期刊文献+
共找到41篇文章
< 1 2 3 >
每页显示 20 50 100
Present-day movement characteristics of the Qinghai Nanshan fault and its surrounding area from GPS observation
1
作者 Yang Liu Yuxuan Qiu +5 位作者 Jialiang Liu Luyun Xiong Caijun Xu Jianghui Geng gang zheng Tianchen Sheng 《Geodesy and Geodynamics》 EI CSCD 2024年第2期133-141,共9页
The Qinghai Nanshan fault is a larger fault in the Northeastern Xizang Plateau.In previous studies,its movement characteristics are mainly investigated with geological and seismic observations,and the tectonic transfo... The Qinghai Nanshan fault is a larger fault in the Northeastern Xizang Plateau.In previous studies,its movement characteristics are mainly investigated with geological and seismic observations,and the tectonic transformation role of the fault on its east is not yet clear.This study uses data fusion to obtain denser GPS observations near the Qinghai Nanshan fault.Based on tectonic characteristics,we establish a block model to investigate the fault slip rate,locking degree,and slip deficit.The results show that the Qinghai Nanshan fault slip rate is characterized by sinistral and convergent movement.Both the sinistral and convergent rates display a decreasing trend from west to east.The locking degree and slip deficit are higher in the western segment(with an average of about 0.74 and 1.1 mm/a)and lower in the eastern segment.Then,we construct a strain rate field using GPS observations to analyze the regional strain characteristics.The results indicate that along the fault,the western segment shows a larger shear strain rate and negative dilation rate.Regional earthquake records show that the frequency of earthquakes is lower near the fault.The joint results suggest that the western segment may have a higher earthquake risk.In addition,the insignificant fault slip rate in the eastern segment may indicate that it does not participate in the tectonic transformation among the Riyueshan,Lajishan,and West Qinling faults. 展开更多
关键词 The Qinghai Nanshan fault Movement characteristics Block model Slip rate GPS
原文传递
Effect of sinomenine stellate ganglion block on chronic myocardial ischemia in rats 被引量:1
2
作者 Yan-Qin Wang gang zheng +2 位作者 Jing Qi Jia-Meng Xu Cong Yang 《Journal of Hainan Medical University》 2021年第13期7-11,共5页
Objective:To investigate the protective effect of sinomenine stellate ganglion block(SGB)on chronic myocardial ischemia and its related mechanism.Methods:SD male and female rats(180~200g)were randomly divided into fou... Objective:To investigate the protective effect of sinomenine stellate ganglion block(SGB)on chronic myocardial ischemia and its related mechanism.Methods:SD male and female rats(180~200g)were randomly divided into four groups:blank group,model group,lidocaine group,lidocaine+sinomenine group.The rats in blank group were fed with normal standard diet without modeling,and the other rats were fed with high-fat diet.After 8 weeks of feeding,the rats in high-fat diet group were significantly different from those in blank control group.Then they were randomly divided into 3 groups,10 rats in model group were injected with 0.9%NaCl into right stellate ganglion(RSG)After 2 weeks of continuous injection,pituitrin injection was continuously injected into sublingual vein of rats for 3 days,once every 24 hours;lidocaine group rats were injected with 0.24 mL 1%lidocaine injection in RSG,the rest was the same as model group;lidocaine+sinomenine group rats were injected with 0.24 mL 1%lidocaine injection+0.095 mL sinomenine hydrochloride+2.9 mL 0.8 mL 0.8 mL in RSG,the rest was the same as model group.At the end of the eighth week of the experiment,the rats in the high-fat diet feeding group and the standard ordinary diet feeding group were given the medicine after there was significant difference in blood lipid;before the third injection of pituitrin,the ECG changes of the rats in each group were observed;the general situation of the rats before and after the administration was observed;after the experiment,the blood of the rats in each group was taken from the abdominal aorta,and the serum oxidative stress indexes,such as total superoxide dismutase(SOD)and malondialdehyde,were detected(MDA,IL-6 and cTnI were measured.Results:compared with the blank group,the ECG of the model group changed significantly(P<0.01),the cTnI value increased significantly(P<0.01),indicating that the rat myocardial ischemia model was successfully established;compared with the model group,the SOD level of lidocaine group and lidocaine+sinomenine group increased significantly(P<0.05,P<0.01),the MDA level decreased significantly(P<0.05,P<0.01),IL-6 decreased significantly(P<0.05,P<0.01)05,P<0.01).Conclusion:sinomenine SGB has protective effect on rats with chronic myocardial ischemia,which is related to anti oxidative stress and inhibition of inflammatory reaction. 展开更多
