期刊文献+
共找到211篇文章
< 1 2 11 >
每页显示 20 50 100
Fall cone tests considering water content, cone penetration index, and plasticity angle of fine-grained soils 被引量:2
1
作者 Satoru Shimobe Giovanni Spagnoli 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2020年第6期1347-1355,共9页
This paper analyzed the consistency of some parameters of soils in the literature and experimental results from fall cone test and its application to soil plasticity classification.Over 500 data from both literatures ... This paper analyzed the consistency of some parameters of soils in the literature and experimental results from fall cone test and its application to soil plasticity classification.Over 500 data from both literatures and experiments using fall cone and Casagrande methods were compiled to assess the relationships among specified water content,cone penetration index ebT,and plasticity angle eaT of finegrained soils.The results indicate that no unique correlation exists among b,liquid limit of the fall cone test(LLc)and a.The water content at 1 mm cone penetration eC0T correlates well with b,plasticity ratio eRpT(i.e.the ratio of plastic limit to liquid limit),and a.Finally,the potential of using the btan a diagram to classify soil plasticity was also discussed. 展开更多
关键词 Atterberg limits Fall cone test Plasticity angle Water content cone penetration index Plasticity ratio
下载PDF
Experimental study of rock-breaking with an offset single cone bit 被引量:6
2
作者 Chen Yinghua 《Petroleum Science》 SCIE CAS CSCD 2008年第2期179-182,共4页
An experimental study of rock-breaking with an offset single cone bit was completed on the bit bench test equipment. Data such as transmission ratio, weight on bit (WOB), rate of penetration (ROP) and torque on bi... An experimental study of rock-breaking with an offset single cone bit was completed on the bit bench test equipment. Data such as transmission ratio, weight on bit (WOB), rate of penetration (ROP) and torque on bit were acquired in the experiments. Based on analyzing the experimental results, several conclusions were drawn as follows. The transmission ratio of the offset single-cone bit changed slightly with rotary speed of bit, weight on bit and offset distance. The rate of penetration of the offset singlecone bit increased with increase of WOB and off'set distance. The torque on bit increased with increase of offset distance under the same WOB and bit rotary speed, decreased with increase of bit rotary speed under the same WOB. The rock-breaking mechanism of the offset single-cone bit was a scraping action. This indicates that the offset single-cone bit is a chipping type bit. 展开更多
关键词 Offset single-cone bit transmission ratio rate of penetration torque on bit
下载PDF
Hypersonic boundary-layer transition on a flared cone 被引量:20
3
作者 Chuan-Hong Zhang Qing Tang Cun-Biao Lee 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2013年第1期48-53,共6页
Transition on a flared cone with zero angle of at- tack was studied in our newly established Mach 6 quiet wind tunnel (M6QT) via wall pressure measurement and flow visualization. High-frequency pressure transducers ... Transition on a flared cone with zero angle of at- tack was studied in our newly established Mach 6 quiet wind tunnel (M6QT) via wall pressure measurement and flow visualization. High-frequency pressure transducers were used to measure the second-mode waves' amplitudes and frequencies. Using pulsed schlieren diagnostic and Rayleigh scattering technique, we got a clear evolution of the second-mode disturbances. The second-mode waves exist for a long distance, which means that the second-mode waves grow linearly in a large region. Strong Mach waves are radiated from the edge of the boundary layer. With further development, the second-mode waves reach their maximum magnitude and harmonics of the second-mode instability appear. Then the disturbances grow nonlinearly. The second modes become weak and merge with each other. Finally, the nonlinear interaction of disturbance leads to a relatively quiet zone, which further breaks down, resulting in the transition of the bound- ary layer. Our results show that transition is determined by the second mode. The quiet zone before the final breakdown is observed in flow visualization for the first time. Eventual transition requires the presence of a quiet zone generated by nonlinear interactions. 展开更多
关键词 PCB pressure sensor - Pulsed schlieren - Flared cone TRANSITION Second-mode waves
下载PDF
Combined preoperative platelet-to-lymphocyte ratio and serum carbohydrate antigen 19–9 level as a prognostic factor in patients with resected pancreatic cancer 被引量:4
4
作者 Teruhisa Sakamoto Hiroaki Saito +3 位作者 Masataka Amisaki Naruo Tokuyasu Soichiro Honjo Yoshiyuki Fujiwara 《Hepatobiliary & Pancreatic Diseases International》 SCIE CAS CSCD 2019年第3期278-284,共7页
