Fracture evolution characteristics of sandstone containing double fissures and a single circular hole under uniaxial compression

The uniaxial compression experiments on the sandstone samples containing double fissures and a single circular hole were carried out by using electro-hydraulic servo universal testing machine to investigate the effect of rock bridge angle β and fissure angle α on mechanical properties and evolution characteristics of cracks.The results show that the peak strength,peak strain and elastic modulus of defected specimens decrease comparing with those for intact sample,and show a decreased trend firstly and then increase with β changing from 0° to 90°.The peak strength and elastic modulus achieve the minimum value as the rock bridge angle is 60°,while the peak strain reaches the minimum value with the rock bridge angle of 45°.The crack initiation of tested rock samples occurs firstly in stress concentration areas at tips of prefabricated fissures under uniaxial compression,and then propagates constantly and coalescences with the prefabricated hole.Some secondary cracks initiate and propagate as well until buckling failure happens.The rock bridge angle has a great influence on crack initiation,coalescence,final failure mode,crack initiation stress and transfixion stress.The peak strength varies significantly,while the elastic modulus and peak strain change slightly,and the failure modes are also different due to the influence of fissure angle.

Experimental Study on a Single Layer Two-Way Grid Shell with Tension Members

Single layer two-way grid shell with in-plane and out-of-plane tension members is a new type of single-layer latticed shell roofs. Compared with traditional single-layer latticed shells,this new type has a unique mesh form and excellent rigidity. In order to further understand the buckling behaviors of single layer two-way grid cylindrical shell roof with tension members,the buckling experiments have been undertaken to investigate the effect of tension members,in either out-of-plane or in-plane placement. A single layer two-way grid cylindrical shell roof with out-of-plane tension members has been tested under symmetric and asymmetric loading. The tension member placement,the introducing initial axial force to tension members and the load patterns are considered to investigate the buckling behavior. Experimental results indicate that four long out-ofplane tension members work well under symmetrical loading,but only two long out-of-plane tension members work under asymmetrical loading. It can be concluded that the PC bar members used as tension members for this study are useful in the construction of a single layer two-way grid cylindrical shell roof with structural members intersecting at small angles.

Efficacy of Single Burr Hole in Management of Chronic Subdural Hematoma

Background: Surgery of chronic subdural hematoma (CSDH) is a common practice of neurosurgeons. CSDH is considered a pathology of the elderly and usually many co-morbidities are present. CSDH carries high risk of mortality if not treated or not treated well. So, the minimal, safe and adequate surgical intervention is the bases to choose specific surgical maneuver. Aim of the Study: The efficacy of a single burr in evacuation and treatment of chronic subdural hematoma. Methods: This study was held in Assiut university hospitals, neurosurgical department. It is a prospective randomized controlled study. 113 patients were enrolled in this study in the period between March 2018 and June 2019. We included all cases of chronic subdural hematoma (CSDH) and subacute subdural hematoma that were evacuated with single burr hole. Hematomas either, unilateral or bilateral were included. Septated hematomas were excluded. Patients’ clinical characteristics as age, sex, clinical presentation, co-morbidities and patients outcome were recorded. Postoperative status as regards improvement of the neurological status, complications and recurrence of hematoma were recorded. Results: We had 113 patients operated via properly situated single burr hole in our study. 113 patients were included in this study, 79 males (69.9%) and 34 females (30.1%). Age of the patients ranges between 27 years old and 90 years old. Postoperative follow up was evaluated according to Glasgow outcome score (GOS). We had 98 patients with good recovery, 4 patients with moderate disability, 6 patients with severe disability and 5 patients died. Complications were in form of 3 patients with residual hematoma, 2 patients with tension pneumocephalus, 7 patients developed postoperative seizure, 5 cases developed cortical/parenchymal hematoma and 9 cases developed hematoma recurrence. Conclusion: Single, properly situated burr hole with previously described characters is an effective treatment option in cases of CSDH. It helps adequate, effective and safe removal of the pathology with limited maneuver.

