Sandwich structures with tapered tubes as core:A quasi-static investigation

In this article,the experimental and finite element analysis is utilized to investigate the quasi-static compression features of sandwich constructions built with tapered tubes.3D printing technology was utilized to create the hollow centers of the tapering tubes,with and without corrugations.The results demonstrate that the energy absorption(EA)and specific energy absorption(SEA)of the single corrugated tapered tube sandwich are 51.6% and 19.8% higher,respectively,than those of the conical tube sandwich.Furthermore,the results demonstrate that energy absorbers can benefit from corrugation in order to increase their efficiency.Additionally,the tapered corrugated tubes'resistance to oblique impacts was studied.Compared to a straight tube,the tapered tube is more resistant to oblique loads and has a lower initial peak crushing force(PCF),according to numerical simulations.After conducting a parametric study,it was discovered that the energy absorption performance of the sandwich construction is significantly affected by the amplitude,number of corrugations,and wall thickness.EA and SEA of DTS with corrugation number of 8 increased by 17.4%and 29.6%,respectively,while PCF decreased by 9.2% compared to DTS with corrugation number of 10.

Longitudinal vibration characteristics of a tapered pipe pile considering the vertical support of surrounding soil and construction disturbance

This research is concentrated on the longitudinal vibration of a tapered pipe pile considering the vertical support of the surrounding soil and construction disturbance.First,the pile-soil system is partitioned into finite segments in the vertical direction and the Voigt model is applied to simulate the vertical support of the surrounding soil acting on the pile segment.The surrounding soil is divided into finite ring-shaped zones in the radial direction to consider the construction disturbance.Then,the shear complex stiffness at the pile-soil interface is derived by solving the dynamic equilibrium equation for the soil from the outermost to innermost zone.The displacement impedance at the top of an arbitrary pile segment is obtained by solving the dynamic equilibrium equation for the pile and is combined with the vertical support of the surrounding soil to derive the displacement impedance at the bottom of the upper adjacent segment.Further,the displacement impedance at the pile head is obtained based on the impedance function transfer technique.Finally,the reliability of the proposed solution is verified,followed by a sensitivity analysis concerning the coupling effect of the pile parameters,construction disturbance and the vertical support of the surrounding soil on the displacement impedance of the pile.

Mechanism of Thermally Radiative Prandtl Nanofluids and Double-Diffusive Convection in Tapered Channel on Peristaltic Flow with Viscous Dissipation and Induced Magnetic Field

The application of mathematical modeling to biological fluids is of utmost importance, as it has diverse applicationsin medicine. The peristaltic mechanism plays a crucial role in understanding numerous biological flows. In thispaper, we present a theoretical investigation of the double diffusion convection in the peristaltic transport of aPrandtl nanofluid through an asymmetric tapered channel under the combined action of thermal radiation andan induced magnetic field. The equations for the current flow scenario are developed, incorporating relevantassumptions, and considering the effect of viscous dissipation. The impact of thermal radiation and doublediffusion on public health is of particular interest. For instance, infrared radiation techniques have been used totreat various skin-related diseases and can also be employed as a measure of thermotherapy for some bones toenhance blood circulation, with radiation increasing blood flow by approximately 80%. To solve the governingequations, we employ a numerical method with the aid of symbolic software such as Mathematica and MATLAB.The velocity, magnetic force function, pressure rise, temperature, solute (species) concentration, and nanoparticlevolume fraction profiles are analytically derived and graphically displayed. The results outcomes are compared withthe findings of limiting situations for verification.

MOTION ANALYSIS OF TAPER MACHINING USING FOUR-AXIS WEDM MACHINE TOOL

The configuration and the reference frame of the four-axis wire-electric discharge machining （WEDM） machine tool are introduced. Based on the motion analysis of the four-axis WEDM machine tool, an algorithm for controlling the four-axis motion is proposed. The algorithm is applicable to both the invariable and variable taper machining. Motion loci of the machining platform and the wire guiding head are deduced by the algorithm according to the bottom surface locus of the workpiece and the taper angle. The algorithm is used in the CNC system of the four-axis WEDM machine tool and confirmed to be effective.

