Dynamic and electrical responses of a curved sandwich beam with glass reinforced laminate layers and a pliable core in the presence of a piezoelectric layer under low-velocity impact

The dynamic responses and generated voltage in a curved sandwich beam with glass reinforced laminate(GRL)layers and a pliable core in the presence of a piezoelectric layer under low-velocity impact(LVI)are investigated.The current study aims to carry out a dynamic analysis on the sandwich beam when the impactor hits the top face sheet with an initial velocity.For the layer analysis,the high-order shear deformation theory(HSDT)and Frostig's second model for the displacement fields of the core layer are used.The classical non-adhesive elastic contact theory and Hunter's principle are used to calculate the dynamic responses in terms of time.In order to validate the analytical method,the outcomes of the current investigation are compared with those gained by the experimental tests carried out by other researchers for a rectangular composite plate subject to the LVI.Finite element(FE)simulations are conducted by means of the ABAQUS software.The effects of the parameters such as foam modulus,layer material,fiber angle,impactor mass,and its velocity on the generated voltage are reviewed.

高承压含水层突水灾害双层孔治理关键技术

针对采煤工作面底板奥灰含水层难以形成高水压堵水塞的技术难题,以古城煤矿3315工作面奥灰突水灾害治理工程为例,提出了地面双层定向水平孔治理方法,利用上层孔对高承压动水进行减速减压,下层孔对动水通道进行快速截流。同时根据工程实践,研究了高承压突水双层治理孔布孔原则、骨料灌注方法、注浆方式和注浆结束标准,形成了双层孔突水灾害治理关键技术。结果表明,双层定向孔对快速探查突水通道、构建堵水塞效果明显,堵水率达100%。

Characteristics of head wave in multi-layered half-space

In this article, we analyze the dynamic characteristics of head wave in multi-layered half-space media models with high-velocity layer or low-velocity layer, and the model with a continuous transition-zone between the crust and the mantle by using synthetic seismogram. It is concluded that the dynamic characteristics of head wave are sensitive to the thickness and velocity of the high-velocity layer. There is obvious diffraction phenomenon of seismic wave if the thickness of high-velocity layer is very small compared with the characteristic wavelength. In this case, the high-velocity layer cannot shield the head wave propagating along the upper interface of the media below it, and the amplitude of this head wave is proportional to the thickness or the velocity of the high-velocity layer. When the thickness of high-velocity layer is nearly identical to the characteristic wavelength of seismic wave, the wave phases reflected from the bottom of the high-velocity layer and the head wave phase may have very close arrival and weaken each other because of destructive interference. As to low-velocity layer, the amplitude of the head wave is weak and decreases with the velocity of this layer. It is also found that if a continuous transition-zone between the crust and the mantle is introduced, we can get a strong apparent head wave phase in synthetic seismogram and the amplitude of this phase increases with the thickness or velocity gradient of the transition-zone.

低降速带资料解释新方法及其可视化研究

在以往的小折射解释中 ,都是假设地表地层水平 ,介质均匀 ,不考虑地层倾斜和倾角 ,计算的层速度存在误差 (倾角较大时误差更大 ) ,也无法预测地层视倾向和视倾角。给出了一种基于均匀介质倾斜界面模型的小折射射线追踪新方法 ,可以计算地层层速度、厚度及地层视倾角 (沿小折射排列方向 ) ;同时 ,针对目前微测井解释普遍采用直线法的情况 ,提出了一种新方法———射线追踪折线法 ,该方法考虑了射线的偏折效应。当井口偏移距较小时 ,直线法和折线法求取的层速度和地层真速度吻合 ;但当偏移距较大时 ,直线法求得的层速度不再适用 ,而折线法求出的层速度仍然比较准确。在这两种新方法的基础上 ,利用可视化技术实现地表属性的三维可视化 。

准噶尔盆地巨厚沙漠区地震勘探关键技术及其应用效果

准噶尔盆地巨厚沙漠区地表沙丘起伏剧烈,低降速带巨厚,对地震波能量吸收衰减严重,地震资料采集激发接收困难,静校正处理问题突出.针对以上难点,开展了基于超深微测井的巨厚沙漠区表层特征调查分析,采用子波和Q值辅助分层方法,对近地表进行了准确分层,获得了准噶尔盆地巨厚沙漠区近地表特征新认识.在此基础上将地震波激发岩性由原来的降速层干沙层改为低速层湿沙层,通过理论和野外试验结合,优选了最佳多浅井组合激发方式及参数;通过检波器埋深试验,确定了20~40cm浅地表潮湿沙层埋置检波器的接收方式;对层析核函数进行剖析,推导出菲涅尔层析敏感核函数,形成了菲涅尔体层析反演高精度静校正技术;采用粘弹波动方程波场延拓近地表吸收衰减补偿技术,消除了巨厚沙漠区近地表吸收衰减的影响.在准噶尔盆地CH1J东、D2J北等多个区块的三维地震勘探中,上述技术的应用提高了地震资料的信噪比,提高了处理剖面的成像精度.