关键词 Myocardial ischemia Stellate ganglion block SINOMENINE Total superoxide dismutase MALONDIALDEHYDE INTERLEUKIN-6
下载PDF
单中心催化剂及其聚烯烃材料的研发进展 被引量:3
3
作者 张晓帆 王伟 +4 位作者 张龙贵 周俊领 郑刚 乔金樑 毛炳权 《高分子材料科学与工程》 EI CAS CSCD 北大核心 2021年第1期141-149,共9页
聚烯烃是一种使用量最大、应用最广,并且生产过程能耗和污染很小的高分子材料,在汽车、包装、建筑、电器、医疗等领域应用十分广泛。随着我国深化供给侧结构性改革,构建国内国际相互促进的新发展格局的推进,解决高端产品自主可控,实现... 聚烯烃是一种使用量最大、应用最广,并且生产过程能耗和污染很小的高分子材料,在汽车、包装、建筑、电器、医疗等领域应用十分广泛。随着我国深化供给侧结构性改革,构建国内国际相互促进的新发展格局的推进,解决高端产品自主可控,实现通用产品高质量发展已成为必然趋势。单中心催化剂及其聚合物产品研发,极大丰富了聚烯烃产品种类,拓展了聚烯烃产品的应用领域。文中概述了单中心催化剂体系组成、各类单中心催化剂的特点及高通量技术在单活性中心催化剂研发中的应用情况,详细介绍了各类主流单中心聚烯烃材料的特点及应用进展,并提出了未来我国单中心催化剂及其产品工业化发展方向。 展开更多
关键词 单中心催化剂 聚烯烃 聚乙烯 聚丙烯 高通量
下载PDF
留学生与近代中国教育经济学的萌生
4
作者 郑刚 余桃桃 《教育与经济》 CSSCI 北大核心 2020年第4期75-82,共8页
留学生是近代中国教育经济学萌生的奠基者和开拓者。他们对教育经济问题的研究,既适应了近代教育事业发展的需要,也符合教育学科发展的趋势。留学生以教育与经济的相互关系、作用及规律为研究对象;研究内容涉及教育经费的筹集分配与使... 留学生是近代中国教育经济学萌生的奠基者和开拓者。他们对教育经济问题的研究,既适应了近代教育事业发展的需要,也符合教育学科发展的趋势。留学生以教育与经济的相互关系、作用及规律为研究对象;研究内容涉及教育经费的筹集分配与使用、教育财政、教育投入与产出等方面;研究方法以实证方法为主。在留学生群体的努力下,近代中国教育经济学的萌生呈现出主体化、科学化、本土化的特点。留学生对教育经济问题的探讨,促进了近代教育事业的发展,推动了中国教育经济学的产生,也为当前构建中国特色教育经济学提供了可资借鉴的历史经验及有益启示。 展开更多
关键词 近代中国 留学生 教育经济学 产生
下载PDF
Treatment of nutcracker syndrome with spermatic vein ligation and iliac vein anastomosis:Case report of three cases 被引量:10
5
作者 Xiao-Yong Gong Wei zheng +5 位作者 Hong Du Yi Lei Ya-Hui Xue Chao-Hui Xue Xian-Chao An gang zheng 《Asian Pacific Journal of Tropical Medicine》 SCIE CAS 2012年第11期923-924,共2页
Three patients with nutcracker syndrome(NCS) were enrolled in the study.Their clinical symptoms mainly included proteinuria and serious varicocele.Color Doppler ultrasound and computed tomography showed that the patie... Three patients with nutcracker syndrome(NCS) were enrolled in the study.Their clinical symptoms mainly included proteinuria and serious varicocele.Color Doppler ultrasound and computed tomography showed that the patients had constricted abdominal aortas,reduced superior mesenteric artery angles,and thinned left renal veins.Patients then underwent left spermatic vein ligation and iliac vein anastomosis.They were checked tliree months after their operation,and results showed that their sperms were improved and their proteinuria disappeared. The color Doppler ultrasound showed new cycle pathways.NCS clinical manifestations are complicated,and need combination diagnosis of symptoms and auxiliary examination to detennine surgical indications.Ligation of spermatic vein and vein anastomosis can be used to treat NCS. 展开更多
关键词 Diagnosis NUTCRACKER SYNDROME Spermatic VEIN TREATMENT VEIN ANASTOMOSIS
下载PDF
Laboratory model study of newly deposited dredger fills using improved multiple-vacuum preloading technique 被引量:7
6
作者 Jingjin Liu Huayang Lei +2 位作者 gang zheng Haizuo Zhou Xuelian Zhang 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2017年第5期924-935,共12页
Problems continue to be encountered concerning the traditional vacuum preloading method in field during the treatment of newly deposited dredger fills.In this paper,an improved multiple-vacuum preloading method was de... Problems continue to be encountered concerning the traditional vacuum preloading method in field during the treatment of newly deposited dredger fills.In this paper,an improved multiple-vacuum preloading method was developed to consolidate newly dredger fills that are hydraulically placed in seawater for land reclamation in Lingang Industrial Zone of Tianjin City,China.With this multiplevacuum preloading method,the newly deposited dredger fills could be treated effectively by adopting a novel moisture separator and a rapid improvement technique without sand cushion.A series of model tests was conducted