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Special stent for draining the abdominal abscess respectively from colon and duodenum:A case report
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作者 Fu-Long Zhang Jing Xu +5 位作者 Yu-Hong Jiang Yuan-Dong Zhu Qian-Neng Wu Yan Shi Zong-Yuan Zhan Hai Wang 《World Journal of Clinical Cases》 SCIE 2024年第19期3931-3935,共5页
BACKGROUND Postoperative abdominal infections are an important and heterogeneous health challenge.Many samll abdominal abscesses are resolved with antibiotics,but larger or symptomatic abscesses may require procedural... BACKGROUND Postoperative abdominal infections are an important and heterogeneous health challenge.Many samll abdominal abscesses are resolved with antibiotics,but larger or symptomatic abscesses may require procedural management.CASE SUMMARY A 65-year-old male patient who suffered operation for the left hepatocellular carcinoma eight months ago,came to our hospital with recurrent abdominal pain,vomit,and fever for one month.Abdominal computed tomography showed that a big low-density dumbbell-shaped mass among the liver and intestine.Colonoscopy showed a submucosal mass with a fistula at colon of liver region.Gastroscopy showed a big rupture on the submucosal mass at the descending duodenum and a fistula at the duodenal bulb.Under colonoscopy,the brown liquid and pus were drained from the mass with“special stent device”.Under gastroscopy,we closed the rupture of the mass with a loop and six clips for purse stitching at the descending duodenum,and the same method as colonoscopy was used to drain the brown liquid and pus from the mass.The symptom of abdominal pain,vomit and fever were relieved after the treatment.CONCLUSION The special stent device could be effectively for draining the abdominal abscess respectively from colon and duodenum. 展开更多
关键词 Abdominal abscess STENT draining GASTROSCOPY COLONOSCOPY Case report
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Semi-analytical solution for drained expansion analysis of a hollow cylinder of critical state soils 被引量:1
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作者 He Yang Jialiang Zhang +1 位作者 Haisui Yu Peizhi Zhuang 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第6期2326-2340,共15页
The expansion of a thick-walled hollow cylinder in soil is of non-self-similar nature that the stress/deformation paths are not the same for different soil material points.As a result,this problem cannot be solved by ... The expansion of a thick-walled hollow cylinder in soil is of non-self-similar nature that the stress/deformation paths are not the same for different soil material points.As a result,this problem cannot be solved by the common self-similar-based similarity techniques.This paper proposes a novel,exact solution for rigorous drained expansion analysis of a hollow cylinder of critical state soils.Considering stress-dependent elastic moduli of soils,new analytical stress and displacement solutions for the nonself-similar problem are developed taking the small strain assumption in the elastic zone.In the plastic zone,the cavity expansion response is formulated into a set of first-order partial differential equations(PDEs)with the combination use of Eulerian and Lagrangian descriptions,and a novel solution algorithm is developed to efficiently solve this complex boundary value problem.The solution is presented in a general form and thus can be useful for a wide range of soils.With the new solution,the non-self-similar nature induced by the finite outer boundary is clearly demonstrated and highlighted,which is found to be greatly different to the behaviour of cavity expansion in infinite soil mass.The present solution may serve as a benchmark for verifying the performance of advanced numerical techniques with critical state soil models and be used to capture the finite boundary effect for pressuremeter tests in small-sized calibration chambers. 展开更多
