shear

摘要： Ghana is rich in forest resources, of whichTerminalia catappa, a wood species of common occurrence is one. Even though sometimes it is used for decorative purposes, however, it grows in the wild. It grows in almost all the regions of the country and does well in the tropics. The parts of the tree such as the leaves, fruits and seeds have been known to be very useful for medicinal and other uses. Some work on the strength properties of the leaves and other parts has also been done, however, strength properties of the wood are yet to be explored. In this study, its mechanical properties such as bending strength, compression parallel to the grain, and shear parallel to the grain properties were determined. The British (BS 373, 1957) and American Society of Testing Materials’ specifications (ASTM D143, 1983) using testing methods for small, clear specimens of wood were used in determining the properties. The results showed that at 18% moisture content the wood has a density of 520 kg/m3 with a mean modulus of rupture of 86.04 Mpa, compressive strength parallel to the grain of 42.02 Mpa, modulus of elasticity of 10,500 Mpa, and shear strength parallel to the grain of 16.42 N/mm2. These strength properties are comparable to that of Strombosia glaucescens. Therefore, T. catappa can be used in applications where this species is used.

摘要： This study proposes an alternative approach to the investigation of high flow hydrogeological fractures within the basement in the Dabakala region of north-central Côte d’Ivoire. The used approach consists of exploring the subsurface by measuring electrical resistivity contrasts along the main shear direction within crystallophyllian rocks. Electrical resistivity profiling and vertical electrical sounding techniques, coupled with boreholes monitoring, have identified fractured aquifers whose best flow rates are around 96 and 116 m3/h. These aquifers mostly hosted in granodiorite have an average strength of 10 meters and are located at depth of around 100 meters. They are associated with open fractures created by tangential shear stresses that have affected the Dabakala volcano-sedimentary trench formations. The search for fractured aquifers along the main shear direction offers great perspective for obtaining high flow rates.

摘要： Near-inertial motions contribute most of the velocity shear in the upper ocean.In the Bay of Bengal(BoB),the annual-mean energy flux from the wind to near-inertial motions in the mixed layer in 2013 is dominated by tropical cyclone(TC)processes.However,due to the lack of long-term observations of velocity profiles,our knowledge about interior near-inertial waves(NIWs)as well as their shear features is limited.In this study,we quantified the contribution of NIWs to shear by integrating the wavenumber-frequency spectra estimated from velocity profiles in the upper layers(40-440 m)of the southern Bo B from April 2013 to May 2014.It is shown that the annual-mean proportion of near-inertial shear out of the total is approximately 50%,and the high contribution is mainly due to the enhancement of the TC processes during which the near-inertial shear accounts for nearly 80%of the total.In the steady monsoon seasons,the near-inertial shear is dominant to or at least comparable with the subinertial shear.The contribution of NIWs to the total shear is lower during the summer monsoon than during the winter monsoon owing to more active mesoscale eddies and higher subinertial shear during the summer monsoon.The Doppler shifting of the M_(2)internal tide has little effect on the main results since the proportion of shear from the tidal motions is much lower than that from the near-inertial and subinertial motions.

摘要： In this study,the pyramidal lattice stitched foam sandwich composite materials were manufactured by integrating top and bottom panels with pyramidal lattice core to overcome the weak interface between the core and the skins of the sandwich structure.The influence of the reinforcing core rods on the mechanical properties including compressive,shear,and three-point bending performances of the foam sandwich compositematerialswere revealed through theoretical analysis and comparative experiments.The theoretical predictions were consistent with the experimental results.Compressive test,shear test and three-point bending test were performed.The experimental results show that the core rods can significantly improve the compressive performance and energy absorption efficiency of the pyramidal lattice stitched foam sandwich structure.The effect is related to the diameter of the core rod.The core rod with large diameter has better effect.Compared with the foamsandwich structure,the pyramidal lattice reinforcing foam composites have stronger shear and bending resistance.The failure modes and failure mechanisms of the pyramidal lattice stitched foam sandwich structure under the shear load are given.The failure modes and failure mechanisms of the pyramidal lattice stitched foam sandwich structure under the three-point bending load are also given.The study concludes that compared with the foam sandwich structure,the overall mechanical properties of the lattice stitched foam sandwich structure composites are significantly improved.

摘要： Sand Compaction Piles(SCP)commonly known as Sand Columns(SC)now has been vastly used for reinforcing the range of soft soils.The installation of sand columns results in enhancing the ultimate bearing capacity of soft soil,increase the rate of consolidation,prevention of liquefaction in loose sandy soils and provide lateral resistance against the horizontal movement.This research aims at investigating the effects of floating columns in clayey soil with silty deposits by developing small scale laboratory models.The laboratory tests were conducted on a circular column of 37 mm diameter and results of the treated ground are compared to the untreated ground.The effects of sand columns on soils of different shear strengths(low-medium-high),slenderness ratio(L/D)of columns and different loading pattern are investigated.Group effect was also investigated by varying the spacing between the columns.The equivalent entire area of test model was loaded to determine the stiffness of composite ground and axial capacity of sand column was determined by loading the column area alone.Based on current study,it was concluded that sand column can significantly enhance the engineering properties of soft clayey soil.Also,the group effect was studied and it was concluded that by increasing the spacing between the columns,the group efficiency decreases.The axial capacity of sand columns decreases while increasing the spacing between the columns.

