The Singularities of Gravitational Fields of Static Thin Loop and Double Spheres Reveal the Impossibility of Singularity Black Holes

In the classical Newtonian mechanics, the gravity fields of static thin loop and double spheres are two simple but foundational problems. However, in the Einstein’s theory of gravity, they are not simple. In fact, we do not know their solutions up to now. Based on the coordinate transformations of the Kerr and the Kerr-Newman solutions of the Einstein’s equation of gravity field with axial symmetry, the gravity fields of static thin loop and double spheres are obtained. The results indicate that, no matter how much the mass and density are, there are singularities at the central point of thin loop and the contact point of double spheres. What is more, the singularities are completely exposed in vacuum. Space near the surfaces of thin loop and spheres are highly curved, although the gravity fields are very weak. These results are inconsistent with practical experience and completely impossible. By reasonable analogy, black holes with singularity in cosmology and astrophysics are something illusive. Caused by the mathematical description of curved space-time, they do not exist in real world actually. If there are black holes in the universe, they can only be the types of the Newtonian black holes without singularities, rather than the Einstein’s singularity black holes. In order to escape the puzzle of singularity thoroughly, the description of gravity should return to the traditional form of dynamics in flat space. The renormalization of gravity and the unified description of four basic interactions may be possible only based on the frame of flat space-time. Otherwise, theses problems can not be solved forever. Physicists should have a clear understanding about this problem.

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.

Displacement of surrounding rock in a deep circular hole considering double moduli and strength-stiffness degradation

The problem of cavity stability widely exists in deep underground engineering and energy exploitation.First,the stress field of the surrounding rock under the uniform stress field is deduced based on a post-peak strength drop model considering the rock’s characteristics of constant modulus and double moduli.Then,the orthogonal non-associative flow rule is used to establish the displacement of the surrounding rock under constant modulus and double moduli,respectively,considering the stiffness degradation and dilatancy effects in the plastic region and assuming that the elastic strain in the plastic region satisfies the elastic constitutive relationship.Finally,the evolution of the displacement in the surrounding rock is analyzed under the effects of the double modulus characteristics,the strength drop,the stiffness degradation,and the dilatancy.The results show that the displacement solutions of the surrounding rock under constant modulus and double moduli have a unified expression.The coefficients of the expression are related to the stress field of the original rock,the elastic constant of the surrounding rock,the strength parameters,and the dilatancy angle.The strength drop,the stiffness degradation,and the dilatancy effects all have effects on the displacement.The effects can be characterized by quantitative relationships.

Effects of electron correlation and the Breit interaction on one- and two-electron one-photon transitions in double K hole states of He-like ions(10 ≤ Z ≤ 47)

The x-ray energies and transition rates associated with single and double electron radiative transitions from the double K hole state 2s2p to the 1s2s and 1s^2 configurations of 11 selected He-like ions(10 ≤ Z ≤ 47) are calculated using the fully relativistic multi-configuration Dirac–Fock method(MCDF). An appropriate electron correlation model is constructed with the aid of the active space method, which allows the electron correlation effects to be studied efficiently. The contributions of the electron correlation and the Breit interaction to the transition properties are analyzed in detail. It is found that the two-electron one-photon(TEOP) transition is correlation sensitive. The Breit interaction and electron correlation both contribute significantly to the radiative transition properties of the double K hole state of the He-like ions. Good agreement between the present calculation and previous work is achieved. The calculated data will be helpful to future investigations on double K hole decay processes of He-like ions.

Study on characteristics of a double-conductible channel organic thin-film transistor with an ultra-thin hole-blocking layer

The properties of top-contact organic thin-film transistors （TC-OTFTs） using ultra-thin 2, 9-dimethyl-4, 7- diphenyl-1, 10-phenanthroline （BCP） as a hole-blocking interlayer have been improved significantly and a BCP interlayer was inserted into the middle of the pentacene active layer. This paper obtains a fire-new transport mode of an OTFT device with double-conductible channels. The accumulation and transfer of the hole carriers arc limited by the BCP interlayer in the vertical region of the channel. A huge amount of carriers is located not only at the interface between pentacene and the gate insulator, but also at the two interfaces of pentacene/BCP interlayer and pentacene/gate insulator, respectively. The results suggest that the BCP interlayer may be useful to adjust the hole accumulation and transfer, and can increase the hole mobility and output current of OTFTs. The TC-OTFTs with a BCP interlayer at VDS = --20 V showed excellent hole mobility μFE and threshold voltage VTH of 0.58 cm^2/（V-s） and -4.6 V, respectively.

