 28.4° to 11.8° , with an average simultaneous correction rate of 57.2%. All of the patients were followed up regularly with an average time of 21.4 months. At the final foUow-up, the coronal Cobb angles of the thoracic and lumbar curves were 19.0° and 20. 1° , with a 3.6° and 8. 3° loss of correction, respectively. The apical vertebral translation was improved from 32. 3 mm to 10.5 mm for the thoracic curve, and from 13.1 mm to 8.2 mm for the lumbar curve. There were 6 cases with peri-opemtive complications, including 1 case of thoracic effusion, 1 case of chylothomx, 1 case of locking plug loosing, 2 cases of aggravation of the unfused lumbar curve ( 1 case also with thoracolumbar kyphosis), and 1 case with a screw tip causing a contour deformity of the aorta. And 4 of them underwent revision surgery.Conclusions Video-assisted thoracoscopic anterior correction and fusion of scoliosis has good correction capability, less intraoperative bleeding, and favorable cosmetic effect for mild and moderate thoracic scoliosis, but with higher rates of cor- rection loss of the lumbar curve and peri-operative complications. A surgeon should be cautious to perform this technique.
基金Supported by the Ministry of the Environment, Climate Protection and the Energy Sector, Baden-Wuettermberg
文摘In this paper a system combining a diesel reformer using catalytic partial oxidation (CPOX) with the Solid Oxide Fuel Cell (SOFC) for Auxiliary Power Unit (APU) applications is modeled with respect to the cooling effect provided by internal reforming of methane in anode gas channel. A model mixture consisting of 80% n-hexadecane and 20%..!-methylnaphthalin is used to simulate the commercial diesel. The modelling consists of several steps. First, equilibrium gas composition at the exit of CPOX reformer is modelled in terms oxygen to car- bon (O/C) ratio, fuel utilization ratio and anode gas recirculation. Second, product composition, especially methane content, is determined for the me.th.an, ation process at the operating temperatures ra:ng!ng from 500 ℃to 520 ℃.Finally, the cooling power provided by internal reforming of methane in SOFC fuel channel is calculated for two concepts to increase the methane content of the diesel reformate. The results show that the first concept, operating the diesel reformer at low O/C ratio and/or, recirculation rat!o, is not realizable due to high probability of coke formation, whereas the second concept, combining a methanation process with CPOX, can provide a significant cool- ing effect in addition to the conventional c?oling concept which needs higher levels of excess air.
基金Project(50978043) supported by the National Natural Science Foundation of China
文摘The study was motivated by the fact that explosion inside the subway structure may not only cause direct life loss,but also damage the subway structure and lead to further loss of lives and properties.The propagation law of explosion wave in the subway station was analyzed and a simplified model of overpressure in the subway station was also proposed.Whereafter,the improved dynamic cam-clay model of soil and the concrete damaged plasticity constitutive model were used for the dynamic analysis of the subway station.Meanwhile,the influences of soil stiffness and burial depth on the dynamic response of the subway station were looked into.The results show that the multi-peak overpressure in the subway station does not appear,and large stresses concentrate on the central column and the floor slab of the subway station,so some special reinforcement measures should be taken in these parts.The effect of soil stiffness and burial depth on the stress of the central column is little;however,the effect on the stress of the station side wall is relatively obvious.
基金National Science and Technology Support Program(No.2012BAC10B01)Sci-technology Project of Yunnan Province(No.2012CA013)
文摘Many ecosystems extend across national or political boundaries. The consistent and effective protection of these ecosystems in transboundary areas(ETAs) is an important global research focus. Previous research on the protection of such areas can be categorized into seven themes: 1) ecological conservation of a single ETA; 2) investigation of the effects of a single conservation measure on a specific ETA; 3) determination of species-level effects due to ETA conservation; 4) comparison of the same protection measures between different ETAs; 5) introduction of a single conservation measure to a specific ETA; 6) understanding the relationship between conservation and sustainable development; and 7) generalization across multiple ETA conservation cases. The protection of ETAs involves various considerations, including funding support, demand and will for collaboration, community and public participation, historical and cultural factors, political backgrounds, uniqueness of biological resources, formulation of laws and regulations, founding of specialized administrative departments, non-governmental organizations, and fairness. Here, we briefly explain the research themes and considerations related to ETA conservation. The most important finding is that most major research themes do not focus on the challenges of ETA conservation. We use two nature reserves located between China and North Korea as examples to identify specific ways to improve ETA conservation on Changbai Mountains. The efficiency of ETA administration still remains low. The study of ETA conservation should focus on concrete regional information and aim to improve existing measures through the accumulation of experience.
