Jet formation and penetration performance of a double-layer charge liner with chemically-deposited tungsten as the inner liner

This paper proposes a type of double-layer charge liner fabricated using chemical vapor deposition(CVD)that has tungsten as its inner liner.The feasibility of this design was evaluated through penetration tests.Double-layer charge liners were fabricated by using CVD to deposit tungsten layers on the inner surfaces of pure T2 copper liners.The microstructures of the tungsten layers were analyzed using a scanning electron microscope(SEM).The feasibility analysis was carried out by pulsed X-rays,slug-retrieval test and static penetration tests.The shaped charge jet forming and penetration law of inner tungsten-coated double-layer liner were studied by numerical simulation method.The results showed that the double-layer liners could form well-shaped jets.The errors between the X-ray test results and the numerical results were within 11.07%.A slug-retrieval test was found that the retrieved slug was similar to a numerically simulated slug.Compared with the traditional pure copper shaped charge jet,the penetration depth of the double-layer shaped charge liner increased by 11.4% and>10.8% respectively.In summary,the test results are good,and the numerical simulation is in good agreement with the test,which verified the feasibility of using the CVD method to fabricate double-layer charge liners with a high-density and high-strength refractory metal as the inner liner.

Discovery and Significance of the Triassic–Late Paleozoic Double-layered Basement in the Songliao Basin:Based on the Complete Coring Data from ICDP Borehole SK2

The Songliao Basin(SLB)covers an area of approximately 260,000 km2in northeastern Asia and preserves a continuous and complete Cretaceous terrestrial record(Wang et al.,2021).The region is the most important petroliferous sedimentary basin in China because of its continual annual oil and gas equivalent production of tens of millions of tons(ca.220–440 million barrels per year)since 1959.The SLB was previously thought to have developed on Hercynian basement and accumulated continuous sedimentary deposits during the Late Jurassic and Cretaceous(Wan et al.,2013;Wang et al.,2016).

Performance and Application of Double-layered Microcapsule Corrosion Inhibitors

Double-layered microcapsule corrosion inhibitors were developed by sodium monofluorophosphate as the core material,polymethyl methacrylate as the inner wall material,and polyvinyl alcohol as the outer wall material combining the solvent evaporation method and spray drying method.The protection by the outer capsule wall was used to prolong the service life of the corrosion inhibitor.The dispersion,encapsulation,thermal stability of microcapsules,and the degradation rate of capsule wall in concrete pore solution were analyzed by ultra-deep field microscopy,scanning electron microscopy,thermal analyzer,and sodium ion release rate analysis.The microcapsules were incorporated into mortar samples containing steel reinforcement,and the effects of double-layered microcapsule corrosion inhibitors on the performance of the cement matrix and the actual corrosion-inhibiting effect were analyzed.The experimental results show that the double-layered microcapsules have a moderate particle size and uniform distribution,and the capsules were completely wrapped.The microcapsules as a whole have good thermal stability below 230 ℃.The monolayer membrane structure microcapsules completely broke within 1 day in the simulated concrete pore solution,and the double-layer membrane structure prolonged the service life of the microcapsules to 80 days in the simulated concrete pore solution before the core material was completely released.The mortar samples containing steel reinforcement incorporated with the double-layered microcapsule corrosion inhibitors still maintained a higher corrosion potential than the monolayer microcapsule corrosion inhibitors control group at 60 days.The incorporation of double-layered microcapsules into the cement matrix has no significant adverse effect on the setting time and early strength.

康复护理在外固定架联合VSD技术治疗胫腓骨开放性骨折中的应用效果

探讨康复护理在外固定架联合VSD技术治疗胫腓骨开放性骨折中的应用效果。方法 筛选2019年9月~2024年9月我院接受外固定架联合VSD技术治疗的40例胫腓骨开放性骨折患者,以采用常规护理作为对照组(20例),以采用康复护理作为观察组(20例),对比两组临床护理效果、并发症发生情况。结果 观察组患者临床护理总有效率相较对照组有可观上升,有差异(P<0.05);观察组关节僵硬、患肢短缩等并发症总发生率相较对照组有明显下降(P<0.05)。结论 在临床实践中,针对胫腓骨开放性骨折的治疗,外固定架与VSD技术的联合运用已成为一种颇受欢迎的方法,当康复护理与外固定架及VSD技术相结合时,患者所展现出的护理效果尤为显著,不仅减少了并发症的出现,还大大加速患肢功能的恢复进程,更彰显了康复护理在这一领域中的独特价值。

Double-layer model updating for steel-concrete composite beam cable-stayed bridge based on GPS