远红外辐射加热对黑木耳的薄层干燥试验

本试验测定了黑木耳的平衡水分，并在给定条件下进行了木耳的薄层干燥试验，发现其干燥过程可分为预热干燥阶段和降速干燥阶段；开始干燥到某一段时间内的湿基水分的变化，可以用２次指数曲线表示；若不控制试料表面温度，进行干燥时试料表面温度与湿基水分呈线性关系。

UG—CAM高速加工工艺探导

选择恰当的CAM软件、生成恰当的适合高速加工的数控加工程序是高速加工的关键。UG-CAM较高计算量的编程速度及防过切自动干涉检查、较好的进给优化处理功能、较丰富的高速加工工艺优化策略及丰富的轨迹规划方法、较好的残余跟踪功能(跟踪指定尺寸刀具以某种路径方式加工不到的剩余部分),超强的待加工轨迹监控功能,较好的拐角及尖角处理工艺,较好的减震功能、强大的插补功能、这些决定了UG-CAM较适合日渐兴起的高速加工工艺。

On the physical model of earthquake precursor fields and the mechanism of precursors＇timespace distribution──origin and evidences of the strong body earthquake──generating model

According to the requirement of the project 'Establishment of the Physical Model of Earthquake PrecursorFields',this paper elucidates the train of thinking for research on the project and some scientific problems whichmust be studied i, the elucidation emphasizes that the core of this project is to study the conditions and processesof the generation of strong earthquakes. The paper first outlines the origin and development of the'strong-bodyearthquake-generating model' proposed by the author in the 1980;and then proves the reasonableness of themodel from three aspects, namely: deep structures, mechanical analysis and rock fracture experiments. Bystudying the tomographic image for the northern part of North China, it can be seen that the sources of strongearthquakes are all distributed in high-velocity bodies,or in the contact zone between high-velocity and lowvelocity bodies but nearer to the high-velocity body. It has been affirmed through studies of the mechanical modelsof hard and soft inclusions that the existence of a hard inclusion is an imPOrtant condition for the high concentration of large amounts of strain energy. A lot of theoretical and experimental studies have been made to investigate the conditions for rock instability; the results have consistently indicated that rock instability,sudden fracture and stress drop would be possible only if the stiffness of the source body is greater than the environmentalstiffness.

Crustal S-wave velocity structure of the Yellowstone region using a seismic ambient noise method

The Yellowstone volcano is one of the largest active volcanoes in the world, and its potential hazards demand detailed seismological and geodetic studies. Previous studies with travel time tomography and receiver functions have revealed a low-velocity layer in the crust beneath the Yellowstone volcano, suggesting the presence of a magma chamber at depth. We use ambient seismic noise from regional seismic stations to retrieve short-period surface waves and then study the shallow shear velocity structure of the Yellowstone region by surface wave dispersion analysis. We first obtained a crustal model of the area outside of the Yellowstone volcano and then constructed an absolute shear wave velocity structure in combination with receiver function results for the crust beneath the Yellowstone volcano. The velocity model shows a low-velocity layer with shear velocity at around 1.3 km/s, suggesting that a large-scale magma chamber exists at shallow levels within the crust of the Yellowstone volcanic region.

The westward drift of the lithosphere:A tidal ratchet?

Is the westerly rotation of the lithosphere an ephemeral accidental recent phenomenon or is it a stable process of Earth's geodynamics? The reason why the tidal drag has been questioned as the mechanism determining the lithospheric shift relative to the underlying mantle is the apparent too high viscosity of the asthenosphere. However, plate boundaries asymmetries are a robust indication of the 'westerly'decoupling of the entire Earth's outer lithospheric shell and new studies support lower viscosities in the low-velocity layer(LVZ) atop the asthenosphere. Since the solid Earth tide oscillation is longer in one side relative to the other due to the contemporaneous Moon's revolution, we demonstrate that a non-linear rheological behavior is expected in the lithosphere mantle interplay. This may provide a sort of ratchet favoring lowering of the LVZ viscosity under shear, allowing decoupling in the LVZ and triggering the westerly motion of the lithosphere relative to the mantle.