Background: Carbohydrate antigen 19–9(CA19-9) is the most frequently used tumor marker and serves as a prognostic indicator in patients with pancreatic cancer(PC). The platelet-to-lymphocyte ratio(PLR) is thought to ... Background: Carbohydrate antigen 19–9(CA19-9) is the most frequently used tumor marker and serves as a prognostic indicator in patients with pancreatic cancer(PC). The platelet-to-lymphocyte ratio(PLR) is thought to be an inflammation-related serum marker. An elevated PLR represents increased inflammatory status and is associated with poor prognosis in patients with various cancers including PC. Methods: This study involved 103 patients with a histopathological diagnosis of pancreatic ductal adenocarcinoma who underwent pancreatectomy. The patients were assessed to determine the prognostic significance of the combination of the PLR and CA19-9 level. Results: Based on the receiver operating characteristic analysis results, the patients were divided into PLR H igh(PLR ≥ 129.1) andPLRLow(PLR < 129.1) groups and into CA19-9High(CA19-9 ≥ 74.0 U/mL) and CA19-9Low(CA19-9 < 74.0 U/mL) groups. The cumulative 5-year overall survival(OS) and disease-specific survival(DSS) rates significantly differed by both the PLR(PLR H igh group: 19.5% and 22.9%;PLRLow group: 39.1% and 45.9%) and CA19-9(CA19-9 H igh group: 19.1% and 25.6%;CA19-9Low group: 41.0% and 41.0%). We then divided the patients into Groups A(PLR L ow/CA19-9Low), B(PLR Low/CA19-9High or PLRHigh/CA19-9Low), and C(PLR H igh/CA19-9High). The cumulative 5-year OS rates in Groups A, B, and C were 44.0%, 31.9%, and 11.9%, respectively( P = 0.002). The cumulative 5-year DSS rates in Groups A, B, and C were 47.7%, 36.4%, and 16.8%, respectively( P = 0.002). Multivariate analysis revealed that the combination of the PLR and CA19-9 was an independent prognostic factor in patients with resected PC. Conclusions: The combination of the PLR and CA19-9 is useful for predicting the prognosis of patients with resected PC. 展开更多
关键词 CA19-9 PANCREATIC cancer Platelet-to-lymphocyte ratio Prognosis
下载PDF
Lymph node ratio and preoperative CA 19-9 levels predict overall survival and recurrence-free survival in patients with resected pancreatic adenocarcinoma 被引量:4
5
作者 Sabrina C Wentz Zhi-Guo Zhao +5 位作者 Yu Shyr Chan-Juan Shi Kay Washington Nipun B Merchant Fen Xia A Bapsi Chakravarthy 《World Journal of Gastrointestinal Oncology》 SCIE CAS 2012年第10期207-215,共9页
AIM:Clinicopathologic factors predicting overall survival (OS) would help identify a subset to benefit from adjuvant therapy. METHODS: One hundred and sixty-nine patients patients from 1984 to 2009 with curative resec... AIM:Clinicopathologic factors predicting overall survival (OS) would help identify a subset to benefit from adjuvant therapy. METHODS: One hundred and sixty-nine patients patients from 1984 to 2009 with curative resections for pancreatic adenocarcinoma were included. Tumors were staged by American Joint Committee on Cancer 7th edition criteria. Univariate and multivariable analyses were performed using Kaplan-Meier methodology or Cox proportional hazard models. Log-rank tests were performed. Statistical inferences were assessed by two-sided 5% significance level. RESULTS: Median age was 67.1 (57.2-73.0) years with equal gender distribution. Tumors were in the head (89.3%) or body/tail (10.7%). On univariate analysis, adjuvant therapy, lymph node (LN) ratio, histologic grade, negative margin status, absence of peripancreatic extension, and T stage were associated with improved OS. Adjuvant therapy, LN ratio, histologic grade, number of nodes examined, negative LN status, and absence of peripancreatic extension were associated with improved recurrence-free survival (RFS). On multivariable analysis, LN ratio and carbohydrate antigen (CA) 19-9 levels were associated with OS. LN ratio was associated with RFS. CONCLUSION: The LN ratio and CA 19-9 levels are independent prognostic factors following curative resections of pancreatic cancer. 展开更多
关键词 Pancreatic ADENOCARCINOMA LYMPH node ratio CARBOHYDRATE ANTIGEN 19-9 Recurrence-free SURVIVAL Overall SURVIVAL
下载PDF
Effect of Run - in Ratios on the Mechanical Properties of Two - Guide Bars Warp - Knitted Fabrics 被引量:1
6
作者 陈雨梁 《Journal of China Textile University(English Edition)》 EI CAS 2000年第3期87-89,共3页
Warp knitting technology gets rapid development at present and becomes one of the most important parts of the textiles.But it is less known how the parameters of warp knitting technology affect the mechanical properti... Warp knitting technology gets rapid development at present and becomes one of the most important parts of the textiles.But it is less known how the parameters of warp knitting technology affect the mechanical properties of warp-knitted fabrics.This paper presents discuss a research on the relationships between run-in ratio and mechanical properties of the two-bar warp-knittedfabrics through the measurement and analysis of the mechanical properties of various samples with different run-in ratios.The optimal run一in ratios for the reasonable mechanical properties are obtained from above dis- 展开更多
关键词 RUN - in ratios MECHANICAL property TWO - bar WARP - KNITTED fabric .