摘要： This study utilized cantilever experiments to investigate the vibration properties of multibody molded beetle elytron plates(BEPs),which is a type of biomimetic sandwich plate inspired by beetle elytra;the corresponding shear characteristics were further revealed by a finite element method(FEM). The following results were obtained:(1) Experimental results suggest that the maximum displacement response of the BEPs was about 25% less than that of a honeycomb plate with almost the same first natural frequency,which indicates that a BEP with reasonable structural parameters has the potential to replace a honeycomb plate to achieve better vibration performance;(2) The trabecular structure not only enhanced the shear stiffness of the core layer in column areas but also the skins in the honeycomb wall areas,thus changing the distribution of the shear force in the different components and improving the mechanical performances of the BEP;and(3) Although this enhancement effect from trabeculae was not uniform,the average shear force proportion of the skins(or core structure) in the entire BEP structure was very close to that of the honeycomb plate. Therefore,the shear calculation assumption used for honeycomb plates is still applicable in the BEP.The results provide an experimental basis for the design and application of BEPs and inspiration for the development of related products in vibrational environments.

摘要： Previous quasi-static cyclic tests of shear walls,which routinely used an incremental lateral displacement test protocol with a constant axial load,failed to reflect the character of moment-shear force interaction of prototype buildings.To study the effect of the moment-shear force interaction on the seismic performance of shear walls,three identical 2-story shear wall specimens with different loading patterns were constructed at 1/2 scale,to represent the lower portion of an 11-story high-rise building,and were tested under reversed cyclic loads.The axial force,shear force and bending moment were simultaneously applied to simulate the effects of gravity loads and earthquake excitations on the prototype.The axial force and bending moment delivered from the upper structure were applied to the top of the specimens by two vertical actuators,and the shear force was applied to the specimens by two horizontal actuators.A mixed force-displacement control test program was adopted to ensure that the bending moment and the lateral shear were increased proportionally.The experimental results show that the moment-shear force interaction had a significant effect on the failure pattern,hysteretic characteristics,ductility and energy dissipation of the specimens.It is recommended that moment-shear force interaction should be considered in the loading condition of RC shear wall substructures cyclic tests.

摘要： Focal adhesions are polyproteins linked to extracellular matrix and cytoskeleton,which play an important role in the process of transforming force signals into intracellular chemical signals and subsequently triggering related physiological or pathological reactions.The cytoskeleton is a network of protein fibers in the cytoplasm,which is composed of microfilaments,microtubules,intermediate filaments,and cross-linked proteins.It is a very important structure for cells to maintain their basic morphology.This review summarizes the process of fluid shear stress transduction mediated by focal adhesion and the key role of the cytoskeleton in this process,which focuses on the focal adhesion and cytoskeleton systems.The important proteins involved in signal transduction in focal adhesion are introduced emphatically.The relationship between focal adhesion and mechanical transduction pathways are discussed.In this review,we discuss the relationship between fluid shear stress and associated diseases such as atherosclerosis,as well as its role in clinical research and drug development.

摘要： The radial shear from an elementary theory is proposed to be operating inside a hurricane throughout a major portion of its life cycle: horizontal shear equals the Coriolis parameter. Typical values for the maximum wind speeds at sea level and storm diameters can satisfy this equation, but more detailed observations will be needed in the future for a convincing confirmation.

摘要： 本发明公开了一种基于shear变换和引导滤波器的书法字提取方法，属于图像处理领域。所述发明包括将书法作品进行色彩空间转换并提取第一通道，并且将书法作品的二值化图像作为形质模板，接着分别对第一通道和形质模板进行shear变换得到第一图像集合和第二图像集合，将二者在引导滤波器中进行处理，并对处理结果进行逆shear变换，最终将变换结果进行融合得到融合后图像。本发明通过使用了引导滤波器和shear变换，使得得到的结果带有更多方向上的细节，以便更好地提取书法作品中汉字的形质和神采信息，提高了汉字信息提取的准确性，并结合融合处理将不同方向上提取的书法字的信息进行相互补充，保证了图像中汉字神采信息的完整性，弥补了现有技术中存在缺陷。

摘要： 本发明公开了一种基于shear let域内峰度特性的井中微地震初至波拾取方法，包括步骤1：获取一组二维地震信号，进行离散shear let变换，将所述二维地震信号分解到m个尺度，每个尺度包含n个方向；步骤2：计算相邻高频尺度各个方向的相关能量，每个所述高频尺度内获取n/2个相关能量较高的方向并将其对应的方向系数叠加作为每个高频尺度的对应尺度系数；步骤3：计算每个高频尺度的对应尺度系数的峰度K，求取所述峰度的微分值最大点，位置靠前的点为微地震初至波的初至点；能够根据微地震信号固有的二维时空方向性，对相邻尺度上各方向系数相关能量进行计算，确定有效信号集中的方向，更加准确拾取微地震初至波。

摘要： 本发明公开了一种基于shear变换和引导滤波器的书法字提取方法，属于图像处理领域。所述发明包括将书法作品进行色彩空间转换并提取第一通道，并且将书法作品的二值化图像作为形质模板，接着分别对第一通道和形质模板进行shear变换得到第一图像集合和第二图像集合，将二者在引导滤波器中进行处理，并对处理结果进行逆shear变换，最终将变换结果进行融合得到融合后图像。本发明通过使用了引导滤波器和shear变换，使得得到的结果带有更多方向上的细节，以便更好地提取书法作品中汉字的形质和神采信息，提高了汉字信息提取的准确性，并结合融合处理将不同方向上提取的书法字的信息进行相互补充，保证了图像中汉字神采信息的完整性，弥补了现有技术中存在缺陷。