Mechanism and practice of rock control in deep large span cut holes

Deep large span cut holes are difficult to stabilize. The 7801 cut hole in the Lu'an Wuyang Mine was used as this project's background. The main factors affecting large span cut hole stability are analyzed. Pre- stressed bolting theory was used to design a roof control method for a large span roadway. By reducing the span and applying equal strength coordinated supports the rock could be stabilized. The control prin- ciples and methods are given herein along with the analysis. A double micro arch cross section roadway is defined and its use in solving the current problem is described. Beam arch theory was used to build a model of the double micro arch cross section roadway. A support reverse force model for the arch foot intersection was also derived. A support method based upon reducing the width of the large span in the cut hole is presented. These results show that the reduced span of the roadway roof plus the use of cable anchors and single supports gives an effective way to control the large span cut hole. On site monitoring showed that the reduced span support from the double micro arch cross section roadway design had a significant effect. The roadway surface displacement was small and harmful deformation of the cut hole was effectively controlled. This will ensure its long term stability.

燃烧室百叶与双排孔冷气对透平端壁冷却性能影响研究

针对燃烧室与透平冷气掺混导致实际二次流发展及端壁冷却性能偏离设计值的问题,综合考虑燃烧室百叶冷气尾迹与双排孔射流,数值研究了多源冷气射流在燃烧室与透平交界区的掺混机制,分析了其对透平静叶端壁气膜冷却与流动特性的影响规律。研究结果表明:空腔涡卷吸大部分百叶冷气,并跨越双排孔冷气向下游发展,马蹄涡卷吸限制大部分双排孔冷气,并向空腔涡外侧发展;当双排孔冷气吹风比M_h=0.5,1.0较小时,马蹄涡导致冷气形成楔形高冷效区域,空腔涡的附着侧和分离侧分别产生了高、低冷效区,随着百叶冷气吹风比M_l的增加,空腔涡强度显著降低,导致位于楔形中心的分离侧冷却效率有所提升;当双排孔冷气吹风比M_h为1.5时,双排孔冷气部分跨越马蹄涡,静叶端壁可实现完全冷气覆盖,此时百叶冷气吹风比M_l从0.5增加到1.5,静叶端壁平均冷却效率可从0.4提升到0.63。该研究为考虑燃烧室与透平交界区实际流动掺混情况的静叶端壁冷却结构与布局设计提供理论基础。

高压气体双孔浸没射流振荡频率特性研究

在沸水堆或小型堆中一般将抑压水池作为气体排放的热阱以实现安全壳压力的有效控制。基于这一背景,本文在不同过冷度下对高压气体双孔浸没射流振荡主频特性进行了一系列实验研究,其中不凝性气体份额为0.0~0.4,孔间距范围为1.5 d~3 d。实验结果表明,无论是纯蒸汽还是混合气,在双孔射流时两股气羽均表现出向中间汇聚的形态,甚至汇聚到一起形成联合射流,相较单孔射流而言双孔射流气羽尺度增大冷凝时间延长,所以其振荡主频更低。分析射流参数影响发现,纯蒸汽射流振荡主频随过冷度和孔间距的增加而增加。同时本文总结振荡主频影响规律提出了纯蒸汽射流主频的预测关系式,预测精度在-15%~20%之间。混合气体射流时(纯蒸汽+不凝性气体)振荡主频随过冷度和孔间距的增加而增加,与纯蒸汽射流主频变化规律一致。值得注意的是,混合气射流相较纯蒸汽而言振荡主频更低,并且主频随不凝气份额增加而降低。

基于力柔顺控制的断路器轴孔零件装配算法

针对双臂机器人断路器轴孔零件装配操作任务,研究了一种两阶段轴孔装配轨迹规划策略,为了提高双臂协调装配作业的柔顺性和精确性,提出一种FAIC控制算法,实现精确的力跟踪。首先建立轴和孔接触状态力学模型,开展轴孔装配机理研究,根据双臂末端受力平衡,提出了一种操作空间轴孔装配的双臂运动轨迹规划方法。基于阻抗控制实现柔顺轴孔装配,采用模糊控制器在线辨识阻抗控制最优参数,提高装配操作质量。实验结果表明,在双臂协作轴孔装配策略结合FAIC算法作用下,轴孔间接触力控制在3 N以内,装配效率提高36.5%。综上所述,本文提出的FAIC算法与装配策略在双臂协同断路器装配作业中有效地缩短磁组件的装配时间,提高装配效率与精度。