下载PDF
Change of Ecological Characteristics Due to Decrease of COD/SO_4^(2-) Ratio During Sulfate-reduction 被引量:2
7
作者 王爱杰 任南琪 +1 位作者 刘广民 杜大仲 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2004年第2期151-155,共5页
In order to investigate the change of ecological characteristics due to the decrease of COD/SO_4^(2-) ratio during sulfate reduction, continuous-flew tests were conducted in an acidogenic sulfate-reducing reactor with... In order to investigate the change of ecological characteristics due to the decrease of COD/SO_4^(2-) ratio during sulfate reduction, continuous-flew tests were conducted in an acidogenic sulfate-reducing reactor with molasses wastewater as sole organic carbon source and sodium snlfate as electron acceptor, and the change of pH value, oxidation reduction potential (ORP), volatile fat acids (VFAs), alkalinity (ALK) and the predominant populations with COD/SO_4^(2-) ratio decreasing from 4.2 to 2.0 were investigated. The experimental results demonstrated that, with decreasing COD/SO_4^(2-) ratio, ORP and ALK increased, pH value decreased, and the proportion of acetic acid in terminal products decreased significantly, and a stable -type microbial community with high COD/SO_4^(2-) ratio was converted into a sub -stable -type one with low COD/SO_4^(2-) ratio. 展开更多
关键词 sulfate-reduction COD/SO_4^(2-)ratio ecological characteristic wastewater treatment
下载PDF
Neutrophil-to-lymphocyte ratio and carbohydrate antigen 19-9 as prognostic markers for advanced pancreatic cancer patients receiving first-line chemotherapy 被引量:1
8
作者 Kabsoo Shin Eun-Kyo Jung +3 位作者 Se Jun Park Sangwoon Jeong In-Ho Kim Myung-ah Lee 《World Journal of Gastrointestinal Oncology》 SCIE 2021年第8期915-928,共14页
BACKGROUND A decline in serum carbohydrate antigen 19-9(CA19-9)levels during systemic chemotherapy is considered as a prognostic marker for patients with advanced pancreatic cancer.Neutrophil-to-lymphocyte ratio(NLR)h... BACKGROUND A decline in serum carbohydrate antigen 19-9(CA19-9)levels during systemic chemotherapy is considered as a prognostic marker for patients with advanced pancreatic cancer.Neutrophil-to-lymphocyte ratio(NLR)has been extensively studied as a simple and useful indicator of prognosis in various cancers including pancreatic cancer.AIM To assess the prognostic significance of NLR and CA19-9 in patients with advanced pancreatic adenocarcinoma received first-line chemotherapy according to CA19-9 positivity.METHODS We retrospectively analyzed patients diagnosed with advanced pancreatic cancer who received first-line chemotherapy between January 2010 and July 2017 at the Catholic University of Seoul St.Mary’s Hospital.Patients were divided according to CA19-9 positivity(CA19-9-positive vs-negative groups)and pre-and posttreatment NLR levels.To determine cut-off value of NLR and CA19-9 reduction,time-dependent receiver operating characteristic curve was applied.We evaluated overall survival(OS)and progression-free survival(PFS)for each group using Kaplan-Meier method,and we performed multivariate analyses on the entire cohort.RESULTS We included 271 patients in this study.Cut-off value of NLR and CA19-9 reduction was determined as 2.62 and 18%.Multivariate analysis showed that post-treatment NLR<2.62 and reduction of≥18%of baseline CA19-9 were significantly associated with OS and PFS.Post-treatment NLR≥2.62 showed hazard ratio(HR)of 2.47[95%confidence interval(CI):1.84-3.32,P<0.001]and CA19-9 decline(≥18%)showed HR of 0.51(95%CI:0.39-0.67,P<0.001)for OS.When CA19-9-positive patients were divided into groups according to CA19-9 response(responder vs non-responder)and post-treatment NLR(<2.62 vs≥2.62),CA19-9 responder and post-treatment NLR<2.62 group showed better survival than CA19-9 non-responder and post-treatment