关键词 Cavity expansion Drained analysis Boundary effect Critical state soil Non-self-similar Eulerian-Lagrangian approach
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Palliative long-term abdominal drains vs large volume paracenteses for the management of refractory ascites in end-stage liver disease 被引量:1
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作者 Senamjit Kaur Rodrigo V Motta +3 位作者 Bryony Chapman Victoria Wharton Jane D Collier Francesca Saffioti 《World Journal of Hepatology》 2024年第3期428-438,共11页
BACKGROUND Long-term abdominal drains(LTAD)are a cost-effective palliative measure to manage malignant ascites in the community,but their use in patients with end-stage chronic liver disease and refractory ascites is ... BACKGROUND Long-term abdominal drains(LTAD)are a cost-effective palliative measure to manage malignant ascites in the community,but their use in patients with end-stage chronic liver disease and refractory ascites is not routine practice.The safety and cost-effectiveness of LTAD are currently being studied in this setting,with preliminary positive results.We hypothesised that palliative LTAD are as effective and safe as repeat palliative large volume paracentesis(LVP)in patients with cirrhosis and refractory ascites and may offer advantages in patients’quality of life.AIM To compare the effectiveness and safety of palliative LTAD and LVP in refractory ascites secondary to end-stage chronic liver disease.METHODS A retrospective,observational cohort study comparing the effectiveness and safety outcomes of palliative LTAD and regular palliative LVP as a treatment for refractory ascites in consecutive patients with end-stage chronic liver disease followed-up at our United Kingdom tertiary centre between 2018 and 2022 was conducted.Fisher’s exact tests and the Mann-Whitney U test were used to compare qualitative and quantitative variables,respectively.Kaplan-Meier survival estimates were generated to stratify time-related outcomes according to the type of drain.RESULTS Thirty patients had a total of 35 indwelling abdominal drains and nineteen patients underwent regular LVP.The baseline characteristics were similar between the groups.Prophylactic antibiotics were more frequently prescribed in patients with LTAD(P=0.012),while the incidence of peritonitis did not differ between the two groups(P=0.46).The incidence of acute kidney injury(P=0.014)and ascites/drain-related hospital admissions(P=0.004)were significantly higher in the LVP group.The overall survival was similar in the two groups(log-rank P=0.26),but the endpoint-free survival was significantly shorter in the LVP group(P=0.003,P<0.001,P=0.018 for first ascites/drain-related admission,acute kidney injury and drain-related complications,respectively).CONCLUSION The use of LTAD in the management of refractory ascites in palliated end-stage liver disease is effective,safe,and may reduce hospital admissions and utilisation of healthcare resources compared to LVP. 展开更多
关键词 Decompensated liver cirrhosis Indwelling abdominal catheter Rocket drain Palliative care Safety Quality of life
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A coupled strain softening and hardening model for completely weathered granite in a fault zone