in the laboratory for comparing the results from the multiple-vacuum preloading method and the traditional one.Ten piezometers and settlement plates were installed to measure the variations in excess pore water pressures and moisture content,and vane shear strength was measured at different positions.The testing results indicate that water dischargeetime curves obtained by the traditional vacuum preloading method can be divided into three phases:rapid growth phase,slow growth phase,and steady phase.According to the process of fluid flow concentrated along tiny ripples and building of larger channels inside soils during the whole vacuum loading process,the fluctuations of pore water pressure during each loading step are divided into three phases:steady phase,rapid dissipation phase,and slow dissipation phase.An optimal loading pattern which could have a best treatment effect was proposed for calculating the water discharge and pore water pressure of soil using the improved multiple-vacuum preloading method.For the newly deposited dredger fills at Lingang Industrial Zone of Tianjin City,the best loading step was 20 kPa and the loading of 40-50 k Pa produced the highest drainage consolidation.The measured moisture content and vane shear strength were discussed in terms of the effect of reinforcement,both of which indicate that the multiple-vacuum preloading method has a better treatment effect not only in decreasing the moisture content and increasing the bearing capacity,but also in increasing the process uniformity at different depths of foundation. 展开更多
关键词 Model tests Vacuum PRELOADING Ultra-soft soil DREDGER FILLS Cost EFFECTIVENESS
下载PDF
Prospective study found that peripheral lymph node sampling reduced the false-negative rate of sentinel lymph node biopsy for breast cancer 被引量:4
7
作者 Chao Han Ben Yang +4 位作者 Wen-Shu Zuo Yan-Song Liu gang zheng Li Yang Mei-Zhu zheng 《Chinese Journal of Cancer》 SCIE CAS CSCD 2016年第6期63-68,共6页
Background:Although sentinel lymph node biopsy(SLNB) can accurately predict the status of axillary lymph node(ALN) metastasis,the high false?negative rate(FNR) of SLNB is still the main obstacle for the treatment of p... Background:Although sentinel lymph node biopsy(SLNB) can accurately predict the status of axillary lymph node(ALN) metastasis,the high false?negative rate(FNR) of SLNB is still the main obstacle for the treatment of patients who receive SLNB instead of ALN dissection(ALND).The purpose of this study was to evaluate the clinical significance of SLNB combined with peripheral lymph node(PLN) sampling for reducing the FNR for breast cancer and to discuss the effect of "skip metastasis" on the FNR of SLNB.Methods:At Shandong Cancer Hospital Affiliated to Shandong University between March 1,2012 and June 30,2015,the sentinel lymph nodes(SLNs) of 596 patients with breast cancer were examined using radiocolloids with blue dye tracer.First,the SLNs were removed;then,the area surrounding the original SLNs was selected,and the visible lymph nodes in a field of 3–5 cm in diameter around the center(i.e.,PLNs) were removed,avoiding damage to the structure of the breast.Finally,ALND was performed.The SLNs,PLNs,and remaining ALNs underwent pathologic examination,and the relationship between them was analyzed.Results:The identification rate of SLNs in the 596 patients was 95.1%(567/596);the metastasis rate of ALNs was 33.7%(191/567);the FNR of pure SLNB was 9.9%(19/191);and after the SLNs and PLNs were eliminated,the FNR was 4.2%(8/191),which was significantly decreased compared with the FNR before removal of PLNs(P Aected number(N) of SLNs,the patients were divided into four groups of N = 0.028).ccording to the det= 1,2,3,and ≥4;the FNR in these groups was 19.6,9.8,7.3,and 2.3%,respectively.For the patients with removal of PLNs was significantly decreased compared with that before remo≤2 or val of P≤3 detected SLNs,the FNR afterLNs(N 3:12.2% vs.4.7%,P ≤ 2:14.0% vs.4.7%,P = 0.019;N ≤ nt(P = 0.021),whereas for patients with ≥4 detected SLNs,the decrease in FNR was not statistically significa= 1.000).In the entire cohorts,the "skip metastasis" rate was 2.5%(15/596);the FNR caused by "skip metastasis" was 2.1%(4/191).Conclusions:The FNR of SLNB was associated with the number of SLNs.For patients with mpling can reduce the FNR of SLNB to an acceptable level of less than 5%.Because of the≤3 detected SLNs,PLN sa existence of the "skip metastasis" and distinct metastasis patterns,the FNR of SLNB cannot be completely eliminated. 展开更多