NLR≥2.62 group(OS 11.0 mo vs 3.9 mo,P<0.001;PFS 6.3 mo vs 2.0 mo,P<0.001).The combination of CA19-9 decline and post-treatment NLR showed a significant correlation with clinical response in CA 19-9 positive group.Within the CA19-9-negative group,the posttreatment NLR<2.62 group showed better survival than the post-treatment NLR≥2.62 group(OS 12.7 mo vs 7.7 mo,P<0.001;PFS 6.7 mo vs 2.1 mo,P<0.001),and post-treatment NLR showed correlation with clinical response.CONCLUSION In advanced pancreatic cancer patients positive for CA19-9 and treated with systemic chemotherapy,the combination of post-treatment NLR<2.62 and 18%decline of CA19-9 at the first response evaluation is a good prognostic marker.Post-treatment NLR<2.62 alone could be used as a prognostic marker and an adjunctive tool for response evaluation in CA19-9-negative patients. 展开更多
关键词 Pancreatic adenocarcinoma Serum carbohydrate antigen 19-9 Neutrophil-tolymphocyte ratio Multivariate analysis PROGNOSIS CHEMOTHERAPY
下载PDF
Tuning the particle size,physical properties,and photocatalytic activity of Ag_(3)PO_(4)materials by changing the Ag^(+)/PO_(4)^(3-)ratio 被引量:1
9
作者 Hung N M Oanh L T M +4 位作者 Chung D P Thang D V Mai V T Hang L T Minh N V 《Chinese Physics B》 SCIE EI CAS CSCD 2023年第3期561-568,共8页
This study demonstrates the influence of the Ag^(+)/PO_(4)^(3-)ratio in precursor solution on the crystal structural formation,morphology,physical properties,and photocatalytic performance of a Ag_(3)PO_(4)photocataly... This study demonstrates the influence of the Ag^(+)/PO_(4)^(3-)ratio in precursor solution on the crystal structural formation,morphology,physical properties,and photocatalytic performance of a Ag_(3)PO_(4)photocatalyst that is fabricated,using a facile precipitation method,from AgNO_(3)and Na2HPO_(4)·12H_(2)O.The material characterizations were carried out using x-ray diffraction(XRD),scanning electron microscopy(SEM),energy-dispersive x-ray spectroscopy(EDX),Brunauer–Emmett–Teller(BET)surface area,Fourier transform infrared(FTIR)absorption,Raman scattering,x-ray photoelectron spectroscopy(XPS),UV-vis absorption,and photoluminescence(PL).The results show that Ag_(3)PO_(4)crystallizes better when the excess PO_(4)^(3-)content increases,and the lattice parameters decrease slightly,while the crystal diameter and the particle size increase.This change is also observed in the Raman scattering and FTIR spectra with the increase in the vibration frequency of the[PO_(4)]group.The compression of the[PO_(4)]unit was also confirmed in the XPS spectra with the shift of P 2p peaks toward higher binding energy.The photocatalytic results showed that the samples synthesized from excess PO_(4)^(3-)solution exhibited higher photocatalytic performance compared to the sample with a Ag^(+)/PO_(4)^(3-)ratio of 3:1.A sample prepared from the precursor solution with a Ag^(+)/PO_(4)^(3-)ratio of 3:1.5 was optimal for RhB decomposition under both visible light and natural sunlight,completely decomposing 10 ppm RhB after 15 minutes of xenon lamp irradiation and after 60 minutes under solar light irradiation.This is attributed to the high crystallinity,small particle size and low electron–hole recombination rate of the sample. 展开更多
关键词 morphology PHOTOCATALYTIC Ag^(+)/PO_(4)^(3-)ratio visible light
下载PDF
Effects of Different NH_4^+/NO_3^- Ratio and Water Condition on Physiological Characteristics of Rice Seedlings
10
作者 Haimei WU Xiaoyuan CHEN +1 位作者 Yupeng ZHANG Fujie WU 《Agricultural Science & Technology》 CAS 2017年第10期1908-1911,1924,共5页