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作者 DU Shao-hua XIAO Peng +3 位作者 LI Di-yuan MAO Da-wei RUAN Bo ZHANG Rui-chao 《Journal of Central South University》 SCIE EI CAS CSCD 2024年第9期3225-3241,共17页
his study focused on exploring the specificity of mechanical behavior for completely weathered granite,as a special soil,by consolidated drained triaxial tests.The influences of dry density(1.60,1.70,1.80 and 1.90 g/c... his study focused on exploring the specificity of mechanical behavior for completely weathered granite,as a special soil,by consolidated drained triaxial tests.The influences of dry density(1.60,1.70,1.80 and 1.90 g/cm^(3)),confining pressure(100,200,400 and 600 kPa),and moisture content(13.0%,that is,natural moisture content)were investigated in the present work.A newly developed Duncan-Chang model was established based on the experimental data and Duncan-Chang model.The influence of each parameter on the type of the proposed model curve was also evaluated.The experimental results revealed that with varying dry density and confining pressure,the deviatoric stress–strain curves have diversified characteristics including strain-softening,strain-stabilization and strain-hardening.Under high confining pressure condition,specimens with different densities all showed strain-hardening characteristic.Whereas at the low confining pressure levels,specimens with higher densities gradually transform into softening characteristics.Except for individual compression shear failure,the deformation modes of the specimens all showed swelling deformation,and all the damaged specimens maintained good integrity.Through comparing the experiment results,the strain-softening or strain-hardening behavior of CWG specimens could be predicted following the proposed model with high accuracy.Additionally,the proposed model can accurately characterize the key mechanical indicators,such as tangent modulus,peak value and residual strength,which is simple to implement and depends on fewer parameters. 展开更多
关键词 completely weathered granite mechanical behavior consolidated drained triaxial test constitutive model
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Study of the Efficiency of Vertical Drains by an FEM Method in Soil Treatment for Road Projects: Case of the Development and Bitumination Works of the ROCADE Porto-Novo in Benin
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作者 Cheikh Diallo Diène Vitouley Kossi Ghyslain Joël +1 位作者 Mamadou Tine Apanda Mbongote Johnny 《Open Journal of Civil Engineering》 2024年第3期435-455,共21页
This article aims to study the efficiency of coupled vertical drains for the treatment of long-lasting compressible clay soils for the road project platform of the ring road of Porto Novo, capital of Benin. The experi... This article aims to study the efficiency of coupled vertical drains for the treatment of long-lasting compressible clay soils for the road project platform of the ring road of Porto Novo, capital of Benin. The experimental data allowed us to estimate a consolidation of 29% in 9 months, justifying the drainage of the soil. In order to study the efficiency of drainage, a FEM model was proposed simulating different scenarios. These include a drainless road, pavements equipped with vertical drains with meshes of 0.5 m 0.5 m, 1 m 1 m and 1.5 m 1.5 m respectively and horizontal drains. The results expressed in terms of variations in vertical stresses, effective stresses and shear deformations revealed significant variations in pavement performance depending on the mesh size of the vertical drains. The configuration with a mesh of 0.5 m 0.5 m showed the least deformations, thus indicating a reduction in deformations and better stress distribution. However, the other mesh configurations showed variable results, underlining the importance of choosing the right mesh for the specific project conditions. 展开更多
