连续多段弧形曲面波纹铝板幕墙安装施工技术

以珠海横琴新区子期幼儿园铝板幕墙为背景,针对结构异形弧形组合不规律、固定幕墙所需的钢结构测量定位难度大、单块幕墙面积过大、项目工期紧张等问题,采用一种法向轴网的方法,保证钢结构预埋件可以准确定位,且可以直接根据深化图进行加工以及幕墙的分段分块安装。经实施,方案很好地保证了幕墙的整体效果,施工效率高。

Forward modeling and inversion of tensor CSAMT in 3D anisotropic media

Tensor controlled-source audio-frequency magnetotellurics （CSAMT） can yield information about electric and magnetic fields owing to its multi-transmitter configuration compared with the common scalar CSAMT. The most current theories, numerical simulations, and inversion of tensor CSAMT are based on far-field measurements and the assumption that underground media have isotropic resistivity. We adopt a three-dimensional （3D） staggered-grid finite difference numerical simulation method to analyze the resistivity in axial anisotropic and isotropic media. We further adopt the limited-memory Broyden- Fletcher-Goldfarb-Shanno （LBFGS） method to perform 3D tensor CSAMT axial anisotropic inversion. The inversion results suggest that when the underground structure is anisotropic, the isotropic inversion will introduce errors to the interpretation.

Comprehensive modeling approach of axial ultrasonic vibration grinding force

The theoretical model of axial ultrasonic vibration grinding force is built on the basis of a mathematical model of cutting deforming force deduced from the assumptions of thickness of the undeformed debris under Rayleigh distribution and a mathematical model of friction based on the theoretical analysis of relative sliding velocity of abrasive and workpiece. Then, the coefficients of the ultrasonic vibration grinding force model are calculated through analysis of nonlinear regression of the theoretical model by using MATLAB, and the law of influence of grinding depth, workpiece speed, frequency and amplitude of the mill on the grinding force is summarized after applying the model to analyze the ultrasonic grinding force. The result of the above-mentioned law shows that the grinding force decreases as frequency and amplitude increase, while increases as grinding depth and workpiece speed increase; the maximum relative error of prediction and experimental values of the normal grinding force is 11.47% and its average relative error is 5.41%; the maximum relative error of the tangential grinding force is 10.14% and its average relative error is 4.29%. The result of employing regression equation to predict ultrasonic grinding force approximates to the experimental data, therefore the accuracy and reliability of the model is verified.

Forced Axial and Torsional Vibrations of a Shaft Line Using the Transfer Matrix Method Related to Solution Coefficients

This present paper deals with a mathematical description of linear axial and torsional vibrations. The normal and tangential stress tensor components produced by axial-torsional deformations and vibrations in the propeller and intermediate shafts, under the influence of propeller-induced static and variable hydrodynamic excitations are also studied. The transfer matrix method related to the constant coefficients of differential equation solutions is used. The advantage of the latter as compared with a well-known method of transfer matrix associated with state vector is the possibility of reducing the number of multiplied matrices when adjacent shaft segments have the same material properties and diameters. The results show that there is no risk of buckling and confirm that the strength of the shaft line depends on the value of the static tangential stresses which is the most important component of the stress tensor.

Combined therapeutic approach:Inflammatory bowel diseases and peripheral or axial arthritis

Inflammatory bowel diseases(IBDs), particularly Crohn's disease(CD) and ulcerative colitis(UC), are associated with a variety of extra-intestinal manifestations(EIMs).About 36% of IBD patients have at least one EIM, which most frequently affect the joints, skin, eyes and the biliary tract.The EIMs associated with IBD have a negative impact on patients with UC and CD, and the resolution of most of them parallels that of the active IBD in terms of timing and required therapy;however, the clinical course of EIMs such as axial arthritis, pyoderma gangrenosum, uveitis, and primary sclerosing cholangitis is independent of IBD activity.The peripheral and axial arthritis associated with IBD have traditionally been treated with simple analgesics, non-steroidal anti-inflammatory drugs, steroids, sulfasalazine, methotrexate, local steroid injections and physiotherapy, but the introduction of biological response modifi ers such as tumor necrosis factor-α blockers, has led to further improvements.