[Objective] This study aimed to further explore the dynamics of related physiological indexes of rice seedlings under different NH4+ /NO3- ratio and different water condition. [Method] Under the hydroponic condition ... [Objective] This study aimed to further explore the dynamics of related physiological indexes of rice seedlings under different NH4+ /NO3- ratio and different water condition. [Method] Under the hydroponic condition in laboratory, 3 NH4+/NO3- ratios (0/100, 50/50 and 100/0) and 2 water conditions (+PEG,-PEG) were designed for Fengliangyou 7203. [Result] The root-canopy ratio of rice seedlings increased under any of the NH4+/NO3- ratios and water conditions. Under water stress, the root-canopy ratio of rice seedlings changed most greatly at the NH4+/NO3- ratio of 0/ 100; the overall water potential of rice seedlings reached the lowest at the NH4+/ NO3- ratio of 100/0; and the changes of water potential and xylem flow pH were relatively stable at the NH4+/NO3- ratio of 50/50. Under the condition of no water stress, the growth of rice seedlings was best at the NH4+/NO3- ratio of 50/50, followed by the NH4+/NO3- ratios of 0/100 and 100/0. [Conclusion] This study will pro- vide a basis for understanding the relationship between water potential and xylem flow. 展开更多
关键词 Rice NH4+/NO3- ratio Water stress Water potential Root-canopy ratio
下载PDF
In Vitro Study on the Vaporization Ratio of 2-μm Laser in Human Prostatic Tissue
11
作者 杨勇 孙东翀 +3 位作者 魏志涛 徐锋 洪宝发 张旭 《Journal of Huazhong University of Science and Technology(Medical Sciences)》 SCIE CAS 2010年第2期198-200,共3页
In this study, the vaporization ratio of the 2-μm laser in the prostatic tissue with benign prostatic hyperplasia was examined in vitro, to explore a technique to estimate the clearance rate of prostatic tissue durin... In this study, the vaporization ratio of the 2-μm laser in the prostatic tissue with benign prostatic hyperplasia was examined in vitro, to explore a technique to estimate the clearance rate of prostatic tissue during the transurethral vaporesection of the prostate. A total of 9 fresh prostatic tissue specimens were obtained by open surgery and the wet weight of the prostatic tissue were measured immediately after the sample collection. Under the simulated conditions of transurethral vaporesection of the prostate by 2-μm laser, each prostate gland was completely vaporesected into fragments with a diameter of less than 1.0 cm in vitro tissue were collected and measured. Then After the vaporesection, the whole fragments of prostatic the lost weight of prostatic tissue, the weight of the collected prostatic tissue and the ratio of the lost weight of prostatic tissue to the wet weight of the prostate glandular organ specimen were calculated. The correlation between the weight of collected prostatic tissue and the weight of the whole glandular organ was analyzed. All the experimental procedures were carried out by one operator. Wet weight of the prostatic gland specimen and the weight of the harvested prostatic tissues after the procedure were recorded. With respect to the wet weight of prostate gland specimen, the percentage of the weight of collected prostatic tissue was (34.45±1.51) %, and the percentage of the lost weight of prostatic tissue was (65.55±1.51)%. Satisfactory linear relationship was observed between the weight of collected prostatic tissue and the wet weight of prostate gland specimen [y=3.245x=6.475 (t=15.097, P=0.000)]. It is concluded that under the simulated conditions of transurethral vaporesection of the prostate by 2-μm laser, the vaporization ratio of prostatic tissue can be calculated on the basis of the weight of collected prostatic tissue, and thereby the clearance of prostatic tissue during the formal operation by 2-μm laser could be quantitatively determined. 展开更多
关键词 2-μm laser benign prostatic hyperplasia VAPORIZATION ratio
下载PDF
The Paradigm of Surgical Ellipse Dimensions: Are the Length-to-Width Ratio of 3 to 4 and a Vertex Angle of 30&ordm;Correct?