关键词 PAVEMENT Vertical Drains Horizontal Drains Modelling Plaxis2D ROCADE de Porto-Novo
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Coupling Aquaculture—Crop Productions and Using of Water Drained from Ponds Rearing Clarias gariepinus as Fertilizer for Okra Production (Abelmoschus esculentus var. Clemson spineless, L. Moench)
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作者 Louis Dossou Magblénou Justin Kantoussan +2 位作者 César Bassène Dieynaba Yacine Mar Gueye Hamath Sy 《Open Journal of Applied Sciences》 2024年第9期2628-2647,共20页
The present study concerns the revalorization of drained water from aquaculture ponds rearing Clarias gariepinus on okra crops. The rearing was carried out at the farm of Gaston Berger University in 100 m2 ponds. In e... The present study concerns the revalorization of drained water from aquaculture ponds rearing Clarias gariepinus on okra crops. The rearing was carried out at the farm of Gaston Berger University in 100 m2 ponds. In each pond, the individuals of C. garipinus with an average weight of 6 ± 0.3 g were stocked at a density of 11 per m2. The water temperature and pH were measured during the experiment. The control fishing is carried out every month to monitor variations in the weight and size of reared individuals. The plant production is carried out in elementary plots measuring 3 m × 1.5 m. Each plot was fertilized with either: drained water from C. gariepinus rearing (DWC), poultry droppings (PD), cow dung (CD) and mineral fertilizer (NPK). Treatments are carried out in tripliqua with either river water (RW), RW + the recommended dose of NPK (RD-NPK), RW + RD-PD, RW + RD-CD, DWC, DWC + 25% RD-NPK, DWC + 50% RD-NPK, DWC + 75% RD-NPK, DWC + 25% RD-PD, DWC + 50% RD-PD, DWC + 75% RD-PD, DWC + 25% RD-CD, DWC + 50% RD-CD, DWC + 75% RD-CD. Growth parameters and yield of okra were determined. The average temperature in the rearing environment was 27.6 ± 1.5˚C and pH 7.9 ± 1.1. After six (06) months of rearing, C. gariepinus individuals reached an average weight of 850.12 ± 1.3 g and an average height of 52.44 ± 1.1 cm. The daily weight gain and specific growth rates over this period were 3.9 g per day and 2.8% per day, respectively. The treatment T1 (RW + DR-NPK) gave the highest mean collar diameter and mean plant height with 2.3 ± 0.9 cm and 61.6 ± 32 cm, respectively. In T4 (DWC), the mean height of plants was 38.8 ± 23.5 cm and mean collar diameter 1.4 ± 0.8 cm. The growth performance in T4 was comparable to that of RD-CD (T3), but different from RD-NPK (T1) and RD-PD (T2). The highest average number, average weight, average length and average diameter of fruits were noted in treatments T13 (RW + RD-75%CD) and T7 (DWC + 75% RD-NPK). The best yields were noted in T1 (RW + RD-NPK) = 10.8 ± 5.4 t·ha−1, T5 (DWC + 25% RD-NPK) = 9.2 ± 4.6 t·ha−1 and T4 (DWC) = 8.6 ± 4.3 t·ha−1 which are comparable and higher than those obtained in T2 = 5.7 ± 2.8 t·ha−1 and T3 = 7.5 ± 3.8 t·ha−1. 展开更多
关键词 Integrated Aquaculture Drained Water FERTILIZATION C. gariepinus OKRA
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基于DEFORM-3D的铝合金某型号工字形模锻件成形工艺优化
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作者 陈月雁 刘强 李丹丹 《铝加工》 CAS 2024年第3期59-64,共6页