In order to establish the relationship between the measured dynamic response and the health status of long-span bridges, a double-layer model updating method for steel-concrete composite beam cable-stayed bridges is proposed. Measured frequencies are selected as the first-layer reference data, and the mass of the bridge deck, the grid density, the modulus of concrete and the ballast on the side span are modified by using a manual tuning technique. Measured global positioning system （GPS） data is selected as the second-layer reference data, and the degradation of the integral structure stiffness EI of the whole bridge is taken into account for the second-layer model updating by using the finite element iteration algorithm. The Nanpu Bridge in Shanghai is taken as a case to verify the applicability of the proposed model updating method. After the first-layer model updating, the standard deviation of modal frequencies is smaller than 7%. After the second-layer model updating, the error of the deflection of the mid-span is smaller than 10%. The integral structure stiffness of the whole bridge decreases about 20%. The research results show a good agreement between the calculated response and the measured response.

基于VSD模型的乐清湾生态系统脆弱性评价

为探明海湾生态系统脆弱性及主要影响因素,以乐清湾生态系统为研究对象,基于“暴露程度、敏感性和适应能力”的VSD(vulnerability scoping diagram)模型,应用层次分析和模糊综合评价法定量评价了2010—2012、2015—2017、2020—2022年乐清湾生态系统脆弱性状况。结果表明,乐清湾生态系统在3个阶段均处于“中度脆弱”水平,综合得分逐渐降低,呈逐步改善趋势。3个阶段中,暴露程度总体变化不大,敏感性逐步改善,适应能力逐步提升,主要人为胁迫因子为工业产值占GDP比例、滩涂围垦面积占海湾面积比例和海水养殖密度,主要敏感因子为生物量、生物多样性综合指数和水生境综合指数。为提升乐清湾生态系统健康水平,应优化产业布局、调整海水养殖结构、加强海岸带综合整治修复、推进生物多样性保护专项立法、加大生态监管力度和提高公民参与程度。

VSD治疗对胫骨骨折术后继发骨感染患者手术指标、炎性因子及功能恢复的影响

目的探讨负压封闭引流技术(VSD)治疗对胫骨骨折术后继发骨感染患者手术指标、炎性因子、功能恢复的影响。方法选取2020年12月至2022年6月河北医科大学第三医院收治的87例胫骨骨折内固定术后继发骨感染患者,均为胫骨干骨折;其中原开放骨折55例,一期均缝合伤口;32例在外伤发生时一期清创后行内固定手术;对患者采用手术清创、去除内固定物,行外固定架固定,经清创后局部均存在创面不能完全闭合,合并骨外露,随机选用VSD覆盖治疗(研究组,n=46)或骨水泥覆盖治疗(对照组,n=41),分析患者病原菌构成分布、比较两组手术指标、炎症因子[肿瘤坏死因子-α(TNF-α)、白介素-6(IL-6)、C反应蛋白(CRP)水平]、功能恢复情况[膝关节、踝关节功能以及肢体功能恢复情况]以及并发症情况。结果87例患者共87株病原菌,其中革兰阳性菌43株(49.42%),革兰阴性菌32株(36.78%),真菌12株(13.80%)。研究组换药次数少于对照组,控制感染时间、创面无菌时长、住院时间、行皮瓣转移手术时间均短于对照组,差异均有统计学意义(P<0.05);治疗后两组TNF-α、IL-6、CRP水平均下降,其中研究组变化最为显著,差异有统计学意义(P<0.05);治疗后两组HSS、Baird-Jackson评分均上升,其中研究组变化最为显著,差异有统计学意义(P<0.05)。研究组优良率为(95.65%)高于对照组优良率(80.49%),差异有统计学意义(P<0.05)。结论在创面不能闭合情况下,VSD治疗胫骨骨折内固定术后继发骨感染患者,可改善患者手术指标、炎性因子水平,促进患者肢体功能恢复,值得临床推广应用。

Computation of the Fatigue Life of Road Wheel with Double-Layer Rubber Flange

In order to increase the fatigue life (FL) of road wheels (RW), a kind of double layer rubber flange (DLRF) is put forward. It consists of two layers of rubber, where metal wires are laid in the inner layer and the outer layer has no inlaid metal wires. Stress, strain and temperature field of DLRF were calculated with ANSYS finite element analysis (FEA) software, FL of DLRF RW was also computed with fracture mechanics fatigue theory. The results of computation indicate that the heat generated in RW's rubber flange (RF) can be reduced by the use of DLRF, and the FL of RW can be increased without affecting the mechanical intensity of RW.