机用ProTaper镍钛器械治疗1208例患牙的临床体会

目的:观察使用机用ProTaper镍钛器械进行根管治疗的疗效。方法:收集作者2007-07～2009-07使用ProTaper镍钛器械做根管治疗的1208例患牙,进行术后X线观察及疗效分析。结果:1 208例患牙中,862例牙髓病变治疗成功率98%,346例根尖周病患者治疗成功率93.3%。结论:机用ProTaper镍钛器械预备根管省时、省力,并能较好的保持根管原有形态,大大减少了根管治疗术后并发症,在根管治疗上有较明显优势。

基于锥形超晶格p-AlInGaN层的AlGaN基深紫外发光二极管性能优化

为了解决AlGaN基深紫外(DUV)发光二极管(LED)中的严重电子溢出和低空穴注入的问题,本文提出了一种新型锥形超晶格p-AlInGaN层,它大幅改善了基于AlGaN的DUV LED的光电特性.与传统结构相比,所提出结构的输出功率提高了337.8%;同时它的内部量子效率(IQE)也高达96%,并且没有效率下降现象.仿真计算结果表明,锥形超晶格p-AlInGaN层的引入明显增加了多量子阱(MQWs)内载流子的浓度并降低了量子阱(QWs)内的电场,导致了更高的辐射复合率,为改善DUV LED的性能提供了一个有吸引力的解决方案.

Design of Tapered Rib Spot-Size Converter with Double-Cladding Structure

A novel structure of spot size converter is designed to allow low loss and large alignment tolerance between single mode rib waveguide devices and fiber arrays theoretically.The spot size converter consists of a tapered rib core region and a double cladding region.Through optimizing parameters,an expanded mode field can be tightly confined in the inner cladding and thus radiation loss be reduced largely at the tapered region.The influence of refractive index and thickness of the inner cladding on coupling loss is analyzed in particular.A novel,easy method of fabricating tapered rib spot size converter based on silicon on insulator material is proposed.

应用ProTaper镍钛系统去除根管内牙胶

目的评价不同方法去除根管内牙胶的效果。方法选取60颗下颌前磨牙,逐步后退法预备根管,AH-plus糊剂加牙胶尖冷侧压充填,保存2周后随机分为3组,每组20颗离体牙。A组使用不锈钢器械联合氯仿治疗,B组使用Pro Taper镍钛系统治疗,C组使用Pro Taper镍钛系统联合显微镜下超声冲洗,分别去除根管内的充填物。记录各组的工作所用时间,并观察3组根管壁的清洁度。结果 C组所用时间和根尖孔碎屑量均明显低于A组和B组,差异具有统计学意义(P<0.05),C组根管壁的清洁度明显优于A组和B组,差异均具有统计学意义(P<0.05)。结论根管再治疗中,配合使用显微超声技术可提高机用镍钛器械工作效率,提高根管壁的清洁度。

High-Power Ridge-Waveguide Tapered Diode Lasers at 980nm

High-power ridge-waveguide tapered InGaAs-AlGaAs lasers emitting at 980nm were fabricated. Lasers with a total length L = 1850μm and different lengths of the ridge waveguide Lrw were processed to study the influence of the straight section on the spatial mode filtering. When Lrw is 450μm, the devices have the optimized maxi- mum output power and beam quality,and the output power P is 4. 28W. The beam propagation ratio M2 is 3. 79 at 1W.

机用Pro Taper、R-Endo根管预备的效果评价

目的评价机用镍钛器械Pro Taper和R-Endo根备系统预备根管的临床效果。方法选择临床上需进行根管治疗的160颗患牙(共512个根管),随机分为实验组(253个根管)和对照组(259个根管),每组各80颗牙。实验组使用机用镍钛器械Pro Taper技术预备根管,对照组使用R-Endo技术预备根管。两组均用冷牙胶侧方加压技术充填根管。记录两组根管预备时间和术后并发症出现情况,根据治疗前、中、后的X线片评价根管预备和充填的效果。结果实验组根管预备时间为15 min,明显少于对照组40 min,根管成形和充填效果两组无差异。结论机用Pro Taper系统应用于根管治疗预备具有良好的成形和充填效果,且根管预备快速、高效;R-Endo系统操作简单,对根尖周组织激惹度较小。

微纳Taper光纤干涉传感器的折射率测量理论研究

利用微纳taper光纤干涉方程和微纳光纤传输模式函数关系,建立了微纳taper光纤干涉波长随环境折射率变化的数学模型,指出微纳taper光纤干涉波长的响应规律由基模高阶模有效折射率差、色散因子和环境折射率3个因素所决定.详细研究了微纳taper光纤传感器的灵敏度变化规律,结果表明,传感器的灵敏度随光纤半径变小而急速增大,并随环境折射率的增大而非线性增加,而且探测波长越长,其灵敏度越大.