针对某型号工字形模锻件存在的穿流缺陷,结合DEFORM-3D仿真软件及对金属流线和流线缺陷的研究,提出了避免穿流缺陷的有效措施。根据生产实际,应用DEFORM-3D仿真软件,提出了3种坯料优化方案。考虑到制坯难度与成本,选取坯料优化方案2进... 针对某型号工字形模锻件存在的穿流缺陷,结合DEFORM-3D仿真软件及对金属流线和流线缺陷的研究,提出了避免穿流缺陷的有效措施。根据生产实际,应用DEFORM-3D仿真软件,提出了3种坯料优化方案。考虑到制坯难度与成本,选取坯料优化方案2进行试制。但取样分析结果表明,试制锻件穿流缺陷得到了一定程度的改善,却仍不能满足客户需求。进一步进行预锻件设计,确定合适的设计方案并进行试制。取样分析结果表明,试制锻件低倍组织均匀,金属流线合理分布,未见穿流缺陷,锻件质量满足客户需求。 展开更多
关键词 工字形模锻件 穿流 工艺优化
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RESEARCH ON GUARANTEED WATER DEPTH FOR SAFE DRAINING AT ZUYUAN SEWAGE OUTLET
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作者 Wang Guangping Senior Engineer, Shanghai Investigation and Design Institute, Shanghai 《China Ocean Engineering》 SCIE EI 1990年第2期231-240,共10页
To select the location of sewage outlet in the sewage disposal program of Shanghai is a rather comprehensive problem which covers many fields and has great influences. The sewage outlet at Zuyuan, about 10 km away fro... To select the location of sewage outlet in the sewage disposal program of Shanghai is a rather comprehensive problem which covers many fields and has great influences. The sewage outlet at Zuyuan, about 10 km away from Wusongkou, is situated on the south bank of the South Channel in the Yangtze Estuary. In order to determine the water depth which can guaranteed the safe draining of sewage at the outlet, a statistical method is adopted in this paper for the determination of the guarantee rate of safe draining at Zuyuan sewage outlet by means of the characteristics of fluvial process and previous topographic data, and the guaranteed water depth for safe draining is then determined. 展开更多
关键词 RESEARCH ON GUARANTEED WATER DEPTH for SAFE draining AT ZUYUAN SEWAGE OUTLET SAFE AT
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Ambipolar performance improvement of the C-shaped pocket TFET with dual metal gate and gate–drain underlap
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作者 赵梓淼 陈子馨 +9 位作者 刘伟景 汤乃云 刘江南 刘先婷 李宣霖 潘信甫 唐敏 李清华 白伟 唐晓东 《Chinese Physics B》 SCIE EI CAS CSCD 2023年第10期700-707,共8页
Dual-metal gate and gate–drain underlap designs are introduced to reduce the ambipolar current of the device based on the C-shaped pocket TFET(CSP-TFET).The effects of gate work function and gate–drain underlap leng... Dual-metal gate and gate–drain underlap designs are introduced to reduce the ambipolar current of the device based on the C-shaped pocket TFET(CSP-TFET).The effects of gate work function and gate–drain underlap length on the DC characteristics and analog/RF performance of CSP-TFET devices,such as the on-state current(I_(on)),ambipolar current(I_(amb)),transconductance(g_(m)),cut-off frequency(f_(T))and gain–bandwidth product(GBP),are analyzed and compared in this work.Also,a combination of both the dual-metal gate and gate–drain underlap designs has been proposed for the C-shaped pocket dual metal underlap TFET(CSP-DMUN-TFET),which contains a C-shaped pocket area that significantly increases the on-state current of the device;this combination design substantially reduces the ambipolar current.The results show that the CSP-DMUN-TFET demonstrates an excellent performance,including high I_(on)(9.03×10^(-4)A/μm),high I_(on)/I_(off)(~10^(11)),low SS_(avg)(~13 mV/dec),and low I_(amb)(2.15×10^(-17)A/μm).The CSP-DMUN-TFET has the capability to fully suppress ambipolar currents while maintaining high on-state currents,making it a potential replacement in the next generation of semiconductor devices. 展开更多
关键词 tunnel field effect transistor ambipolar current dual metal gate gate–drain underlap
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Recent evidence for subcutaneous drains to prevent surgical site infections after abdominal surgery:A systematic review and metaanalysis