文摘AIM:To assess the impact of macular surgery on the functional and anatomic outcomes of the patients in different grades of epiretinal membrane(ERM).METHODS:Seventy-one eyes of 71 patients who underwent 23-gauge transconjunctival sutureless pars plana vitrectomy for primary isolated ERM were evaluated in this study.RESULTS:There were 38 females(53.5%) and 33 males(46.5%).The average age of the patients was 68.1 y(range 42-89 y).Mean follow up period was 14 mo(range 6-26 mo).The cases were divided into two subgroups of cellophane maculopathy(CM) and macular pucker(MP).An improvement was observed in the postoperative best-corrected visual acuity(BCVA),as well as a decrement in central foveal thickness(CFT) in both groups(both of these being statistically significant;P=0.001).In comparison between two groups,it was found that there was a significant improvement on BCVA and CFT in CM group than MP group(P=0.01).Furthermore,the postoperative fundus findings regarding RPE alterations and macular edema were significantly higher in MP group when compared to the CM group(P=0.01).CONCLUSION:ERM and internal limiting membrane peeling surgery can lead to a significant reduction of CFT and visual improvements in idiopathic ERM.A long-term ERM persistence will cause unrecoverable retinal damage and visual loss.
文摘Internal bond (IB) strength is one of the most important me- chanical properties that indicate particleboard quality. The aim of this study was to find a simple regression model that considers the most important parameters that can influence on IB strength. In this study, IB strength was predicted by three kinds of equations (linear, quadratic, and exponential) that were based on the percentage of adhesive (8%, 9.5%, and 11%), particle size (+5, -5 +8, -8 12, and -12 mesh), and density (0.65, 0.7, and 0.75 g/cm3). Our analysis of the results (using SHAZAM 9 software) showed that the exponential function best fitted the experi- mental data and predicted the IB strength with 18~,/0 error. In order de- crease the error percentage, the Buckingham Pi theorem was used to build regression models for predicting IB strength based on particle size,
基金the Technology Research Program of Shaanxi Province, No. 2009K18-02
文摘The present study observed hemodynamic changes in 26 patients with cerebral arteriosclerosis using a cerebral circulation dynamics detector and transcranial Doppler. In patients with cerebral arteriosclerosis the blood supply and flow rate in the bilateral carotid arteries and the blood flow rate in the anterior cerebral and middle cerebral arteries were similar to normal controls, but the cerebral vascular resistance, critical pressure and pulsatility index were increased, and cerebral arterial elasticity and cerebral blood flow autoregulation were decreased. Compared with the lesioned hemisphere of patients with cerebral infarction, the total blood supply and blood flow rate of patients with cerebral arteriosclerosis were higher. Compared with normal subjects, patients with cerebral arteriosclerosis exhibited cognitive disturbances, mainly in short-term memory, attention, abstract capability, and spatial and executive dysfunction. Results showed that cerebral arteriosclerosis does not directly affect the blood supply of a cerebral hemisphere, but affects cognitive function. The increased cerebral vascular resistance and reduced autoregulation of cerebral blood vessels may be important hemodynamic mechanisms of arteriosclerosis-induced cerebral infarction.
基金Projects(51278367,50878159)supported by the National Natural Science Foundation of ChinaProject(90715040)supported by the Major Research Program of National Natural Science Foundation of China
文摘Analyses of the effects of some parameters were performed to determine the admittance functions in a common two-compartment building with background porosity by the imposed excitation method.Variations of the magnification factors of fluctuating internal pressures were analyzed using 96 model cases under random fluctuating external pressure,and then corresponding design equations were fitted.The results show that the Helmholtz resonance peaks of the admittance functions in both compartments increase with increasing the area of windward or partition wall opening.With increasing the volume of the compartment with an external opening,the resonance peak in this compartment at the higher Helmholtz frequency significantly decreases,at the same time,the resonance peak in the other compartment at the lower Helmholtz frequency also decreases.With increasing the volume of the compartment with background porosity,both resonance peaks in this compartment at the lower and higher Helmholtz frequencies decrease,meanwhile,the resonance peak at the lower Helmholtz frequency for the other compartment also decreases,whereas the resonance peak at the higher Helmholtz frequency increases.Both resonance peaks of the admittance functions in the two compartments decrease with increasing the amplitude of fluctuating external pressure coefficients or reference wind speed.
基金This work was financially supported by the National Natural Science Foundation of China(40576010).
文摘Based on a nonhydrostatic numerical ocean model developed by one of the authors, the interaction of an intemal solitary wave with a step-type topography was investigated. Over the step topography, the flow pattern could be classified into three categories: 1) the propagation and spatial structure of the internal solitary wave was little influenced by the bottom topography, 2) the internal solitary wave was significantly distorted by the blocking effect of the topography without the occurrence of wave breaking and 3) the internal solitary wave was broken as it encountered and passed over the bottom topography. A detailed description of the processes leading to wave breaking is given in this paper together with energy budget analysis. The results revealed that the maximum of the energy dissipation rate is no more than 40%, which is consistent with available experimental data.