关键词 Breast cancer Sentinel lymph node biopsy Peripheral lymph node False-negative rate Skip metastasis
下载PDF
Plasticity of language pathways in patients with low-grade glioma A diffusion tensor imaging study 被引量:3
8
作者 gang zheng Xiaolei Chen +7 位作者 Bainan Xu Jiashu Zhang Xueming Lv Jinjiang Li Fangye Li Shen Hu Ting Zhang Ye Li 《Neural Regeneration Research》 SCIE CAS CSCD 2013年第7期647-654,共8页
Knowledge of the plasticity of language pathways in patients with low-grade glioma is important for neurosurgeons to achieve maximum resection while preserving neurological function. The current study sought to invest... Knowledge of the plasticity of language pathways in patients with low-grade glioma is important for neurosurgeons to achieve maximum resection while preserving neurological function. The current study sought to investigate changes in the ventral language pathways in patients with low-grade glioma located in regions likely to affect the dorsal language pathways. The results revealed no significant difference in fractional anisotropy values in the arcuate fasciculus between groups or between hemispheres. However, fractional anisotropy and lateralization index values in the left inferior longitudinal fasciculus and lateralization index values in the left inferior fronto-occpital fasciculus were higher in patients than in healthy subjects. These results indicate plasticity of language pathways in patients with low-grade glioma. The ventral language pathways may perform more functions in patients than in healthy subjects. As such, it is important to protect the ventral language pathways intraoperatively. 展开更多
关键词 可塑性 语言 患者 扩散张量 成像 档次 课程 电子保护
下载PDF
Application of medial column classification in treatment of intraarticular calcaneal fractures 被引量:4
9
作者 gang zheng Fan Xia +1 位作者 Shuang Yang Jun Cui 《World Journal of Clinical Cases》 SCIE 2020年第19期4400-4409,共10页
BACKGROUND There are many types of treatments for calcaneal fractures,including conservative treatment,conventional surgical treatment,and minimally invasive surgery.The choice of specific treatment options is still c... BACKGROUND There are many types of treatments for calcaneal fractures,including conservative treatment,conventional surgical treatment,and minimally invasive surgery.The choice of specific treatment options is still controversial.Open reduction and internal fixation are currently the most commonly used surgical procedures in the clinic.A good fracture reduction effect can be achieved by using the lateral extension incision of the calcaneus;however,many studies have reported a high incidence of postoperative incision complications.Although there are many methods for the classification of intra-articular calcaneal fractures,it is generally believed that the computed tomography(CT)classification proposed by Sanders has high application value in the selection of treatment methods and evaluation of prognosis of calcaneal fractures.However,this method has no clear guiding significance for the choice of surgical incision and surgical plan.AIM To explore the application and clinical efficacy of medial column classification in the treatment of intra-articular calcaneal fractures.METHODS From July 2017 to July 2018,91 patients,including 60 males and 31 females aged 27 to 60 years,were enrolled.All participants had closed intra-articular calcaneal fracture,and their surgical options were selected under the guidance of medial column classification.The patients'fractures were classified according to the Sanders classification:Type II,35 cases;Type III,33 cases;and Type IV,23 cases.Among them,53 patients had medial column displacement(shortened varus)and underwent open reduction and internal fixation with L-lateral incision of the calcaneus;38 patients had no displacement of the medial column and underwent open reduction and internal fixation with tarsal sinus incision.The calcaneus Bohler angle,Gissane angle,length,width,height,and step thickness of the