12
作者 Tamara R. Tilleman M. M. Tilleman M. H. A. Neumann 《Surgical Science》 2013年第4期236-240,共5页
Background: It has been postulated that elliptical cutaneous excisions must possess a length-to-width ratio of 3 to 4 and a vertex angle of 30o or less in order to be closed primarily without creating a “dog ear”. T... Background: It has been postulated that elliptical cutaneous excisions must possess a length-to-width ratio of 3 to 4 and a vertex angle of 30o or less in order to be closed primarily without creating a “dog ear”. These dimensions became axiomatic in cutaneous surgery and have been taught in the apprenticeship model for years. The present article examines the validity of that paradigm. Methods: We collected data from two sources: ellipses described in the literature (57 cases);and elliptical excisions performed at the authors’ outpatient clinic (83 cases). The surgical ellipse lengths, widths, and vertex angles were analyzed, and the data were compared to a mathematical formula used to generate a fusiform ellipse. Results: The length-to-width ratio of 3 - 4 was found to be inconsistent with the recommended vertex angle of 30o. In fact, a length-to-width ratio of 3 - 4 determines a vertex angle of 48o - 63o. A 30o vertex angle is only feasible with long length-to-width ration of about 7.5. Conclusions: The paradigm that surgical ellipses should have a vertex angle of 30o with length-to-width ratio of 3 - 4 is incorrect. Evidence from actual surgical practice and from mathematical formulation shows that either the length-to-width ratio must be larger than 3 - 4 or the vertex angle must be larger than 30 degrees. 展开更多
关键词 Elliptical EXCISION Length-to-Width ratio of 3 - 4 30o Vertex Angle
下载PDF
基于RNGk-ε模型的内锥流量计气体流出系数预测 被引量:12
13
作者 徐英 郑建生 +3 位作者 杨会峰 吴经纬 李刚 李巧真 《天津大学学报》 EI CAS CSCD 北大核心 2007年第10期1227-1234,共8页
将计算流体动力学(CFD)气体仿真实验和物理实验相结合,探索不同等效直径比、前后锥角等关键几何参数以及雷诺数对内锥流量计气体流出系数的影响规律.湍流模型为RNGκ-ε模型,实验样机为27种锥体组合结构,实验介质为常温常压空气.仿真实... 将计算流体动力学(CFD)气体仿真实验和物理实验相结合,探索不同等效直径比、前后锥角等关键几何参数以及雷诺数对内锥流量计气体流出系数的影响规律.湍流模型为RNGκ-ε模型,实验样机为27种锥体组合结构,实验介质为常温常压空气.仿真实验表明:等效直径比对内锥流量计气体流出系数有决定性影响;前锥角有较大影响,而后锥角对其影响不显著;流出系数随雷诺数增大而趋于常数.利用实流物理实验标定装置对仿真结果进行验证。气体流出系数的预测精度在2%~7%之间. 展开更多
关键词 内锥流量计 气体流出系数 等效直径比 前后锥角 雷诺数
下载PDF
Transmission Degradation of Femtosecond Laser Pulses in Opened Cone Targets 被引量:1
14
作者 LIU Feng LIN Xiaoxuan +14 位作者 LIU Bicheng DING Wenjun DU Fei LI Yutong MA Jinglong LIU Xiaolong SHENG Zhengming CHEN Liming LU Xin DONG Quanli WANG Weimin WANG Zhaohua WEI Zhiyi CHEN Jiaer ZHANG Jie 《Plasma Science and Technology》 SCIE EI CAS CSCD 2012年第1期24-27,共4页
Irradiated by femtosecond laser pulses with different energies, opened cone targets behave very differently in the transmission of incident laser pulses. The targets, each with an opening angle of 71° and an open... Irradiated by femtosecond laser pulses with different energies, opened cone targets behave very differently in the transmission of incident laser pulses. The targets, each with an opening angle of 71° and an opening of 5 μm, are fabricated using standard semiconductor technology. When the incident laser energy is low and no pre-plasma is generated on the side walls of the cones, the cone target acts like an optical device to reflect the laser pulse, and 15% of the laser energy can be transmitted through the cones. In contrast, when the incident laser energy is high enough to generate pre-plasmas by the pre-pulse of the main pulse that fills the inner cone, the cone with the plasmas will block the transmission of the laser, which leads to a decrease in laser transmission compared with the low-energy case with no plasma. Simulation results using optical software in the low-energy case, and using the particle-in-cell code in the high-energy case, are primarily in agreement with the experimental results. 展开更多
关键词 femtosecond laser pulse cone target transmission ratio
下载PDF
Crustal thickness and v_P/v_S ratio in Shanxi Graben, China 被引量:5
15
作者 Yutao Shi Yuan Gao Honglin Jing 《Earthquake Science》 2014年第6期589-597,共9页