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作者 Tomohiro Ishinuki Hiroji Shinkawa +16 位作者 Keita Kouzu Seiichi Shinji Erika Goda Toshio Ohyanagi Masahiro Kobayashi Motomu Kobayashi Katsunori Suzuki Yuichi Kitagawa Chizuru Yamashita Yasuhiko Mohri Junzo Shimizu Motoi Uchino Seiji Haji Masahiro Yoshida Hiroki Ohge Toshihiko Mayumi Toru Mizuguchi 《World Journal of Gastrointestinal Surgery》 SCIE 2023年第12期2879-2889,共11页
BACKGROUND Surgical site infections(SSIs)increase mortality,hospital stays,additional medical treatment,and medical costs.Subcutaneous drains prevent SSIs in gynecological and breast surgeries;however,their clinical i... BACKGROUND Surgical site infections(SSIs)increase mortality,hospital stays,additional medical treatment,and medical costs.Subcutaneous drains prevent SSIs in gynecological and breast surgeries;however,their clinical impact in abdominal surgery remains unclear.AIM To investigate whether subcutaneous drains were beneficial in abdominal surgery using a systematic review and meta-analysis.METHODS The database search used PubMed,MEDLINE,and the Cochrane Library.The following inclusion criteria were set for the systematic review:(1)Randomized controlled trial studies comparing SSIs after abdominal surgery with or without subcutaneous drains;and(2)Studies that described clinical outcomes,such as SSIs,seroma formation,the length of hospital stays,and mortality.RESULTS Eight studies were included in this meta-analysis.The rate of total SSIs was significantly lower in the drained group(54/771,7.0%)than in the control group(89/759,11.7%),particularly in gastrointestinal surgery.Furthermore,the rate of superficial SSIs was slightly lower in the drained group(31/517,6.0%)than in the control group(49/521,9.4%).No significant differences were observed in seroma formation between the groups.Hospital stays were shorter in the drained group than in the control group.CONCLUSION Subcutaneous drains after abdominal surgery prevented SSIs and reduced hospital stays but did not significantly affect seroma formation.The timing of drain removal needs to be reconsidered in future studies. 展开更多
关键词 Abdominal surgery MORTALITY Seroma formation Subcutaneous drain Surgical site infections
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水平联合竖直排水板真空预压处理工程废浆试验研究 被引量:2
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作者 刘飞禹 李航 +3 位作者 王军 符洪涛 李校兵 蔡瑛 《土木与环境工程学报(中英文)》 CSCD 北大核心 2024年第3期24-32,共9页
传统真空预压法(VP)在加固工程废浆时存在预制竖向排水板(PVD)易淤堵、周围土体形成土柱以及真空度随深度衰减等问题,考虑到预制水平排水板(PHD)在真空预压法处理软土地基中的特点,提出一种水平联合竖直排水板真空预压(PHD-PVD-VP)处理... 传统真空预压法(VP)在加固工程废浆时存在预制竖向排水板(PVD)易淤堵、周围土体形成土柱以及真空度随深度衰减等问题,考虑到预制水平排水板(PHD)在真空预压法处理软土地基中的特点,提出一种水平联合竖直排水板真空预压(PHD-PVD-VP)处理工程废浆的方法。通过4组大型室内模型试验,对工程废浆加固过程中的排水、沉降以及孔隙水压力进行监测,并借助扫描电镜得到的排水板滤膜微观图片,分析不同初始PHD真空压力下PHD-PVD-VP对工程废浆的加固效果。试验结果表明,PHD-PVD-VP处理工程废浆时减少了土颗粒径向移动速率,延缓“土柱”的形成及缓解土颗粒嵌入排水板滤膜的淤堵效应,提升了土体整体固结效果;40 kPa的初始PHD真空压力使PHD-PVD-VP对工程废浆的排水固结效果最佳,处理后土体的平均含水率和十字板剪切强度分别为40.9%和25.5 kPa,有效地缓解了PHD和PVD的淤堵并改善了土体固结的均匀性。通过微观结构分析发现,PHD初始真空压力的大小同时影响着PHD与PVD滤膜的淤堵情况,从而影响其排水性能,40 kPa的初始PHD真空压力使得两种排水板的排水性能都得到充分发挥。 展开更多
关键词 真空预压 水平排水板 工程废浆 防淤堵 固结度
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页岩气分离器阀套式排污阀冲蚀特性研究 被引量:1
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作者 刘恩斌 李茜 +2 位作者 寇博 姜军 李党建 《中国安全科学学报》 CAS CSCD 北大核心 2024年第5期52-60,共9页