Single crystal growth and electronic structure of Rh-doped Sr_(3)Ir_(2)O_(7)

Ruddlesden-Popper iridate Sr_(3)Ir_(2)O_(7)is a spin-orbit coupled Mott insulator.Hole doped Sr_(3)Ir_(2)O_(7)provides an ideal platform to study the exotic quantum phenomena that occur near the metal-insulator transition(MIT)region.Rh substitution of Ir is an effective method to induce hole doping into Sr_(3)Ir_(2)O_(7).However,the highest doping level reported in Sr_(3)(Ir_(1-x)Rh_(x))_(2)O_(7)single crystals was only around 3%,which is far from the MIT region.In this paper,we report the successful growth of single crystals of Sr3(Ir_(1-x)Rh_(x))_(2)O_(7)with a doping level of~9%.The samples have been fully characterized,demonstrating the high quality of the single crystals.Transport measurements have been carried out,confirming the tendency of MIT in these samples.The electronic structure has also been examined by angle-resolved photoemission spectroscopy(ARPES)measurements.Our results establish a platform to investigate the heavily hole doped Sr_(3)Ir_(2)O_(7) compound,which also provide new insights into the MIT with hole doping in this material system.

Preparation of Silica–Alumina Hollow Spheres with a Single Surface Hole by Co-axial Microchannel

Si/Al composite hollow spheres with a surface hole were prepared with the co-axial microchannel in a one-step method. It is easy to use the technique for size control and continuous operation. At Si/Al ratio between 4 and 5, a hole forms on the surface, due to the fast gelation process and high viscosity of the sol. Scanning electron microscopy, nitrogen adsorption–desorption isotherms, and mercury intrusion method are used to characterize the samples. The hole size is 40–150 μm and the particle size is 450–600 μm. The size can be adjusted by the flow rate of the oil phase.

Single-mode low threshold current multi-hole vertical-cavity surface-emitting lasers

A multi-hole vertical-cavity surface-emitting laser （VCSEL） operating in stable single mode with a low threshold current was produced by introducing multi-leaf scallop holes on the top distributed Bragg-refleetor of an oxidation- confined 850 nm VCSEL. The single-mode output power of 2.6 mW, threshold current of 0.6 mA, full width of half maximum lasing spectrum of less than 0.1 nm, side mode suppression ratio of 28.4 dB, and far-field divergence angle of about 10% are obtained. The effects of different hole depths on the optical characteristics are simulated and analysed, including far-field divergence, spectrum and lateral cavity mode. The single-mode performance of this multi-hole device is attributed to the large radiation loss from the inter hole spacing and the scattering loss at the bottom of the holes, particularly for higher order modes.

Single neutron hole entropy in ^(105)Cd and ^(111)Cd

The nuclear level density and entropy were calculated for105 Cd,106Cd,111 Cd and112Cd based on the Back Shifted Fermi Gas(BSFG) model and the Constant Temperature(CT) model. Then, the entropies were extracted in the microcanonical ensemble according to recent experimental data on nuclear level density measured by the Oslo group for these nuclei and are compared with their corresponding macroscopic calculations. Entropies of the neutron hole were estimated from the entropy difference between the odd-mass and even-even nuclei. The results reveal that the CT model describes better the extracted microcanonical results.