Study on the Electrical Conductivity of 0.025 mol NaCl Solution at 0.25-3.75 GPa and 20-370℃

The electrical conductance of 0.025 mol NaCl solution was measured at0.25-3.75 GPa and 20-370℃. As shown by the results, the conductance increases with temper-ature, and there is a liner relation between the reciprocal of temperature and the logarithm ofthe conductance but their slopes are different at different pressures. The relations between theconductance and pressure is rather complex and there are some discontinuities: in the range of2.25-3.75 GPa, the conductance increases with the pressure; in the range of 1.25-2.0 GPa, theconductance is not related to the pressure; and at a pressure of 0.75 GPa, the conductance ishigher than that at the pressures nearby. This reflects that the NaCl solution has rather differentproperties of electronic chemistry at various pressures, and probably is an important cause forthe existence of the layers with high electrical conductance and low velocity in the Earth's crustand mantle.

影响减速伞连接带强度的双因素试验研究

针对某减速伞连接带因多层折叠及局部接触挤压产生应力集中而引起的强度降低问题,采用试验的方法对影响减速伞连接带强度的因素进行了研究。结果表明:连接金属轴直径为32 mm时,2种规格的连接带的破坏位置多出现于缝合部位,当折叠层数为4层时,强度变化系数最大,分别为0.93和0.89,且连接轴直径越小,破坏位置出现在与局部接触部位的几率越大,且强度变化系数最大不超过0.93。试验结果能够有效地指导后续减速伞连接带的设计。

关于聚能声波仪器在气层测井中时差值跳跃的解析

文章根据长期维修聚能声波仪器经验,经过长期跟踪调查,询问野外小队,反映最为常见的是仪器在测井过程中时差跳,无法正常测井。针对这种现象进行分析研究,解析出仪器时差跳得真正原因。

改进k-ω-γ转捩模式对不同雷诺数下HIAD的转捩预测

高超声速充气式柔性减速器(HIAD)在气动力作用下会变形为波纹状,从而促进流动转捩为湍流,准确预测其转捩位置和壁面热流对热防护系统的设计至关重要。拓展了分离诱导转捩预测性能的改进k-ω-γ模式,同时具备对第1模态、第2模态、横流模态以及流动分离失稳的预测能力。本文将其应用于不同雷诺数下壁面波纹变形的HIAD边界层转捩预测,并与原始k-ω-γ模式的预测结果进行了对比,以评估和验证其对复杂转捩现象的预测性能。在此基础上,细致剖析了改进k-ω-γ模式的转捩预测机制。结果表明,改进k-ω-γ转捩模式可准确预测不同来流雷诺数下HIAD的转捩起始位置、转捩阵面形态和壁面热流分布。波纹壁面波峰处的转捩预测主要由构造的分离间歇因子猝发。而在波谷位置,第1模态、横流模态以及流动分离的贡献都很重要。以上研究显示了改进k-ω-γ模式在复杂外形中的应用潜力,可为多重不稳定耦合作用下的转捩预测方法发展提供参考。

Properties of wave velocity for two types of granitoids at high pressure and temperature and their geological meaning

The wave velocity for two types of granitoids was measured using the analytic method of full-wave vibration at high pressure and high temperature. The laws of velocity changes for them differ with the pressure hoost and temperature rise, and the velocity change of S-type is more violent than that of I-type. The 'softening point' of compressional wave velocity ( Vp) is also revealed during the measurement for two types of granitoids imitating the pressure and temperature at a certain depth. But the depth of 'softening', Vp after 'softening' and the percentage of Vp' s drop around the 'softening point' for two types of granitoids are obviously different. The depth of 'softening' is 15 km approximately and Vp after 'softening' is 5. 62 km/s for S-type granitoid. But for I-type granitoid the depth of 'softening' is 26 km approximately and Vp after 'softening' is 6. 08 km/s. Through careful analysis of rock slices after the experiment, it was found that the 'softening' of elastic-wave velocity is caused by the partial melting of granite. Combined with the results of geophysical prospecting, these results suggest that the low-velocity layers developing in the interior of Earth crust are related to the partial melting of different types of granitoids. The formation of the low-velocity layer in the upper-middle Earth crust is closely related to the development of S-type granitoid, but that in the lower Earth crust is closely related to the development of I-type granitoid.

VELOCITY STRUCTURE OF THE CRUST AND UPPER MANTLE IN THE COASTAL REGION OF SOUTH CHINA

Ⅰ. INTRODUCTION The coastal region of South China is located on the southeast tongue of Eurasian plate and borders on the Pacific plate in the east and on the Indian plate in the southwest. Having been driven by three plates, the crust and upper mantle