为解决页岩气开采过程中砂粒经过分离器后对排污阀造成严重冲蚀的问题,以长宁页岩气田某井为例,基于FLUENT软件,采用数值模拟的方法模拟在不同速度、砂量、粒径、形状系数和阀门开度情况下砂粒对排污阀冲蚀特性,并评估影响排污阀冲蚀特... 为解决页岩气开采过程中砂粒经过分离器后对排污阀造成严重冲蚀的问题,以长宁页岩气田某井为例,基于FLUENT软件,采用数值模拟的方法模拟在不同速度、砂量、粒径、形状系数和阀门开度情况下砂粒对排污阀冲蚀特性,并评估影响排污阀冲蚀特性的主要因素,明确排污阀的冲蚀情况。结果表明:阀瓣与节流孔冲蚀破坏是造成排污阀失效的主要原因;随着阀门开度减小,阀内压差呈指数式增长,在阀瓣和节流孔处流速最大,砂粒形状系数减小,对阀门冲蚀越严重;基于敏感性分析,各因素对阀门冲蚀特性影响程度为:ξ_(l)(速度)=0.73,ξ_(m)(砂粒粒径)=0.71,ξ_(n)(砂量)=0.70,ξ_(q)(形状系数)=0.67。因此,建议通过增大阀门内部流通面积将流体流速控制在7m/s以内,提高除砂器除砂能力,避免粒径较大的砂粒(砂粒粒径>60μm)进入排污阀,将进入排污阀的砂粒粒径控制在60μm内,为现场设备评价优化提供有效手段。 展开更多
关键词 页岩气 分离器 阀套式排污阀 冲蚀特性 数值模拟
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正反向排水板真空预压法在地基处理工程中的应用
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作者 武亚军 陈浩 +2 位作者 VU Quoc Vuong 陈国公 陈先叠 《水运工程》 2024年第7期217-225,238,共10页
目前真空预压法加固软土地基中排水板负压源通常位于顶部,由于真空度沿竖向的衰减,普通真空预压对深层土体的加固效果较差。为此提出了正反向排水板相结合的排水方式,正向排水板的负压源在排水板顶部,反向排水板的负压源在排水板的底部... 目前真空预压法加固软土地基中排水板负压源通常位于顶部,由于真空度沿竖向的衰减,普通真空预压对深层土体的加固效果较差。为此提出了正反向排水板相结合的排水方式,正向排水板的负压源在排水板顶部,反向排水板的负压源在排水板的底部。将正反向排水板结合真空预压应用于温州某地基处理工程中,对地表沉降、真空度、孔隙水压力等指标的监测结果显示,平均固结度达到93.1%。相同工况下正反向排水板结合真空预压数值模拟得到的地表沉降大于正向排水板结合真空预压得到的地表沉降,增长率达到12.9%;相同工况下正反向排水板结合真空预压数值模拟得到的孔隙水压力在3~10 m范围内的消散情况明显优于正向排水板结合真空预压,地基加固效果更好。正反向排水板结合真空预压方法值得在工程中进一步推广应用。 展开更多
关键词 基础工程 正反向排水板 真空预压 地表沉降 数值模拟 固结度
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适用于SiC MOSFET的漏源电压积分自适应快速短路保护电路研究 被引量:1
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作者 李虹 胡肖飞 +1 位作者 王玉婷 曾洋斌 《中国电机工程学报》 EI CSCD 北大核心 2024年第4期1542-1552,I0024,共12页
SiC MOSFET因其高击穿电压、高开关速度、低导通损耗等性能优势而被广泛应用于各类电力电子变换器中。然而,由于其短路耐受时间仅为2~7μs,且随母线电压升高而缩短,快速可靠的短路保护电路已成为其推广应用的关键技术之一。为应对不同... SiC MOSFET因其高击穿电压、高开关速度、低导通损耗等性能优势而被广泛应用于各类电力电子变换器中。然而,由于其短路耐受时间仅为2~7μs,且随母线电压升高而缩短,快速可靠的短路保护电路已成为其推广应用的关键技术之一。为应对不同母线电压下的Si C MOSFET短路故障,文中提出一种基于漏源电压积分的自适应快速短路保护方法(drain-sourcevoltageintegration-basedadaptivefast short-circuit protection method,DSVI-AFSCPM),研究所提出的DSVI-AFSCPM在硬开关短路(hardswitchingfault,HSF)和负载短路(fault under load,FUL)条件下的保护性能,进而研究不同母线电压对DSVI-AFSCPM的作用机理。同时,探究Si CMOSFET工作温度对其响应速度的影响。最后,搭建实验平台,对所提出的DSVI-AFSCPM在发生硬开关短路和负载短路时不同母线电压、不同工作温度下的保护性能进行实验测试。实验结果表明,所提出的DSVI-AFSCPM在不同母线电压下具有良好的保护速度自适应性,即母线电压越高,短路保护速度越快,并且其响应速度受Si CMOSFET工作温度影响较小,两种短路工况下工作温度从25℃变化到125℃,短路保护时间变化不超过90 ns。因此,该文为Si CMOSFET在不同母线电压下的可靠使用提供一定技术支撑。 展开更多
关键词 碳化硅金属氧化物半导体场效应晶体管 短路保护 漏源电压积分 母线电压 自适应
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三门峡水库控制运用方式的优化探讨
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作者 郭彦 侯素珍 +3 位作者 杨飞 王平 胡恬 赖瑞勋 《水电能源科学》 北大核心 2024年第7期202-206,39,共6页
三门峡水库“蓄清排浑”运用为多沙河流的治理提供了宝贵经验,随着来水来沙情况的变化及对水库功能需求和对水库泥沙冲淤规律认识的深化,该运行方式亦在实践中不断调整和完善。为此,针对不同的典型年份设定集中敞泄与分段敞泄的敞泄排... 三门峡水库“蓄清排浑”运用为多沙河流的治理提供了宝贵经验,随着来水来沙情况的变化及对水库功能需求和对水库泥沙冲淤规律认识的深化,该运行方式亦在实践中不断调整和完善。为此,针对不同的典型年份设定集中敞泄与分段敞泄的敞泄排沙方案,采用一维非恒定水沙数学模型,对选取的2018~2019年丰水少沙年和2014~2016年枯水少沙年设定12种控制运用方案进行模拟,比较各方案下库区冲淤变化的优劣,据此选取适合三门峡水库的控制运用方式。结果表明,2018~2019年分段敞泄方案的冲刷效果优于集中敞泄方案,即使在后汛期的控制水位抬高至310 m,也能达到较好的冲刷效果;2014~2016年分段敞泄方案虽优于集中敞泄方案,但其冲刷主要集中于2014年汛期,2015、2016年整体呈淤积状态,综合考虑建议枯水少沙年份水库采用“泥沙年际调节”运用模式。 展开更多
关键词 一维水沙模型 控制运用方式 敞泄排沙 冲淤变化 三门峡水库
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GaN HEMT源漏通道区电阻的自热和准饱和效应模型
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作者 姚若河 姚永康 耿魁伟 《华南理工大学学报(自然科学版)》 EI CAS CSCD 北大核心 2024年第7期1-8,共8页
GaN HEMT在栅极与源极和漏极之间存在一段通道区域,在等效电路模型中通常等效为一电阻,称为源漏通道区电阻R_(D,S)。准确构建GaN HEMT R_(D,S)模型,对于分析GaN HEMT直流和射频特性,构建GaN HEMT大信号模型具有十分重要的意义。本研究... GaN HEMT在栅极与源极和漏极之间存在一段通道区域,在等效电路模型中通常等效为一电阻,称为源漏通道区电阻R_(D,S)。准确构建GaN HEMT R_(D,S)模型,对于分析GaN HEMT直流和射频特性,构建GaN HEMT大信号模型具有十分重要的意义。本研究给出考虑自热和准饱和效应的R_(D,S)模型。首先由源漏通道区温度T_(CH)与耗散功率P_(diss)的关系,推导出非线性自热效应模型。进一步基于准饱和效应和Trofimenkoff模型,给出源漏通道区电子漂移速度与电场强度的关系表达式,构建非线性R_(D,S)模型。在环境温度Tamb=300~500 K时,源漏通道区二维电子气2DEG面密度n_(S,acc)(T_(CH))和迁移率μ_(acc)(T_(CH))随T_(CH)的升高而下降,这导致低偏置条件下的源漏通道区电阻R_(D0,S0)随T_(CH)呈非线性增长。将本研究和文献报道的R_(D,S)模型与TCAD(Technology Computer Aided Design)仿真数据进行对比,结果显示:本研究与文献报道的漏通道区电阻RD模型的平均相对误差分别为0.32%和1.78%,均方根误差(RMSE)分别为0.039和0.20Ω;RS模型的平均相对误差分别为0.76%和1.73%,RMSE分别为0.023和0.047Ω。与文献报道的实验数据进行对比,结果显示:本研究与文献RD模型的平均相对误差分别为0.91%和1.59%,RMSE分别为0.012和0.015Ω;RS平均相对误差分别为1.22%和2.77%,RMSE分别为0.0015和0.0034Ω。本研究提出的R_(D,S)模型具有更低的平均相对误差和均方根误差,能够更加准确地表征GaN HEMT线性工作区R_(D,S)随漏源电流I_(DS)的变化。可将本模型用于器件的设计优化,也可作为Spice模型用于电路仿真。 展开更多