后路单开门钉板固定结合Key-hole技术在混合型颈椎病患者中的应用效果

目的:分析后路单开门钉板固定结合Key-hole技术在混合型颈椎病患者中的应用效果。方法:采用前瞻性分析法,以随机数表法将2021年6月至2023年6月濮阳市人民医院120例混合型颈椎病患者分为对照组和观察组,各60例。对照组患者采用后路单开门钉板固定治疗,观察组患者采用后路单开门钉板固定结合Key-hole技术治疗。对两组患者术前和术后3个月的JOA评分、JOA评分改善率、Cobb角、ROM、颈椎肌张力及术后3个月的并发症情况进行比较。结果:与对照组相比,术后观察组的JOA评分、JOA评分改善率均升高,术后观察组的Cobb角、ROM、颈椎肌张力均升高,术后3个月观察组的神经根症状总有效率升高,术后3个月内观察组的并发症总发生率降低,差异有统计学意义(P<0.05)。结论:后路单开门钉板固定结合Key-hole技术能够有效缓解混合型颈椎病患者的颈髓、神经根压迫,改善颈髓、神经根功能,且可减少并发症发生。

镍基单晶高温合金近服役环境性能研究进展

航空发动机与燃气轮机作为国之重器,对保障国防安全和能源安全具有重要意义。随着发动机效率的不断提升,涡轮进气口温度不断提高。先进叶片往往采用高代次单晶高温合金材料制备,具有薄壁、多孔复杂冷却结构,且表面涂覆先进涂层,因而先进单晶叶片结构越来越精细复杂,服役过程中叶片不同部位温度场、应力场分布变化更大,其损伤机制无法通过传统棒状试样的变形损伤机制完全体现。基于先进单晶叶片的结构特点及服役环境特点,综述了叶片结构(薄壁、气膜孔)、二次枝晶取向(二次取向)及先进涂层等单一因素及多因素耦合作用对单晶合金拉伸、蠕变及疲劳等典型性能的影响规律及损伤机理研究,并对镍基单晶高温合金近服役环境性能研究的发展方向进行展望。

单操作孔电视胸腔镜肺癌根治术治疗非小细胞肺癌患者的疗效观察

目的观察单操作孔电视胸腔镜(VATS)肺癌根治术对非小细胞肺癌(NSCLC)血管内皮生长因子受体2(VEGFR2)、胸苷激酶1(TK1)水平的影响。方法我院收治的245例NSCLC患者,按手术方式分为对照组(三孔胸腔镜肺癌根治术,n=115)和观察组(单操作孔VATS肺癌根治术,n=130),比较两组围术期指标、视觉模拟(VAS)评分、肺功能、炎性因子、肿瘤标志物、VEGFR2、TK1水平及并发症。结果观察组术中出血量较对照组少(P<0.05);术后,观察组VAS评分、炎性因子、肿瘤标志物和VEGFR2、TK1水平低于对照组,肺功能高于对照组(P<0.05)。结论单操作孔VATS肺癌根治术治疗NSCLC出血量少、疼痛轻,可改善肺功能,降低炎性因子、肿瘤标志物和VEGFR2、TK1水平,且不增加术后并发症,值得临床推广。

单针振动气力式辣椒精量排种器设计与试验

【目的】育苗移栽是辣椒种植普遍采用的方式,针对辣椒穴盘育苗播种环节存在的漏播现象,设计了一种用于漏播补种的单针振动气力式辣椒精量排种器,用于对穴盘中的空穴进行补种,从而提高生产效率。【方法】以“兴蔬皱辣2号”辣椒种子为研究对象,结合种子物理特性测定,对排种器振动供种机构、直线携种机构和控制系统进行分析和设计,并搭建了试验台。以种箱振动频率、气吸针真空度和气吸针直径为试验因素,以排种单粒率为试验评价指标,进行排种器单因素试验,确定种箱振动频率、气吸针真空度和气吸针直径具体取值范围分别为77~89 Hz、15~35 kPa和0.6~0.8 mm。在此基础上进行响应面试验,运用Design-Expert软件对试验数据进行方差分析、响应曲面分析和试验因素优化求解。【结果】确定了排种单粒率影响因素由大到小为气吸针真空度、气吸针直径和种箱振动频率,得出排种器最优作业参数为气吸针真空度27 kPa、气吸嘴直径0.7 mm、种箱振动频率85 Hz,样机试验排种单粒率为98.25%。【结论】该单针振动气力式辣椒精量排种器工作稳定,排种单粒率高,满足辣椒精量播种作业要求。