articular surface were evaluated by X-ray and three-dimensional CT before and after surgery and at the last follow-up.Foot function recovery was assessed by the Maryland foot scoring criteria.RESULTS All patients were followed for 5 to 14 mo,with an average of 10.5±2.9 mo.The fractures of all patients healed,and the healing time was 10 to 19 wk,with an average of 10.8±1.5 wk.One patient developed wound infection 1 wk after surgery and was actively debrided and implanted with antibiotic calcium sulfate to control the infection.The patient's fracture healed 5 mo after surgery.One patient developed a sural nerve injury,and the symptoms disappeared 3 mo after surgery.The patients were assessed according to the Maryland foot scoring system:Excellent in 77 cases,good in 10,and fair in 4.The excellent and good rate was 95.6%.CONCLUSION Medial column classification can effectively guide the surgical selection for intraarticular fractures of the calcaneus. 展开更多
关键词 CALCANEUS FRACTURE Medial side Surgical treatment CLASSIFICATION
下载PDF
Intraoperative diffusion tensor imaging predicts the recovery of motor dysfunction after insular lesions 被引量:2
10
作者 Jinjiang Li Xiaolei Chen +6 位作者 Jiashu Zhang gang zheng Xueming Lv Fangye Li Shen Hu Ting Zhang Bainan Xu 《Neural Regeneration Research》 SCIE CAS CSCD 2013年第15期1400-1409,共10页
Insular lesions remain surgically challenging because of the need to balance aggressive resection and functional protection. Motor function deficits due to corticospinal tract injury are a common complication of surge... Insular lesions remain surgically challenging because of the need to balance aggressive resection and functional protection. Motor function deficits due to corticospinal tract injury are a common complication of surgery for lesions adjacent to the internal capsule and it is therefore essential to evaluate the corticospinal tract adjacent to the lesion. We used diffusion tensor imaging to evaluate the corticospinal tract in 89 patients with insular lobe lesions who underwent surgery in Chinese PLA General Hospital from February 2009 to May 2011. Postoperative motor function evaluation revealed that 57 patients had no changes in motor function, and 32 patients suffered motor dysfunction or aggravated motor dysfunction. Of the affected patients, 20 recovered motor function during the 6-12-month follow-up, and an additional 12 patients did not recover over more than 12 months of follow-up. Following reconstruction of the corticospinal tract, fractional anisotropy comparison demonstrated that preoperative, intraoperative and follow-up normalized fractional anisotropy in the stable group was higher than in the transient deficits group or the long-term deficits group. Compared with the transient deficits group, intraoperative normalized fractional anisotropy significantly decreased in the long-term deficits group. We conclude that intraoperative fractional anisotropy values of the corticospinal tracts can be used as a prognostic indicator of motor function outcome. 展开更多
关键词 运动功能 功能障碍 扩散张量 病变 成像 皮质脊髓束 各向异性 封闭
下载PDF
Stomach wall structure and vessels imaging by acoustic resolution photoacoustic microscopy 被引量:2
11
作者 Cheng Wang Yu-Fei Lu +2 位作者 Chun-Miao Cai Hua-Zhong Xiang gang zheng 《World Journal of Gastroenterology》 SCIE CAS 2018年第31期3531-3537,共7页
AIM To image stomach wall blood vessels and tissue, layerby-layer.METHODS We built up the acoustic resolution photoacoustic microscopy(AR-PAM) system for imaging layered tissues, such as the stomach wall. A tunable dy... AIM To image stomach wall blood vessels and tissue, layerby-layer.METHODS We built up the acoustic resolution photoacoustic microscopy(AR-PAM) system for imaging layered tissues, such as the stomach wall. A tunable dye laser system was coupled to a fiber bundle. The fibers of the bundle were placed in nine directions with an incident angle of 45° around a high-frequency ultrasound transducer attached to the acoustic lens. This structure formed a dark field on the tissue surface under the acoustic lens and the nine light beams from the fibers to be combined near the focal point of the acoustic lens. The sample piece was cut from a part of the porcine stomach into a petri dish. In order to realize