Ultra-wideband bilateral tapered slot-line antenna fed by coplanar waveguide

In order to broaden the bandwidth of a tapered slot- line antenna （TSA）, a bilateral tapered slot-line antenna （BTSA） with a new feeding structure of coplanar waveguide （CPW） is developed. Based on the fact that the bandwidth limitation of TSA mainly depends on its feeding structure, an improved CPW-based feed structure etched on the backboard of the BTSA is adopted to perform traveling-wave transition. Both the simulation results and measurement data verify that the proposed feeding structure results in ＂high-pass＂ frequency response for antenna impedance matching. The voltage standing wave ratio （VSWR） is less than 2：1 when the frequency is higher than 3 GHz. The antenna gain exceeds 7 dBi with good radiation patterns when the bandwidth is from 4 to 16 GHz. This ultra wideband （UWB） antenna with a compact size is specially available for the electronic systems of counter-measure and microwave imaging.

Segmented taper equations with crown ratio and stand density for Dahurian Larch (Larix gmelinii) in Northeastern China

Segmented taper equation was selected to model stem profile of Dahurian larch （Larix gmelinii Rupr.）. The data were based on stem analysis of 74 trees from Dailing Forest Bureau in Heilongjiang Province, Northeastern China. Two taper equations with crown ratio and stand basal area were derived from the Max and Burkhart’s （1976） taper equation. Three taper equations were evaluated： （1） the original equation, （2） the original equation with crown ratio, and （3） the original equation with basal area. SAS NLIN and SYSNLIN procedures were used to fit taper equations. Fit statistics and cross-validation were used to evaluate the accuracy and precision of these models. Parameter estimates showed that the original equation with inclusion of crown ratio and basal area variables provided significantly different parameter estimates with lower standard errors. Overall fit statistics indicated that the root mean square error （RMSE） for diameter outside and inside bark decreased respectively by 10% and 7% in the original model with crown ratio and by 12% and 7.2% in the original model with basal area. Cross-validation further confirmed that the original equation with inclusion of crown ratio and basal area variables provided more accurate predictions at the lower section （relative heights, 10%） and upper section （relative heights, 50%） for both outside and inside bark diameters.

The micropolar fluid model for blood flow through a tapered artery with a stenosis

A micropolar model for axisymmetric blood flow through an axially nonsymmetreic but radially symmetric mild stenosis tapered artery is presented. To estimate the effect of the stenosis shape, a suitable geometry has been considered such that the axial shape of the stenosis can be changed easily just by varying a parameter （referred to as the shape parameter）. The model is also used to study the effect of the taper angle Ф. Flow parameters such as the velocity, the resistance to flow （the resistance impedance）, the wall shear stress distribution in the stenotic region and its magnitude at the maximum height of the stenosis （stenosis throat） have been computed for different values of the shape parameter n, the taper angle Ф, the coupling number N and the micropolar parameter m. It is shown that the resistance to flow decreases with increasing the shape parameter n and the micropolar parameter m while it increases with increasing the coupling number N. So, the magnitude of the resistance impedance is higher for a micropolar fluid than that for a Newtonian fluid model. Finally, the velocity profile, the wall shear stress distribution in the stenotic region and its magnitude at the maximum height of the stenosis are discussed for different values of the parameters involved on the problem.

ProTaper专用牙胶与普通大锥度牙胶在根管充填中的临床应用

目的:探讨ProTaper专用牙胶及普通大锥度牙胶在临床中的应用方法及效果。方法:离体单根管恒牙132个,粗、细根管各66个,分别随机分为6组,每组10个,余12个分别作为阳性和阴性对照;比较普通大锥度牙胶尖(Genl-主尖)和ProTaper专用牙胶尖(Pro-主尖)在根管充填效率和封闭性方面的差异;结合染料渗透法和透明标本法,测量根尖微渗漏长度以评价各组根尖封闭能力。结果:细根管Pro-主尖和Genl-主尖在充填时间及根尖封闭性方面无显著差异;粗根管:使用Pro-主尖进行冷侧压充填比使用Genl-主尖更节省充填时间,但两者根尖封闭性方面无显著差别,粗大根管用热牙胶充填法更节省时间;使用Pro-主尖或Genl-主尖进行单尖充填的根尖封闭效果均不佳。结论:ProTaper专用牙胶尖不适合进行单尖充填;对于较粗大根管进行冷侧压充填,使用ProTaper专用牙胶较使用普通锥度牙胶更节省充填时间。

Transverse free vibration analysis of a tapered Timoshenko beam on visco-Pasternak foundations using the interpolating matrix method