类抛物线形单孔悬挂芯光纤光镊设计与微粒操控

为提高光镊系统中光纤波导耦合度与微通道集成度,实现对微粒的多样操控,提出了一种类抛物线形单孔悬挂芯光纤光镊结构,从双光束聚焦光场机制出发,分析并建立了光镊探针尖端横向和轴向光阱力数学模型,通过出射光场分布仿真模型的计算,探究了类抛物线形悬挂芯光纤中空孔直径、微粒尺寸与纤芯功率等参量对出射光场和光阱力的影响。结合悬挂芯光纤流道的气压控制,利用CO_(2)激光熔融工艺制备了光纤光镊探针,建立了针对直径2、5、10μm的聚苯乙烯微粒操控实验。研究为单孔悬挂芯光纤应用于光纤光镊实现微粒操控乃至输运提供了技术基础,也为光纤光镊提高集成度与灵活性提供了新的思路。

经脐无气腹单孔腔镜联合罗哌卡因局部浸润麻醉在妊娠合并卵巢肿瘤中的应用

目的:研究妊娠合并卵巢肿瘤患者应用经脐无气腹单孔腔镜联合罗哌卡因局部浸润麻醉的临床疗效及安全性。方法:28例妊娠患者合并卵巢肿瘤行经脐无气腹单孔腔镜手术,按随机数字表分2组,观察组16例采用腰麻联合缝皮前罗哌卡因浸润麻醉,对照组12例采用腰麻,比较两组孕妇术后首次下床时间、通气时间、术后住院天数,术后6 h无创血压、心率(HR)、呼吸频率(RR)、血氧饱和度(SpO2),Ramsay镇静评分、术后6、24、48 h静息和运动状态下的疼痛评分,SAS焦虑评分、术后并发症、患者满意度、恢复质量表QoR15。结果:两组比较,术后住院天数、Ramsay评分、RR、SpO2及并发症发生率差异无统计学意义(P>0.05);观察组下床时间、通气时间缩短,无创血压、HR、疼痛评分、焦虑评分低于对照组,患者满意度、QoR15评分优于对照组,差异有统计学意义(P<0.05)。结论:妊娠合并卵巢肿瘤患者应用经脐无气腹单孔腔镜联合罗哌卡因局部浸润麻醉,可以减轻术后疼痛,减少孕妇焦虑,临床效果良好,值得推广应用。

单孔胸腔镜肺楔形切除术对早期肺癌患者的疗效及对肺功能的影响

目的探讨单孔胸腔镜肺楔形切除术对早期肺癌患者的治疗效果及对肺功能的影响。方法选用120例早期肺癌患者为研究对象,随机分为两组(研究组、对照组各60例)。对照组采用解剖性肺段切除术,研究组采用单孔胸腔镜肺楔形切除术,比较两组治疗后手术相关指标、视觉模拟量表(VAS)评分、肺功能指标及并发症发生率。结果研究组术后住院时间、手术时间、术中出血量等手术指标均优于对照组(P<0.05);术后两组VAS评分均上涨(P<0.05),但研究组VAS评分较对照组明显降低(P<0.05);两组肺功能指标均发生显著变化(P<0.05),研究组FEV1、MVV、FVC水平较对照组明显升高(P<0.05);研究组肺感染、肺漏气、肺不张、呼吸衰竭等并发症的总发生率较对照组明显下降(P<0.05)。结论对早期肺癌患者采用单孔胸腔镜肺楔形切除术治疗,效果较为理想,创伤小,恢复快,对肺功能影响不严重,临床应用价值较高。