photoacoustic depth imaging of tumor, we designed a tumor model based on indocyanine green(ICG) dye. The ICG solution(concentration of 129 μM/m L)was mixed into molten gel, and then a gel mixture of ICG(concentration of 12.9 μM/mL) was injected into the stomach submucosa. The injection quantity was controlled by 0.1 mL to make a small tumor model. RESULTS An acoustic resolution photoacoustic microscopy based on fiber illumination was established and an axial resolution of 25 μm and a lateral resolution of 50 μm in its focal zone range of 500 μm has been accomplished. We tuned the laser wavelength to 600 nm. The photoacoustic probe was driven to do B-scan imaging in tissue thickness of 200 μm. The photoacoustic micro-image of mucosa and submucosa of the tissue have been obtained and compared with a pathological photograph of the tissue stained by hematoxylin-eosin staining. We have observed more detailed internal structure of the tissue. We also utilized this photoacoustic microscopy to image blood vessels inside the submucosa. High contrast imaging of the submucosa tumor model was obtained using ICG dye. CONCLUSION This AR-PAM is able to image layer-by-layer construction and some blood vessels under mucosa in the stomach wall without any contrast agents. 展开更多
关键词 PHOTOACOUSTIC IMAGING STOMACH LAYERED tissue ACOUSTIC resolution Fiber
下载PDF
Assessing the deformation response of double-track overlapped tunnels using numerical simulation and field monitoring 被引量:2
12
作者 Yao Hu Huayang Lei +4 位作者 gang zheng Liang Shi Tianqi Zhang Zhichao Shen Rui Jia 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2022年第2期436-447,共12页
The unprecedented rate of metro construction has led to a highly complex network of metro lines.Tunnels are being overlapped to an ever-increasing degree.This paper investigates the deformation response of double-trac... The unprecedented rate of metro construction has led to a highly complex network of metro lines.Tunnels are being overlapped to an ever-increasing degree.This paper investigates the deformation response of double-track overlapped tunnels in Tianjin,China using finite element analysis(FEA)and field monitoring,considering the attributes of different tunneling forms.With respect to the upper tunneling,the results of the FEA and field monitoring showed that the maximum vertical displacements of the ground surface during the tail passage were 2.06 mm,2.25 mm and 2.39 mm obtained by the FEA,field monitoring and Peck calculation,respectively;the heaves on the vertical displacement curve were observed at 8 m(1.25D,where D is the diameter of the tunnel)away from the center of the tunnel and the curve at both sides was asymmetrical.Furthermore,the crown and bottom produce approximately0.38 mm and 1.26 mm of contraction,respectively.The results of the FEA of the upper and lower sections demonstrated that the tunneling form has an obvious influence on the deformation response of the double-track overlapped tunnel.Compared with the upper tunneling,the lower tunneling exerted significantly less influence on the deformation response,which manifested as a smaller displacement of the strata and deformation of the existing tunnel.The results of this study on overlapped tunnels can provide a reference for similar projects in the future. 展开更多
关键词 Double-track overlapped tunnels Deformation response Finite element analysis(FEA) Field monitoring Upper and lower tunneling
下载PDF
Magnetic resonance diffusion tensor imaging-based evaluation of optic-radiation shape and position in meningioma 被引量:1
13
作者 Xueming Lv Xiaolei Chen +5 位作者 Bainan Xu Jiashu Zhang gang zheng Jinjiang Li Fangye Li Guochen Sun 《Neural Regeneration Research》 SCIE CAS CSCD 2012年第9期686-691,共6页
Employing magnetic resonance diffusion tensor imaging, three-dimensional white-matter imaging and conventional magnetic resonance imaging can demonstrate the tumor parenchyma, peritumoral edema and compression on surr... Employing magnetic resonance diffusion tensor imaging, three-dimensional white-matter imaging and conventional magnetic resonance imaging can demonstrate the tumor parenchyma, peritumoral edema and compression on surrounding brain tissue. A color-coded tensor map and three-dimensional tracer diagram were applied to clearly display the optic-radiation location, course and damage. Results showed that the altered anisotropy values of meningioma patients corresponded with optic-radiation shape, size and position on both sides. Experimental findings indicate that the magnetic resonance diffusion tensor imaging technique is a means of tracing and clearly visualizing the optic radiation. 展开更多