基于VSD模型的陕南城市群水资源脆弱性评价及影响因子研究

[目的]构建基于社会-经济-生态耦合作用下的陕南城市群水资源脆弱性模型,阐明水资源脆弱性状态,厘定影响因子,助力秦岭地区人水和谐。[方法]基于暴露度-敏感性-适应性(Vulnerability Scoping Diagram,VSD)对陕南城市群水资源脆弱性进行了评价,结合多元统计法,进一步识别了社会-经济-生态耦合作用下水资源脆弱性的影响因子。[结果]2011—2020年,陕南整体水资源脆弱性的变化趋势与商洛市最相似,除2011年极度脆弱外,基本保持在轻度脆弱状态,而汉中市和安康市的水资源脆弱性等级较高,水安全保障程度相对较低;陕南城市群水资源脆弱性的主控因子有生态环境用水量、人均水资源量、年降水量;优化生态环境用水量分配,加强对年降水量与人均水资源量监测,将成为陕南城市群降低水资源脆弱性新的工作重心。[结论]陕南城市群水资源系统安全性的提升与当地注重水生态文明建设以及与社会-经济协调发展有关。此外,构建的VSD模型适用于陕南城市群水资源脆弱性评价,可为缓解人-城-水矛盾提供理论指导。

AO流速/VSD处流速、LVEF/三尖瓣反流流速在室间隔缺损患儿术前的检测意义分析

目的探讨主动脉(AO)流速/室间隔缺损(VSD)处流速、左室射血分数(LVEF)/三尖瓣反流流速在室间隔缺损患儿术前的检测意义。方法回顾性选取2021年1月至2023年5月期间于本院接受手术治疗的81例室间隔缺损患儿的临床资料,所有患儿术前均接受超声心动图检查,收集相关检测结果(包括AO流速/VSD处流速、LVEF/三尖瓣反流流速等),统计术后并发症发生情况,根据有无术后并发症分组,进行单因素及多因素分析,建立Logistics回归模型,总结影响患儿预后的风险因素;通过ROC曲线分析,评估AO流速/VSD处流速、LVEF/三尖瓣反流流速对室间隔缺损患儿预后风险的预测价值。结果81例患儿中存在术后并发症有9例,发生率11.11%,经单因素及多因素分析,有并发症组与无并发症组缺损直径、手术时间、气管插管时间、手术类型、NYHA分级、AO流速/VSD处流速、LVEF/三尖瓣反流流速差异有统计学意义,且均为术后并发症独立影响因素(P<0.05);经ROC曲线分析,AO流速/VSD处流速、LVEF/三尖瓣反流流速对室间隔缺损患儿预后的敏感度、特异度均较高,具有一定预测价值(P<0.05)。结论影响室间隔缺损患儿术后并发症的风险因素较多,其中AO流速/VSD处流速、LVEF/三尖瓣反流流速两种指标组合对手术后风险具有较好的预测价值,可作为临床参考指标,对室间隔患儿的预后风险评估具有较高参考价值,推荐临床广泛应用,具有较好学术价值。

Double-layered osmotic pump controlled release tablets of actarit: In vitro and in vivo evaluation

The aim of the study was to develop actarit double-layered osmotic pump tablets to overcome the weak points of actarit common tablets, such as short half-life and large plasma concentration fluctuations. Single factor experiment and orthogonal test were applied to optimize the formulation;the pharmacokinetic study was performed in beagle dogs adopting actarit common tablets as reference tablets. The optimal formulation was as follows: drug layer: 150 mg actarit, 240 mg PEO-N80, 50 mg NaCl;push layer: 140 mg PEO-WSR303, 20 mg NaCl;coating solution: 30 g cellulose acetate and 6 g PEG 4000 in 1000 ml 94% acetone solution, 60 mg coating weight gain. The pharmacokinetic study showed that T max was prolonged by the contrast of commercial common tablets with constant drug release rate, but the bioavailability was equivalent. And a good in vivo –in vitro correlation of the actarit osmotic pump tablets was also established. The designed actarit osmotic pump tablets can be applied for rheumatoid arthritis, proposing a promising replacement for the marked common products.