台阶单孔爆破振动预测模型研究

爆破振动具有随机性,振动波的强度和频率具有非平稳性,为了构建能够真实反映爆破振动波形特性的台阶单孔爆破振动预测模型,通过调制白噪声的过程确定模型的频率函数,用角频率的时变性来描述振动波形频率的非平稳性;通过对强度包络函数的筛选,选取Gamma函数来描述爆破振动波形强度的非平稳性;用高通滤波处理提高了预测模型在低频段的模拟精度.以预测模型与现场实测波形的时程频率一致为约束条件,阻尼比与不规则指数呈线性关系,确定模型的频率参数(η,ξ,γ),以现场实测波形累计能量为约束条件,确定模型的强度参数(I0,α,β),模型输出波形的峰值振速、主频分别与现场实测波形特征的较好吻合,证明了所构建预测模型的正确性和有效性.

声呐渗流测试技术之质疑

介绍了近年来新出现的用声呐法测试渗流速度和渗流方向这一技术的核心内容,包括测试装置、测试原理和计算方法等。从理论和实践上对其提出了4方面的质疑:测试原理的理论基础、渗流速度计算方法、渗流方向确定和流场畸变。通过理论分析、公式的推导和数据的可靠性分析后认为:声呐测试渗流的原理缺乏理论解释;计算渗流速度的公式反映的只是孔内垂向流速度,实际还是由测量误差产生的伪垂向流速度,且该公式本身就推导不成立;无论垂向流是向上流动或向下流动,探头上部的水声器发射的声波到达下部平面对称分布的6个水声器的时间在理论上是相等的,因而也无法通过合成法求得渗流方向,所提供的渗流方向实际是由指数级时间误差计算得到的伪流向;即声呐法无法获得渗流速度,包括水平向渗流速度和垂直向流动速度,也无法获得水平向渗流方向。

基于倾向评分匹配的经脐单孔与三孔腹腔镜胆囊切除术治疗急性胆囊炎的临床疗效对比

目的探讨基于倾向评分匹配的经脐单孔与三孔腹腔镜胆囊切除术治疗急性胆囊炎的临床疗效。方法2020年1月~2022年12月行腹腔镜胆囊切除术的急性胆囊炎病人106例,根据治疗方法不同分为两组,研究组64例,采用经脐单孔腹腔镜胆囊切除术,对照组42例,采用三孔腹腔镜胆囊切除术。比较两组病人手术相关指标、术后恢复情况及术后并发症情况。结果两组体质量指数(BMI)、胆囊B超检查结果比较,差异无统计学意义(P>0.05),研究组病人平均年龄大于对照组,差异有统计学意义(P<0.05)。将两组病人倾向评分匹配后的一般资料进行比较发现,两组性别、年龄、BMI、胆囊B超检查结果无明显差异(P>0.05)。研究组手术时间为(61.48±10.24)分钟,对照组为(40.42±8.35)分钟;研究组术后6小时、24小时的疼痛视觉模拟评分法(VAS)评分分别为(5.63±1.04)分和(3.42±0.65)分,对照组分别为(7.22±1.61)分和(5.48±1.02)分,差异有统计学意义(P<0.05);两组病人手术中的失血量比较,差异无统计学意义(P>0.05)。研究组的住院时间及肠胃功能恢复时间分别为(2.05±0.42)天和(33.46±4.30)小时,对照组分别为(3.95±1.02)天和(47.58±7.62)小时;研究组病人对切口瘢痕满意度评分为(4.58±0.42)分,对照组为(3.02±0.38)分,两组比较差异有统计学意义(P<0.05)。研究组并发症总发生率为2.78%,对照组为16.67%,两组比较差异有统计学意义(P<0.05)。结论经脐单孔腹腔镜胆囊切除术治疗急性胆囊炎的术后疼痛感较三孔腹腔镜胆囊切除术明显更低,住院时间及肠胃功能恢复时间更短,病人对切口瘢痕满意度的评分更高,同时术后并发症的总发生率更低。

陆相页岩油固井滑套单簇孔压裂技术与效果评价

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