关键词 源漏通道区电阻 GaN HEMTs 自热效应 准饱和效应
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高压大功率SiC MOSFETs短路保护方法
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作者 汪涛 黄樟坚 +3 位作者 虞晓阳 张茂强 骆仁松 李响 《高电压技术》 EI CAS CSCD 北大核心 2024年第4期1583-1595,共13页
碳化硅(SiC)MOSFETs短路承受能力弱,研究其短路保护方法成为保障电力电子设备安全运行的重要课题。现有方法大多围绕低压小功率SiC MOSFETs,然而随着电压和功率等级的提升,器件特性有所差异,直接套用以往设计难以实现高压大功率SiC MOSF... 碳化硅(SiC)MOSFETs短路承受能力弱,研究其短路保护方法成为保障电力电子设备安全运行的重要课题。现有方法大多围绕低压小功率SiC MOSFETs,然而随着电压和功率等级的提升,器件特性有所差异,直接套用以往设计难以实现高压大功率SiC MOSFETs的快速、可靠保护。该文首先详细研究了几种常用短路检测方法;其次基于高压大功率SiC MOSFETs器件特性,深入对比分析了不同短路检测方法的适用性,提出一种阻容式漏源极电压检测和栅极电荷检测相结合的短路保护方法;最后搭建了实验平台验证所提方法的可行性。结果表明,提出的方法在硬开关短路故障(hard switching fault,HSF)下,保护响应时间缩短了1.4μs,短路能量降低了62.5%;且能可靠识别负载短路故障(fault under load,FUL)。 展开更多
关键词 SiC MOSFETs 高压大功率 短路保护 器件特性 漏源极电压 栅极电荷
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龙江振兴背景下大学生留省就业思想行为引导策略研究
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作者 李东 张诗琳 +2 位作者 宋志彬 孟祥伟 房丹丹 《林业科技情报》 2024年第1期216-218,共3页
随着东北振兴战略的持续深入实施,黑龙江作为东北地区的一个重要省份,正在积极推进经济、社会和文化的全面振兴和发展。在龙江振兴的大背景下,大学生留省就业对于地方经济的发展、人才储备的完善以及区域竞争力的提升具有重要意义。然而... 随着东北振兴战略的持续深入实施,黑龙江作为东北地区的一个重要省份,正在积极推进经济、社会和文化的全面振兴和发展。在龙江振兴的大背景下,大学生留省就业对于地方经济的发展、人才储备的完善以及区域竞争力的提升具有重要意义。然而,当前黑龙江省大学生留省就业还面临诸多不利因素,因此,该文旨在分析这些问题,并提出促进大学生留省就业的思想行为引导策略。 展开更多
关键词 大学生 留省就业 人才流失 择业观念 就业指导
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碎石桩-排水板组合型复合地基固结解析解
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作者 李传勋 刘聪 陆向综 《工程科学与技术》 EI CAS CSCD 北大核心 2024年第4期130-140,共11页
碎石桩-排水板组合型复合地基以成本低、固结速率快及加固效果好等优势被广泛应用于工程实际。虽然目前竖井地基或碎石桩复合地基固结理论已较为完善,但同时包含以上两种排水体的复合地基固结理论还鲜见报道。此外,以往固结模型中土体... 碎石桩-排水板组合型复合地基以成本低、固结速率快及加固效果好等优势被广泛应用于工程实际。虽然目前竖井地基或碎石桩复合地基固结理论已较为完善,但同时包含以上两种排水体的复合地基固结理论还鲜见报道。此外,以往固结模型中土体内孔隙水在径向仅发生单向渗流,这与实际情况存在差别。基于此,以碎石桩-排水板组合型复合地基为研究对象,考虑外荷载作用下土中孔隙水分别向碎石桩和排水板发生径向渗流,在复合地基顶面排水、底面不透水条件下建立碎石桩-排水板复合地基固结模型。利用桩体、桩周土体和竖井间流量相等的连续条件,获得该模型的解析解答。在一定条件下,该解答可退化为碎石桩复合地基固结解或竖井地基固结解,表明该解答的普适性及正确性。将该解答应用于工程实例及室内模型试验的沉降计算,计算结果与实测值吻合较好。开展大量计算研究此类复合地基不同工况下的固结性状,结果表明:在碎石桩桩间打设排水板,能有效提高复合地基固结速率,复合地基固结速率随排水板数量增加而加快;排水板渗透系数对复合地基固结速率及沉降速率的影响较大;与传统复合地基技术相比,碎石桩桩间增设排水板的工法具有更好的经济价值。 展开更多
关键词 碎石桩 排水板 组合型复合地基 固结 解析解 双向渗流
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不同葡萄砧木抗寒抗抽干能力比较研究
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作者 马晓燕 胡宏远 +3 位作者 李金洋 侯晨阳 李栋梅 王振平 《山西农业大学学报(自然科学版)》 CAS 北大核心 2024年第2期41-51,共11页
[目的]气候变化新形势下,进一步筛选适宜西北地区抗寒、抗抽干葡萄砧木品种,可为葡萄免埋土栽培推广提供理论依据和技术支撑。[方法]本文以41Bmgt、Riparia、420Bmgt、101-14、196-17、44-53ma、110R、Rupestris du Lot、SO4、161-490、... [目的]气候变化新形势下,进一步筛选适宜西北地区抗寒、抗抽干葡萄砧木品种,可为葡萄免埋土栽培推广提供理论依据和技术支撑。[方法]本文以41Bmgt、Riparia、420Bmgt、101-14、196-17、44-53ma、110R、Rupestris du Lot、SO4、161-490、1103P、5BB、3309、Leon Millt共14种13年生葡萄砧木为试材,通过测定离体一年生枝条累计失水速率,结合田间调查葡萄砧木存活率和离体一年生枝条抽干率,以此来评价不同葡萄砧木品种抗抽干能力;结合前人研究及砧木品种特性,采用高低温交变试验箱模拟低温的方法,设置4(对照)、-15、-20、-25和-30℃一系列温度梯度水平,测定不同葡萄砧木一年生枝条相对电导率、丙二醛、游离脯氨酸、可溶性糖及可溶性蛋白5个生理生化指标,利用隶属函数法进行综合评价不同葡萄砧木的抗寒性。[结果]不同葡萄砧木的抗抽干能力由强到弱依次为:3309>161-490>196-17>Leon Millt>420Bmgt>44-53ma>Riparia>110R>1103P>SO4>101-14>41Bmgt>5BB>Rupestris du Lot;随着处理温度的降低,不同葡萄砧木枝条的抗寒指标总体呈现上升趋势,但不同品种之间存在差异。根据隶属函数的综合分析,结果显示各葡萄砧木的抗寒性由强到弱依次为:SO4>196-17>Leon Millt>5BB>Riparia>44-53ma>420Bmgt>1103P>3309>110R>Rupestris du Lot>101-14>41Bmgt>161-490。[结论]Riparia、196-17、44-53ma和Leon Millt具有较强的抗抽干能力和抗寒性,可作为我国西北地区免埋土葡萄砧木使用。 展开更多
关键词 葡萄砧木 高低温交变试验箱 抗寒性 抗抽干 隶属函数法
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