The characteristics of transverse free vibration of a tapered Timoshenko beam under an axially conservative compression resting on visco-Pasternak foundations are investigated by the interpolating matrix method. The research is executed in view of a three-parameter foundation which includes the eff ects of the Winkler coeffi cient, Pasternak coeffi cient and damping coeffi cient of the elastic medium. The governing equations of free vibration of a non-prismatic Timoshenko beam under an axially conservative force resting on visco-Pasternak foundations are transformed into ordinary diff erential equations with variable coeffi cients in light of the bending rotation angle and transverse displacement. All the natural frequencies orders together with the corresponding mode shapes of the beam are calculated at the same time, and a good convergence and accuracy of the proposed method is verifi ed through two numerical examples. The infl uences of foundation mechanical characteristics together with rotary inertia and shear deformation on natural frequencies of the beam with diff erent taper ratios are analyzed. A comprehensive parametric numerical study is carried out emphasizing the primary parameters that describe the dynamic property of the beam.

平面波导微型光谱仪系统芯片中Taper耦合结构的研究

设计了一种专用于平面波导微型光谱仪的Taper耦合器。推导了基于三维有限差分光束传播法的标量方程,并利用光束传播法和透明边界条件对耦合器的耦合效率进行了模拟计算和分析。结果表明,Taper耦合器结构稳定,耦合效率高,可满足微型光谱仪的应用要求。

Tapered Suction Caissons:A Numerical Investigation into Their Pull-out Performance

Suction caissons have been widely used as anchors and foundations for floating and fixed offshore platforms. The pull-out performance of conventional suction caissons （with upright walls） has been investigated by a number of researchers. However, no attention has been paid to tapered suction caissons. This paper deals with the performance of tapered suction caissons under vertical pull-out loads. A numerical approach is used for this purpose. The numerical model is first verified against test data available for common upright caissons. The verified model is then used to study the pullout performance of tapered suction caissons. It is noticed that the pull-out capacities exhibited by tapered suction caissons are in general considerably higher than those from their corresponding traditional upright caissons. To obtain an insight into this superior behaviour, effects from certain soil/caisson/drainage parameters on the pull-out capacity of tapered suction caissons are studied. Soil cohesion is noticed to have a linear improving effect on the capacity of both upright and ta- pered suction caissons. The soil internal friction angle is noticed to have an exponential increasing effect on the pull-out capacity. With a constant caisson diameter, an increase in the aspect ratio is seen to particularly influence the pull-out capacity. With a constant caisson length, an increase in the aspect ratio is discovered to result in non-linear decrease in the pull-out capacity. Under undrained conditions, tapered models generally show less sensitivity to above mentioned soil/caisson parameters as compared with those under drained conditions.

Anaerobic tapered fluidized bed reactor for starch wastewater treatment and modeling using multilayer perceptron neural network

treatability of synthetic sago wastewater was investigated in a laboratory anaerobic tapered fluidized bed reactor （ATFBR） with a mesoporous granular activated carbon （GAC） as a support material. The experimental protocol was defined to examine the effect of the maximum organic loading rate （OLR）, hydraulic retention time （HRT）, the efficiency of the reactor and to report on its steady- state performance. The reactor was subjected to a steady-state operation over a range of OLR up to 85.44 kg COD/（m^3·d）. The COD removal efficiency was found to be 92% in the reactor while the biogas produced in the digester reached 25.38 m^3/（m^3·d） of the reactor. With the increase of OLR from 83.7 kg COD/（m^3·d）, the COD removal efficiency decreased. Also an artificial neural network （ANN） model using multilayer perceptron （MLP） has been developed for a system of two input variable and five output dependent variables. For the training of the input-output data, the experimental values obtained have been used. The output parameters predicted have been found to be much closer to the corresponding experimental ones and the model was validated for 30% of the untrained data. The mean square error （MSE） was found to be only 0.0146.

Torsional dynamic response of tapered pile considering compaction effect and stress diffusion effect

Considering both the compaction effect of pile surrounding soil and the stress diffusion effect of pile end soil,this paper theoretically investigates the torsional vibration characteristics of tapered pile.Utilizing the complex stiffness transfer model to simulate compaction effect and tapered fictitious soil pile model to simulate stress diffusion,the analytical solution for the torsional impedance at tapered pile top is obtained by virtue of Laplace transform technique and impedance transfer method.Based on the present solution,a parametric study is conducted to investigate the rationality of the present solution and the influence of soil and pile properties on the torsional vibration characteristics of tapered pile embedded in layered soil.The results show that,both the compaction effect and stress diffusion effect have significant influence on the torsional vibration characteristics of tapered pile,and these two factors should be considered during the dynamic design of pile foundation.