Shanxi Graben is in the middle part of the North China Craton, from south to north. With the teleseismic data recorded by Regional Seismograph Networks and the temporary ZBnet-W Seismic Array around east part of Shanx... Shanxi Graben is in the middle part of the North China Craton, from south to north. With the teleseismic data recorded by Regional Seismograph Networks and the temporary ZBnet-W Seismic Array around east part of Shanxi Graben, we measured the crustal thickness and Vp/Vs ratio beneath each station using the H-K stack of receiver functions. The observed crustal thickness shows obvious lateral variation, increasing gradually from east to west in the Shanxi Graben. Beneath the Shanxi Graben the crust is relatively thicker than both sides of the south and the north. In addition, the Vp/Vs ratio in the north of study zone is higher than that in the south. The highest Vp/Vs ratio exists in the crust of the Xinding basin and the Datong basin. Our study also suggests that high velocity ratio might result from the strong activities of the magmation and volcanism. 展开更多
关键词 Shanxi Graben North China Craton (NCC) Receiver function Crustal thickness - Crustal Vp/Vs ratio
下载PDF
Kinetic Modeling the Formation of Low-mature Gases and Analysis of the Possibility to Be Accumulated 被引量:2
16
作者 SHUAI Yanhua WANG Hui ZHANG Shuichang SU Aiguo 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2008年第3期537-542,共6页
At present, shallow gases have received much attention due to low cost in exploration and production. Low-mature gases, as one significant origin to shallow gas, turns to be an important research topic. The present un... At present, shallow gases have received much attention due to low cost in exploration and production. Low-mature gases, as one significant origin to shallow gas, turns to be an important research topic. The present understanding of low-mature gases is confined within some geological cases, and few laboratory studies have been reported. Therefore, the potential and characters of low- mature gases are not clear up to now. Here, two premature samples (one coal and the other shale) were pyrolyzed in a gold confined system. The gaseous components including hydrocarbon gases and non-hydrocarbon gases were analyzed. Based on kinetic modeling, the formation of low-mature gases was modeled. The results showed that during low mature stage, about 178 mL/gTOC gas was generated from the shale and 100 mL/gTOC from the coal. Two third to three fourth of the generated gases are non-hydrocarbon gases such as H2S and CO2. The total yields of C1-5 for the two samples are almost the same, 30-40 mL/gTOC, but individual gaseous hydrocarbon is different. The shale has much lower C1 but higher C2-5, whereas the coal has higher C1 but lower C2-5. Hydrocarbon gases formed during low-mature stage are very wet. The stable carbon isotope ratios of methane range from -40‰ to -50‰ (PDB), in good consistence with empiric criterion for low-mature gases summed up by the previous researchers. The generation characters suggest that the low-mature gases could be accumulated to form an economic gas reservoir, but most of them occur only as associated gases. 展开更多
关键词 low-mature gases kinetic modeling carbon isotope ratio of methane potential of C1-5
下载PDF
OPTIMIZATION ON ANTENNA PATTERN OF SPACEBORNE SAR WITH IMPROVED NSGA-Ⅱ 被引量:2
17
作者 Xiao Jiang Wang Xiaoqing +1 位作者 Zhu Minhui Xiao Liu 《Journal of Electronics(China)》 2009年第4期443-447,共5页
Optimization of antenna array pattern used in a spaceborne Synthetic Aperture Radar (SAR) system is considered in this study. A robust evolutionary algorithm, Non-dominated Sorting Genetic Algorithms (the improved NS... Optimization of antenna array pattern used in a spaceborne Synthetic Aperture Radar (SAR) system is considered in this study. A robust evolutionary algorithm, Non-dominated Sorting Genetic Algorithms (the improved NSGA-Ⅱ), is applied on a spaceborne SAR antenna pattern design. The system consists of two objective functions with two constraints. Pareto fronts are generated as a result of multi-objective optimization. After being validated by a test problem ZDT4, the algorithms are used to synthesize spaceborne SAR antenna radiation pattern. The good results with low Ambi- guity-to-Signal Ratio (ASR) and high directivity are obtained in the paper. 展开更多
关键词 Synthetic Aperture Radar (SAR) Radiation pattern Improved Non-dominated Sorting Genetic Algorithms (NSGA)- Ambiguity-to-Signal ratio (ASR)
下载PDF
Study on the Maximum Volume of Inscribed Elliptical Cone inside a Cylinder
18
作者 Yusi Niu Liyuan Li 《Journal of Applied Mathematics and Physics》 2018年第9期1793-1815,共23页