关键词 磁共振成像 扩散张量 光辐射 脑膜瘤 位置 形状 评价 三维成像
下载PDF
Measurement of Optical Fiber Geometry Parameters with Bessel Function Fitting Method 被引量:1
14
作者 Yiming Li Huazhong Xiang +3 位作者 Jiankun Tu gang zheng Minghui Chen Bin Jiang 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2021年第2期74-81,共8页
Geometry parameters of optical fiber are crucial in evaluating the quality of the optical fiber.Near⁃field light distribution method is recommended in GB15972.20-2008 for the measurement of geometry parameters.To dist... Geometry parameters of optical fiber are crucial in evaluating the quality of the optical fiber.Near⁃field light distribution method is recommended in GB15972.20-2008 for the measurement of geometry parameters.To distinguish the boundary between fiber core and cladding,it is necessary to illuminate the fiber.The end face of the core is a bright spot with unclear edge,so the true edge of the core and the cladding cannot be accurately judged.A method is proposed in this paper to measure the geometry parameters of optical fiber by Bessel function fitting.Theoretically,the solution to the electromagnetic vector of mode field satisfies Bessel function,and the boundary between the core and the cladding can be precisely extracted by Bessel function fitting.Edges of the fiber were fitted by elliptical curves,and the geometry parameters of the fibers could be calculated.Results show that the maximum deviations of the diameters and the average differences of the fibers were decreased under normal and abnormal conditions respectively.The proposed method is an efficient way to obtain edge data and can improve the accuracy and stability of geometry parameters of optical fibers. 展开更多
关键词 geometry parameters of optical fiber Bessel function edge detect
下载PDF
A Routing Strategy with Link Disruption Tolerance for Multilayered Satellite Networks 被引量:1
15
作者 gang zheng Yanxin Guo 《International Journal of Communications, Network and System Sciences》 2010年第11期835-842,共8页
Link disruption has a considerable impact on routing in multilayered satellite networks, which includes predictable disruption from the periodic satellite motion and unpredictable disruption from communication faults.... Link disruption has a considerable impact on routing in multilayered satellite networks, which includes predictable disruption from the periodic satellite motion and unpredictable disruption from communication faults. Based on the analysis on the predictability of satellite links, a link disruption routing strategy is proposed for multilayered satellite networks, where, a topology period is divided into non-uniform slots, and a routing table in each slot is calculated by the topology predictability of satellite networks, and a congestion control mechanism is proposed to ensure the reliable transmission of packets, and a flooding mechanism is given to deal with the routes selection in the case of unpredictable link disruption. This routing strategy is implemented on the satellite network simulation platform, the simulation results show that the strategy has less delay and higher link utilization, and can meet the routing requirements of multilayered satellite networks. 展开更多
关键词 SATELLITE Networks ROUTING LINK DISRUPTION TOLERANCE
下载PDF
Ground movement induced by triple stacked tunneling with different construction sequences
16
作者 Yao Hu Huayang Lei +4 位作者 gang zheng Liang Shi Tianqi Zhang Zhichao Shen Rui Jia 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2022年第5期1433-1446,共14页