Double-layered covered stent for the treatment of malignant oesophageal obstructions: Systematic review and meta-analysis

AIM To investigate the efficacy of double-layered covered stent in the treatment of malignant oesophageal obstructions.METHODS A systematic review and meta-analysis was performed following the PRISMA process. Pub Med(Medline),EMBASE(Excerpta Medical Database),AMED(Allied and Complementary medicine Database),Scopus and online content,were searched for studies reporting on the Ni Ti-S polyurethane-covered double oesophageal stent for the treatment of malignant dysphagia. Weighted pooled outcomes were synthesized with a random effects model to account for clinical heterogeneity. All studies reporting the outcome of palliative management of dysphagia due to histologically confirmed malignant oesophageal obstruction using double-layered covered nitinol stent were included. The level of statistical significance was set at α = 0.05.RESULTS Six clinical studies comprising 250 patients in total were identified. Pooled technical success of stent insertion was 97.2%(95%CI: 94.8%-98.9%; I2 = 5.8%). Pooled complication rate was 27.6%(95%CI: 20.7%-35.2%; I2 = 41.9%). Weighted improvement of dysphagia on a scale of 0-5 scoring system was-2.00 [95%CI:-2.29%-(-1.72%); I2 = 87%]. Distal stent migration was documented in 10 out of the 250 cases examined.Pooled stent migration rate was 4.7%(95%CI: 2.5%-7.7%; I2 = 0%). Finally,tumour overgrowth was reported in 34 out of the 250 cases with pooled rate of tumour overgrowth of 11.2%(95%CI: 3.7%-22.1%; I2 = 82.2%). No funnel plot asymmetry to suggest publication bias(bias = 0.39,P = 0.78). In the sensitivity analysis all results were largely similar between the fixed and random effects models.CONCLUSION The double-layered nitinol stent provides immediate relief of malignant dysphagia with low rates of stent migration and tumour

One-dimensional consolidation of double-layered soil with non-Darcian flow described by exponent and threshold gradient

Based on non-Darcian flow law described by exponent and threshold gradient within a double-layered soil, the classic theory of one-dimensional consolidation of double-layered soil was modified to consider the change of vertical total stress with depth and time together. Because of the complexity of governing equations, the numerical solutions were obtained in detail by finite difference method. Then, the numerical solutions were compared with the analytical solutions in condition that non-Darcian flow law was degenerated to Dary's law, and the comparison results show that numerical solutions are reliable. Finally, consolidation behavior of double-layered soil with different parameters was analyzed, and the results show that the consolidation rate of double-layered soil decreases with increasing the value of exponent and threshold of non-Darcian flow, and the exponent and threshold gradient of the first soil layer greatly influence the consolidation rate of double-layered soil. The larger the ratio of the equivalent water head of external load to the total thickness of double-layered soil, the larger the rate of the consolidation, and the similitude relationship in classical consolidation theory of double-layered soil is not satisfied. The other consolidation behavior of double-layered soil with non-Darcian flow is the same as that with Darcy's law.

Analysis on Connectivity of Inter-Orbit-Links in a MEO/LEO Double-Layer Satellite Network

As an important scheme of future global mobile satellite communication systems to provide multimedia service, a Double-Layer Satellite Network （DLSN） with MEO satellites and LEO satellites is proposed. The Inter-Orbit-Links （IOLs） between layers is an essential factor, which affects the performances of the DLSN systems. Considering certain constellation parameters, the geometric characteristics of IOLs are described and the connectivity of MEO satellites and LEO satellites in the DLSN is analyzed. By computer simulation, the results show that IOLs should be selectively established according to certain parameters rather than the simple in-sight principle.

Numerical investigation of velocity distribution of turbulent flow through vertically double-layered vegetation

The velocity structures of flow through vertically double-layered vegetation(VDLV)as well as single-layered rigid vegetation(SLV)were investigated computationally with a three-dimensional(3D)Reynolds stress turbulence model,using the computational fluid dynamics(CFD)code FLUENT.The detailed velocity distribution was explored with a varying initial Froude number(Fr),with consideration of the steady subcritical flow conditions of an inland tsunami.In VDLV flows,the numerical model successfully captured the inflection point in the profiles of mean streamwise velocities in the mixing-layer region around the top of short submerged vegetation.An upward and downward movement of flow occurred at the positions located just behind the tall and short vegetation,respectively.Overall,higher streamwise velocities were observed in the upper vegetation layer due to high porosity,with Pr=98%(sparse vegetation,where Pr is the porosity),as compared to those in the lower vegetation layer,which had comparatively low porosity,with Pr=91%(dense vegetation).A rising trend of velocities was found as the flow passed through the vegetation region,followed by a clear sawtooth distribution,as compared to the regions just upstream and downstream of vegetation where the flow was almost uniform.In VDLV flows,a rising trend in the flow resistance was observed with the increase in the initial Froude number,i.e.,Fr?0.67,0.70,and 0.73.However,the flow resistance in the case of SLV was relatively very low.The numerical results also show the flow structures within the vicinity of short and tall vegetation,which are difficult to attain through experimental measurements.