The volume of a cone is one third of the volume of a cylinder if they share same base and equal height. Let’s propose a hypothesis, if we expand the research area from cones to elliptical cones, could the maximum rat... The volume of a cone is one third of the volume of a cylinder if they share same base and equal height. Let’s propose a hypothesis, if we expand the research area from cones to elliptical cones, could the maximum ratio of volume beyond one third? This paper tries to pull away the veils of it. Firstly, we present four types of inscribed elliptical cones inside cylinders, and con-sequently all the other inscribed elliptical cones can be classified to these four types. Secondly, for each type of them, this paper discusses the corresponding volume ratio of the inscribed elliptical cone to the cylinder. It is concluded that the largest ratio of the volume of an inscribed cone to that of the cylinder is 1/3. Finally, two types whose ratio could reach 1/3 are given as examples. 展开更多
关键词 Inscribed ELLIPTICAL cone CYLINDER ratio of VOLUME
下载PDF
Methodology for Obtaining Optimal Sleeve Friction and Friction Ratio Estimates from CPT Data
19
作者 Erick Baziw 《International Journal of Geosciences》 CAS 2023年第3期290-303,共14页
Cone penetration testing (CPT) is a cost effective and popular tool for geotechnical site characterization. CPT consists of pushing at a constant rate an electronic penetrometer into penetrable soils and recording con... Cone penetration testing (CPT) is a cost effective and popular tool for geotechnical site characterization. CPT consists of pushing at a constant rate an electronic penetrometer into penetrable soils and recording cone bearing (q<sub>c</sub>), sleeve friction (f<sub>c</sub>) and dynamic pore pressure (u) with depth. The measured q<sub>c</sub>, f<sub>s</sub> and u values are utilized to estimate soil type and associated soil properties. A popular method to estimate soil type from CPT measurements is the Soil Behavior Type (SBT) chart. The SBT plots cone resistance vs friction ratio, R<sub>f</sub> [where: R<sub>f</sub> = (f<sub>s</sub>/q<sub>c</sub>)100%]. There are distortions in the CPT measurements which can result in erroneous SBT plots. Cone bearing measurements at a specific depth are blurred or averaged due to q<sub>c</sub> values being strongly influenced by soils within 10 to 30 cone diameters from the cone tip. The q<sub>c</sub>HMM algorithm was developed to address the q<sub>c</sub> blurring/averaging limitation. This paper describes the distortions which occur when obtaining sleeve friction measurements which can in association with q<sub>c</sub> blurring result in significant errors in the calculated R<sub>f</sub> values. This paper outlines a novel and highly effective algorithm for obtaining accurate sleeve friction and friction ratio estimates. The f<sub>c</sub> optimal filter estimation technique is referred to as the OSFE-IFM algorithm. The mathematical details of the OSFE-IFM algorithm are outlined in this paper along with the results from a challenging test bed simulation. The test bed simulation demonstrates that the OSFE-IFM algorithm derives accurate estimates of sleeve friction from measured values. Optimal estimates of cone bearing and sleeve friction result in accurate R<sub>f</sub> values and subsequent accurate estimates of soil behavior type. 展开更多
关键词 cone Penetration Testing (CPT) Optimal Estimation Geotechnical Site Characterization Sleeve Friction cone Bearing Friction ratio Iterative Forward Modelling (IFM) Soil Behavior Type (SBT)
下载PDF
收益率椭球分布不确定下的均值-CVaR优化研究
20
作者 卿乃侨 《Chinese Quarterly Journal of Mathematics》 2023年第1期85-96,共12页
The article explores a mean-CVaR ratio model with returns distribution uncertainty.To describe the uncertainty of returns distribution,a mixture ellipsoidal distribution absorbing some typical distributions such as th... The article explores a mean-CVaR ratio model with returns distribution uncertainty.To describe the uncertainty of returns distribution,a mixture ellipsoidal distribution absorbing some typical distributions such as the mixture distribution and and ellipsoidal distribution is introduced.Then,by using robust technique with some assumptions,the original robust mean-CVaR ratio model can be formulated as a second-order cone optimization model where the underlying random returns have a mixture ellipsoidal distribution.As an illustration,the corresponding robust optimization models are applied to allocations of assets in securities market.Numerical simulations are presented to illustrate the relation between robustness and optimality and to compare mixture ellipsoidal distribution to some typical distributions as well. 展开更多
关键词 Worst-case mean-CVaR ratio Mixture ellipsoidal uncertainty Second-order cone optimization
下载PDF
上一页 1 2 11 下一页 到第
使用帮助 返回顶部