基于BIM技术的浅埋双孔隧道地震响应规律研究

通过BIM软件Revit建立浅埋双孔隧道的信息模型,基于BIM信息模型,导入ABAQUS结构分析软件,基于无限元-有限元方法应用于浅埋双孔隧道进行力学行为分析的可行性和准确性,分析隧道衬砌的刚度和设置减震层对浅埋双孔隧道在典型地震波作用下的响应规律,找到适合该浅埋双孔隧道的减震层材料和厚度,为后续浅埋隧道地震响应规律的研究提供借鉴。

窄间隙双洞隧道锚施工期安全性能分析

目前针对隧道锚固悬索桥的极限承载能力的研究较多,但针对窄间隙双洞隧道锚悬索桥锚固隧道施工过程的稳定性和安全性的研究较少。为了分析隧道锚在窄间隙条件下施工过程的受力特点,采用FLAC3D对隧道施工过程的受力特性进行数值分析。研究表明,小川大桥的窄间隙双洞隧道应在开挖后及时进行支护施工,隧道锚在开挖过程中的变形较小,最大变形为1.6mm。施工过程中隧道基本处于受压状态,在洞底位置有小范围应力集中,但集中区域和塑性区域均很小,满足稳定性和安全性的要求。开挖过程中窄间隙隧道锚的应力变化规律可为悬索桥锚固隧道的设计和施工提供参考。

超厚硬岩层地下连续墙旋铣入岩技术研究

以深圳市福田区沙头街道金地工业区城市更新单元一期项目01地块基坑支护与土石方工程项目为研究背景,根据工程实际情况,对地下连续墙超厚硬岩层的入岩施工技术进行了深入研究实践。依靠对现有机械设备的组合使用,通过改进施工工艺,完善施工技术,摸索出一种利用旋挖钻机先行引孔、再用双轮铣槽机铣岩成槽的入岩施工技术,极大保证和提升了地下连续墙施工进度和施工质量,降低了施工成本,为国内同类型的深基坑工程地下连续墙超厚硬岩层的入岩施工技术发展提供相关参考。

硬地层防斜打快底部钻具组合结构优化研究

准噶尔盆地阜康地区深部地层岩石硬度高、地层倾角大,传统的钟摆钻具组合提速工具防斜打快效果差。针对这一问题,在对硬地层中使用扭力冲击器提高机械钻速效果分析基础上,提出了既能充分释放钻压、发挥扭力冲击器提速作用,又能在大倾角地层有效防斜的“扭力冲击器+单弯螺杆”底部钻具组合(Bottom Hole Assembly, BHA)。基于平衡趋势分析研究了BHA结构参数对其防斜能力的影响,确定了关键参数。现场应用表明,新设计的BHA能有效实现硬地层防斜打快目的,为深部硬地层钻井作业提供了一定借鉴。

下穿地下构筑物群桩富水砂层盾构通道MJS预加固施工技术研究及应用

下穿地下构筑物群桩富水砂层盾构通道MJS预加固施工技术包括技术原理、实施思路和具体施工步骤,其由密布群桩富水砂层水平引孔、富水砂层水平引孔砂土流失控制、常规水平MJS注浆加固3个环节组成。技术采用引孔机钻杆+外套管进行水平引孔,实现立柱桩和高强度管桩的穿越,以及富水砂层中的长距离成孔,引孔过程中通过双液注浆对注浆线路进行一次加固,同时利用洞口安装的法兰盘+止回阀来进行砂土流失控制,减少引孔对地下构筑物和周边环境的影响,引孔完成后,进行常规MJS注浆加固,达到预加固目标,并形成具体的下穿地下构筑物群桩富水砂层盾构通道MJS预加固施工步骤指导施工,大幅减少对地下构筑物和周边环境的影响,减少泥浆浪费,提高施工效率,经济社会效益较好,具有较好的推广应用价值。