Release test of alliin/alliinase double-layer tablet by HPLC-Allicin determination

A simple, precise and accurate method was developed and validated for the determination of allicin release from alliin/alliinase double-layer tablets. According to Appendix XC Ⅱ of Chinese Pharmacopoeia 2010 edition Volume II, a small glass-method was adopted at the rotational speed of 100 r/min using 100 mL phosphate buffer （pH 6.8） as release medium. The release amount was determined by HPLC with a C18 column （250 mm × 4.6 mm, 5 μm） using the mobile phase consisting of methanol -0.4% carboxylic acid （65：35） at a flow rate of 1 mL/min and UV detection at 242 nm. The current method demonstrates good linearity over the range 4.052- 405.2 μg/mL （r2=0.9999） with an average recovery of 105.5%（RSD= 1.25%）. The accumulative release of alliin/alliinase double-layer tablets had good homogeneity for withinand betweenbatches. The method established is simple, accurate and repeatable for the determination of allicin release from alliin/alliinase double-layer tablets.

Double-layer Bayesian Classifier Ensembles Based on Frequent Itemsets

Numerous models have been proposed to reduce the classification error of Naive Bayes by weakening its attribute independence assumption and some have demonstrated remarkable error performance. Considering that ensemble learning is an effective method of reducing the classifmation error of the classifier, this paper proposes a double-layer Bayesian classifier ensembles （DLBCE） algorithm based on frequent itemsets. DLBCE constructs a double-layer Bayesian classifier （DLBC） for each frequent itemset the new instance contained and finally ensembles all the classifiers by assigning different weight to different classifier according to the conditional mutual information. The experimental results show that the proposed algorithm outperforms other outstanding algorithms.

Empirical formulae for electric double-layer repulsion between two arbitrarily inclined clay particles

To understand the mesoscopic mechanism of clayey soil in view of macroscopic behavior, it is essential to quantitatively calculate the electric double-layer repulsion between arbitrarily inclined clay particles.However, suitable calculation methods with high efficiency and accuracy are still rare at present in literature. Based on a great number of numerical calculations of the repulsion between two inclined platy clay particles, explicit empirical formulae for estimating electric double-layer repulsion between clay particles are put forward. Comparison between the empirical solutions and corresponding numerical results shows that the proposed formulae have a reasonable accuracy, and application of the presented formula is easy and efficient.

Numerical simulation on thixo-co-extrusion of double-layer tube with A356/AZ91D

Based on analysis of the main forming methods for double-layer tube,a new short-term forming process called thixo-co-extrusion was put forward in producing double-layer tube by combining the semi-solid forming technology and multi-billet extrusion technology.By means of forward extrusion with shaft,a finite element model of thixo-co-extrusion with A356/AZ91 was constructed by ABAQUS FEM software.The distributions of temperature field and velocity field as well as the contact force during thixo-co-extrusion were studied.The diffusion on the interfaces between inner and outer metals was analyzed.The simulation results show that,in the beginning of thixo-co-extrusion,the uneven wall thickness can appear.To thickness ratio of 5:5,a double layer tube with good inner and outer wall combination can be realized if VA356 is 0.12 m/s and VAZ91 is 0.20 m/s.

Analysis of one-dimensional rheological consolidation of double-layered soil with fractional derivative Merchant model and non-Darcian flow described by non-Newtonian index

To further investigate the one-dimensional(1D)rheological consolidation mechanism of double-layered soil,the fractional derivative Merchant model(FDMM)and the non-Darcian flow model with the non-Newtonian index are respectively introduced to describe the deformation of viscoelastic soil and the flow of pore water in the process of consolidation.Accordingly,an 1D rheological consolidation equation of double-layered soil is obtained,and its numerical analysis is performed by the implicit finite difference method.In order to verify its validity,the numerical solutions by the present method for some simplified cases are compared with the results in the related literature.Then,the influence of the revelent parameters on the rheological consolidation of double-layered soil are investigated.Numerical results indicate that the parameters of non-Darcian flow and FDMM of the first soil layer greatly influence the consolidation rate of double-layered soil.As the decrease of relative compressibility or the increase of relative permeability between the lower soil and the upper soil,the dissipation rate of excess pore water pressure and the settlement rate of the ground will be accelerated.Increasing the relative thickness of soil layer with high permeability or low compressibility will also accelerate the consolidation rate of double-layered soil.