基金supported by the US Na tional Science Foundation/International Digital Li brary Program with the Grant Nos.NSF/CISE/IIS 9905833 and NSF/CISE/IIS-0333036.
文摘In this digital era, we have witness the exciting convergence of content, technology, and global collaboration in the development of digital libraries. The mode of universal access for information seeking and knowledge acquisition differs greatly fi'om the traditional ways. From the information resources point of views, the old model of“owning” a collection has given way to “sharing,” and the new emphases have shifted fi'om possessing large “physical libraries” to “virtual libraries” digitally distributed all over the world. “Universal access” has taken on a very different meaning when one has the ability to share invaluable resources through the use of cutting edge technologies. The author has experienced much of these transformations through her own R&D activities-from the creation of interactive videodisc and multimedia CD on the First Emperor of China's terracotta warriors and horses in the 1980s and 1990s to leading a current international digital library project, Global Memory Net (GMNet), supported by the US National Science Foundation. In presenting her vision for linking world digital resources together for universal access, she will share with the audience the latest development of Global Memory Net.
文摘A 55-year-old man was admitted for transcatheter closure because of pulmonary arteriovenous fistula by magnetic resonance angiography (MRA). He had a history of occasional chest pain more than one year. Angiography didn't reveal significant stenosis at coronary artery. The patient was found a continuous grade 2/6 murmur over the left upper parastenal area one month ago. Chest MRA revealed a possible left superior pulmonary arteriovenous fistula. For diagnosis and localization of the fistula, aortography and selective angiography of the intemal mammary artery was performed and presented a left internal mammary artery-to-pulmonary artery fistula. The fistula was successfully closed using an 12 mm domestic vascular plug. Chest MRA showed that the fistula disappeared at two-month follow-up
文摘In today's competitive environment the key element is the differentiation of business which will lead to success. Especially in international markets where there's much more intense competition, it is more important for businesses to enter with innovations that make a difference to their consumers. Innovation is also important for competitive export-oriented production in globalization. In global competition, innovation is the key factor for sustainable success. Increases in the efficiency, profitability of firms make it possible to enter new markets and extend present markets by obtaining advantage of competition. In order to determine accurate strategies, the connection between innovation and exports must be understood better. The aim of this study is to determine the innovation capability and export performance of Turkish export firms. Another aim is to examine the relationship between firm characteristics and innovation capability. Innovation capability of export firms is measured by INNOVSCALE which was developed by Vicente, Abrantes, and Teixeira (2015). Export performance is measured by APEV scale which was developed by Lages, Lages, and Lages (2005). The study uses data collected from 83 firms located in Kayseri. Results obtained by using SPSS indicate that there is a positive relationship between innovation capability and export performance. The results of the ANOVA analysis, innovation capability differ in terms of firm size and export earnings. Innovation capability does not differ in terms of sector, operating years, share of export earnings in the whole revenues, exporting periods, or internationalization levels.
文摘We are living in a multi-polar world under the greater influence of one power. After the shutdown of the government in the US, it can be said that the sole power is about to be challenged. This paper hopes to establish the fact that the future of the international system will continue to be multi-polar. Economic groupings like the Brazil, Russia, India, China, and South Africa (BRICS), Mexico, Indonesia, Singapore and Turkey (MIST) and others denote to this. These groupings may present an alternative to geographically locked but indispensible European Union. Despite the system being multi-polar, the United States dominates the international system. This paper deals with the BRICS countries that propose a bid for power in international relations. Will they have equidistant power form one another or will there be a hierarchy in between them? Can they take/make economic or political decisions? Is a geographically spread power structure more effective in controlling the balances between war and peace? Can they remain objective on trouble spots that may arise in Europe, the Middle East, the Balkans, Asia and the Americas? This paper hopes to achieve the goal of providing a framework for understanding a multi-polar approach to international relations based on the collaboration of BRICS countries. The first part will be the theoretical framework of the paper. The second part will be concerned with American supremacy in foreign relations and the need to question it. The third part will deal with emerging powers but since the most influential "power politics" are steered by China and Russia the main emphasis will be on them. The last part will come to the conclusion.
文摘The strategy audit involves evaluation of the actual direction of a business and comparing that act to the direction required to succeed in a changing environment. A company's actual direction is the sum of what it should and should not do, how well the organisation is internally aligned to support the strategy, and how viable the strategy is when compared to external market, competitor and financial realities. These categories, the internal assessment, and the external or environmental assessment, make up the major elements of a strategy audit. In this paper, it presents such a methodology which ensures an integrated process to evaluate the company's business strategy.