双层壁涡轮叶片短径扇形气膜孔冷却性能数值研究

针对高冷效双层壁涡轮叶片表面应用短径扇形孔设计准则及强化气膜冷却,机理依旧不明的现状,本文利用流固弱耦合数值模拟技术研究了典型7-7-7和11-11-11扇形气膜孔应用于双层壁涡轮叶片设计的冷却特性。在宽范围吹风比下(0.6~2.4),比较了三种扇形气膜孔布置方案,包含叶片两侧同构布局7-7-7孔(简称SH1布局)和11-11-11孔(简称SH2布局)及新提出的异构布局(简称SH3布局),并以常规圆形孔作为比较依据。通过数值结果对比指出:在双层壁表面应用扇形孔代替圆形孔,最低可提升吸力面综合冷却效率17%,压力面7%。然而,扇形孔也会诱导两侧冷却性能差异扩大的现象。应用两侧孔型异构布局,要求在压力侧布置相较于吸力侧各向扩张角更大的扇形孔,可以有效改善叶片内部的流量配置,从而在提升综合冷却效率的基础上兼顾两侧温差缩小。在高吹风比条件下,上述异构诱发的冷却优势更为显著。但相对吸力侧、压力侧对扇形孔型结构参数的敏感性更大。因此,压力侧的异型孔气膜冷却挑战性更大。

双洞八车道公路隧道机械化施工工法转换技术研究

基于深汕西高速公路改扩建项目城仔山隧道大型机械化施工,分析了机械化双侧壁导坑法与机械化台阶法开挖的施工技术特点与局限性,并提出了双侧壁导坑法转台阶法的转换技术。通过数值模拟沉降及应力分析了转换技术的可行性和安全性,结果表明整个施工转换过程掌子面相对稳定,超前支护及洞身支护的结构合理,无安全隐患,可为现场施工进行一定的指导。

城市复杂环境大跨双连拱隧道三导洞法+主洞洞盖法施工技术分析

文中以厦门第二西通道(海沧隧道)工程下穿城市主干道大跨双连拱隧道为依托,对三导洞法+主洞洞盖法施工技术进行分析,为超浅埋、偏压、软弱围岩、大跨度双连拱隧道施工提供了技术支持;采用三导洞法+主洞洞盖法施工关键技术,确保了正洞开挖期间沉降稳定控制,为隧道安全快速的贯通提供了强有力的技术保障。

基于双层孔结构的850nm超细径保偏光子晶体光纤

光子晶体光纤由高纯度石英玻璃制备而成,具备弯曲损耗小、环境适应性强等优点,尤其适用于恶劣应用环境下的高稳定光纤陀螺。传统光子晶体光纤内部微孔占据了较大的空间,导致光纤直径大,并且主要工作波段为1550nm,无法满足小型化、高精度光纤陀螺需求。提出了双层空气孔结构缩小光纤直径,通过微孔尺寸调节降低光纤损耗,并使光纤限制损耗具有偏振相关性,从而实现超细径保偏光子晶体光纤设计。采用“堆积拉制”法制备了Φ60/100μm光子晶体光纤样品,经截断法测试光纤损耗为6.5dB/km@850nm,偏振串音-15dB@100m。

基于神经网络的双层壁叶片异型孔结构强度设计

随着航空发动机领域的飞速发展,热端涡轮叶片服役环境越发恶劣.为了提高叶片的承温能力,行业内提出了双层壁叶片结构,其原理为“外壁承温,内壁承载”.本文针对双层壁叶片气膜孔结构强度问题,采用参数化建模构建叶型及外壁孔结构,通过仿真分析确定孔型设计参数对圆柱型气膜孔、圆锥型扩张孔和簸箕型扩张孔的孔周结构强度的影响,最后根据参数输入及对应响应构建神经网络模型,通过遗传算法优化径向基函数(Radial Basis Function, RBF)神经网络的权值与阈值来提高代理模型的准确性.寻优获得三种不同结构的气膜孔最优孔型设计方案,相较于圆柱型孔,圆锥型扩张孔孔周应力降低了25.12%,簸箕型扩张孔孔周应力降低了22.54%.

双叉排气膜孔交互作用对气膜冷却效率影响

采用高精度红外热像仪测量了平板气膜冷却效率,比较了双叉排孔和单排孔气膜冷却效率,分析了孔间的相互作用,以及吹风比(M=0.65、1.00、1.50)和密度比(DR=1.0,1.5)对气膜冷却效率的影响;同时还采用数值计算方法比较了气膜冷却下的流场。结果表明:单排气膜孔冷却效率随着吹风比的增加而降低,但是双叉排气膜孔冷却效率大大提高,且随着吹风比的增加而增加,但是在展向气膜覆盖效果变差;增加密度比可以提高气膜冷却效率,但是双叉排孔和吹风比的影响相对密度比更大;双叉排孔相比于单排孔,冷却气流在孔下游形成了反肾形涡,较好抑制了气膜吹离。