支架现浇刚性系杆拱桥的吊杆施工张拉力确定方法

针对支架现浇刚性系杆拱桥在吊杆张拉施工过程的吊杆索力计算和调整难题,以采用满堂支架现浇施工的刚性系杆拱桥为研究对象,提出一种新的吊杆施工张拉力确定方法。在该方法中,首先提出了脱架系数的概念,并结合有支架计算模型和无支架计算模型的索力影响矩阵,近似计算得到主梁脱离支架过程中的索力影响矩阵,而后利用该索力影响矩阵进行正装迭代运算,以确定吊杆施工张拉力。为验证该方法的可行性与适用性,将该法应用于江西省吉水县恩江二桥主桥(跨度65m+65m)的吊杆张拉施工中,利用该法计算得到了该桥吊杆2次张拉的施工张拉力,并对吊杆张拉施工结束后的索力进行了测量。结果表明:该方法能较准确地计算主梁支架拆除前的吊杆施工张拉力,收敛速度较快,且收敛效果好;各吊杆的实测索力与目标索力间的误差基本控制在规范允许范围之内,利用该法确定的吊杆施工张拉力来进行吊杆张拉施工,张拉效果良好。

PREPATATION OF SPODUMENE-DERIVED LOW EXPANSION COEFFICIENT GLASS CERAMIC IN THE SYSTEM Li_2O-Al_2O_3-SiO_2

In this paper ,spodumene mineral was used as raw material for fabricating glass ceramic with the addition of MgO,ZnO and TiO2,ZrO2. The expansion coefficient of the materials is 5. 5×107/℃ . Also the effects of the heat treatment on the crystallzing behaviour has been discussed by XRD and DTA.

Self-excited vibration of driveline for vehicle launch

The launch shudder phenomenon induced by self-excited vibration of driveline was stud- ied with a compact car equipped with AMT as research object. The research showed that self-excited vibration was closely related with damping of driveline, the variation of friction coefficient, equiva- lent radius of friction plate and applied force of pressure plate. Six DOFs torsional vibration model of vehicle driveline was established according to the parameters of the certain compact car. The simula- tion was carried out and the result was compared with test data. It was found that the negative slope of friction coefficient with relative slip speed does not necessarily lead to self-excited vibration and the frequency of self-excited vibration on 1st gear is near to the 1st order of torsional natural frequen- cy. The influence of each viscous damping in driveline on self-excited vibration was analyzed by sim- ulation and the results showed that increasing the torsional dampings of half-axles and tires properly was effective to improve launch shudder phenomenon.

Experimental research on thermal transport properties of crystallized palladium-based alloys

Palladium-based alloy is a kind of material with a high glass forming ability and can be easily formed into an amorphous state. After an annealing process, it can also be maintained at a crystallized state. To study the thermal and electrical transport properties of crystallized palladium-based alloys, the steady-state T-type method, standard four-probe method, and AC heating-DC detecting T-type method were used to measure the thermal conductivity, electrical conductivity, and Seebeck coeffi- cient of crystallized Pd4oNiloCu3oP2o and Pd43Nilo- Cu27P2o alloys respectively. The results show that compared to amorphous samples, the thermal conductivity and electrical conductivity of crystallized palladium-based alloys are significantly higher, while the Seebeck coeffi- cient is lower. The ratio of crystallized and amorphous thermal conductivity is higher for Pd43Ni10Cu27P2o alloy fiber which has a higher glass forming ability, while the ratio of electronic thermal conductivity almost remains constant for both alloy fibers. The results also show that the slope of electrical resistivity to temperature is a function of elemental composition for crystallized quaternary palla- dium-based alloy fibers. The sensitivity of thermal conductivity and electrical conductivity to the composition is high, while the correlation between Seebeck coefficient and composition is relatively weak.

Electrical properties and thermal sensitivity of Ti/Y modified CuO-based ceramic thermistors

The Ti/Y modified CuO-based negative temperature coefficient （NTC） thermistors, Cu0.988-2yY0.008TiyO （TYCO; y-- 0.01, 0.015, 0.03, 0.05 and 0.07）, were synthesized through a wet-chemical method followed by a traditional ceramic sintering technology. The related phase component and electrical properties were investigated. XRD results show that the TYCO ceramics have a monoclinic structure as that of CuO crystal. The TYCO ceramics can be obtained at the sintering temperature 970℃-990℃, and display the typical NTC characteristic. The NTC thermal-sensitive constants of TYCO thermistors can be adjusted from 1112 to 3700 K by changing the amount of Ti in the TYCO ceramics. The analysis of complex impedance spectra revealed that both the bulk effect and grain boundary effect contribute to the electrical behavior and the NTC effect. Both the band conduction and electron-hopping models are proposed for the conduction mechanisms in the TYCO thermistors.

An improved cooperative spectrum detection algorithm for cognitive radio

The ability to detect the primary user＇s signal is one of the main performances for cognitive radio networks. Based on the multi-different-cyclic-frequency character- istics of the cyclostationary primary user＇s signal and the cooperation detection advantage of the multi-secondary-user, the paper presents the weighted cooperative spectrum detection algorithm based on cyclostationarity in detail. The core of the algorithm is to detect the primary user＇s signal by the secondary users＇ cooperation detection to the multi-different-cyclic-frequency, and to make a final decision according to the fusion data of the independent secondary users＇ detection results. Meanwhile, in order to improve the detection performance, the paper proposes a method to optimize the weight on basis of the deflection coefficient criterion. The result of simulation shows that the proposed algorithm has better performance even in low signal-to-noise ratio （SNR）.

A microextraction approach for rapid extraction and separation of Mn(Ⅱ) and Co(Ⅱ) using saponified D2EHPA system

In this paper,we proposed a microextraction approach for the extraction and separation of Mn(Ⅱ)and Co(Ⅱ)from sulfate solution simulating leachate of spent lithium-ion battery cathode materials using saponified di-(2-ethylhexyl)phosphoric acid system.The effects of the following operational variables were investigated:equilibrium pH,tri-«-butyl phosphate concentration,saponification rate,two-phase ratio and residence time.The results showcased that the microextractor can reach the extraction equilibrium within 20 s,thereby greatly reducing necessary extraction time comparing to that of conventional processes.The volumetric mass transfer coefficient showed 8-21 times larger than that of batch device.With the help of microextractor,95%of Mn(Ⅱ)was extracted with a single theoretical stage at a chosen two-phase ratio of 3:1,and the separation factor β_(Mn/Co) was as large as 65.5.In the subsequent stripping step,more than 99%of manganese from loaded phase was easily stripped under optimal conditions.The microextraction approach greatly enhances the mass transfer while enabling a continuous and controllable extraction process within a simple structure design.When extracting spent electrode material with microextractors,the comprehensive recovery of mangenese can reach 96%.The microextraction approach has a good applicability in the spent lithium-ion battery cathode materials recycling at both bench and industrial scales.

A Bilinear Immersed Finite Volume Element Method for the Diffusion Equation with Discontinuous Coefficient

This paper is to present a finite volume element(FVE)method based on the bilinear immersed finite element(IFE)for solving the boundary value problems of the diffusion equation with a discontinuous coefficient(interface problem).This method possesses the usual FVE method’s local conservation property and can use a structured mesh or even the Cartesian mesh to solve a boundary value problem whose coefficient has discontinuity along piecewise smooth nontrivial curves.Numerical examples are provided to demonstrate features of this method.In particular,this method can produce a numerical solution to an interface problem with the usual O(h2)(in L2 norm)and O(h)(in H1 norm)convergence rates.