This study tried to explore the ground movement induced by triple stacked tunneling(TST) with different construction sequences. A case study in Tianjin, China was used to investigate the ground movement during the TST... This study tried to explore the ground movement induced by triple stacked tunneling(TST) with different construction sequences. A case study in Tianjin, China was used to investigate the ground movement during the TST(upper tunneling(UT)). For this, a modified Peck formula was proposed to predict the surface settlement induced by TST. Next, three sets of finite element analyses(FEA) were used to compare the effects of construction sequences(i.e. UT, middle tunneling(MT), and lower tunneling(LT)) on vertical and lateral ground displacements. The results of Tianjin case and UT reveal that compared to a Gaussian distribution for a single tunnel, the surface settlement curve of triple stacked tunnels is a bimodal distribution. It seems that the proposed modified Peck formula can effectively predict the surface settlement induced by TST. The results of the three sets of FEA demonstrate that the construction sequence has a significant influence on the ground movement. Among the three construction sequences, the largest lateral displacement is observed in the MT and the smallest one in UT.The existing tunnel has an inhibitory effect on the vertical displacement. The maximum value of the lateral displacement occurs at the depth of the new tunnel in each construction sequence. 展开更多
关键词 Triple stacked tunneling(TST) Ground movement Construction sequence Case study Surface settlement prediction Finite element analysis
下载PDF
Rolling velocity and relative motion of particle detector in local granular flow
17
作者 李然 刘宝林 +1 位作者 郑刚 杨晖 《Chinese Physics B》 SCIE EI CAS CSCD 2022年第11期388-394,共7页
The velocity of a particle detector in granular flow can be regarded as the combination of rolling and sliding velocities.The study of the contribution of rolling velocity and sliding velocity provides a new explanati... The velocity of a particle detector in granular flow can be regarded as the combination of rolling and sliding velocities.The study of the contribution of rolling velocity and sliding velocity provides a new explanation to the relative motion between the detector and the local granular flow.In this study,a spherical detector using embedded inertial navigation technology is placed in the chute granular flow to study the movement of the detector relative to the granular flow.It is shown by particle image velocimetry(PIV)that the velocity of chute granular flow conforms to Silbert’s formula.And the velocity of the detector is greater than that of the granular flow around it.By decomposing the velocity into sliding and rolling velocity,it is indicated that the movement of the detector relative to the granular flow is mainly caused by rolling.The rolling detail shown by DEM simulation leads to two potential mechanisms based on the position and drive of the detector. 展开更多
关键词 local velocity distribution rolling velocity inertial navigation technology relative velocity dependent(RVD)rolling friction
原文传递
A novel particle tracking velocimetry method for complex granular flow field
18
作者 王必得 宋健 +3 位作者 李然 韩韧 郑刚 杨晖 《Chinese Physics B》 SCIE EI CAS CSCD 2020年第1期293-299,共7页
Particle tracking velocimetry(PTV)is one of the most commonly applied granular flow velocity measurement methods.However,traditional PTV methods may have issues such as high mismatching rates and a narrow measurement ... Particle tracking velocimetry(PTV)is one of the most commonly applied granular flow velocity measurement methods.However,traditional PTV methods may have issues such as high mismatching rates and a narrow measurement range when measuring granular flows with large bulk density and high-speed contrast.In this study,a novel PTV method is introduced to solve these problems using an optical flow matching algorithm with two further processing steps.The first step involves displacement correction,which is used to solve the mismatching problem in the case of high stacking density.The other step is trajectory splicing,which is used to solve the problem of a measurement range reduction in the case of high-speed contrast The hopper flow experimental results demonstrate superior performance of this proposed method in controlling the number of mismatched particles and better measuring efficiency in comparison with the traditional PTV method. 展开更多
关键词 particle tracking velocimetry optical flow displacement correction trajectory splicing
原文传递
上一页 1 2 3 下一页 到第
使用帮助 返回顶部