Study of large medical equipment allocation in Xuzhou

Objective: To investigate the allocation and management of large medical equipment (LME) in Xuzhou, Jiangsu Province, China, in order to make the best use of LME to meet the medical needs of local people. Methods: The research collected data from all hospitals that have LME in Xuzhou using questionnaire; 38 (97.4%) hospitals returned the questionnaire. Results: In Xuzhou, there are a total of 71 pieces of LME, each serving 126 600 people in an area of 163 km2. Sixty-two percent of them are allocated in urban areas, with Gini coefficient at 0.52, indicating imbalance and biased allocation of LME. Conclusion: The al- location of LME in Xuzhou is out of control and unfairly allocated.

Particles segregation in rotating drum based on discrete element method

In order to study particle segregation in the rotating drum,the movement of particles is studied by theoretical deduction and numerical simulation.According to the theoretical deduction,particles near the end wall are lifted higher by the friction of the end wall,which leads to small particles gathering in the middle of the drum.The model of particle motion is established based on the discrete element method.It can be shown from the simulation results that the particles accumulated highernear the end w al,which is consistent with the theoretical deduction.In addition,the effects from the aspects of te relative friction between particles,the friction between the end wall a d particle,the drum aspect ratio and the rotation speed were explored by thesimulation.From the simulation results,it can be pointed out that the friction of the eed w a i has a decisive influence on the axial segregation of theparticles,and the other factors merely affect the accumulate forms of particles.

A Roller Bearing Fault Diagnosis Method Based on Improved LMD and SVM

Aiming at the non-stationary feattwes of the roller bearing fault vibration signal, a roller bearing fault diagnosis methtxt based on improved Local Mean Decomposition （LMD） and Support Vector Machine （SVM） is proposed. In this paper, firstly, the wavelet analysis is introduced to the signal decomposition and reconstruction; secondly, the LMD method is used to decompose the recomtnion signal obtained by the wavelet analysis into a ntmaber of Product Ftmctions （PFs） that include main fault characteristics, thus, the initial feattwe vector matrixes could be formed automatically; Thirdly, by applying the Singular Valueition （SVD） techniques to the initial feature vector matrixes, the singular values of the matrixes can be obtained, which can be used as the fault feature vectors of the roller bearing and serve as the input vectors of the SVM classifier; Finally, the recognition results can be obtained from the SVM output. The results of analysis show that the propsed method can be applied to roller beating fault diagnosis effectively.

Finite element formulation of axisymmetric heat transfer problem for orthotropic materials

By using Galerkin’s method, the finite element formulation is made for axisymmtric heat transfer problems for anisotropic materials from the heat transfer differential equations expressed in terms of heat fluid density. Results of an example show that the heat transfer anisotropy has an important effect on temperature field.

论简化Navier-Stokes方程组(SNSE)

本文论述简化 Navier-Stokes 方程组(SNSE),利用十种 SNSE分析Jeffery-Hamel流动并简要分析已知完全 Navier-Stokes 方程组(CNSE)精确解的八类流动。表明:不同SNSE结果之间的实际差异能够大大超出O(Re^(-1/2))量级的理论误差范围,甚至给出不同的流动图案。因此,SNSE 的粘性项如何取舍值得重视。内外层匹配SNSE和薄层二阶SNSE的解在八类流动情况下均与CNSE的精确解完全一致;而所有其它SNSE 的解则与CNSE的精确解不完全一致,它们的解在不少情况下实际就是经典边界层理论的解。内外层匹配SNSE包含了法向轴相对流向轴剪切的剪应力项和法向轴伸缩的法应力项以及与该法应力项同量级的粘性项,且对惯性项和粘性-惯性项相互关系的处理较合理,故在力学上和数学上都比较可取。

Clinical efficacy of electroacupuncture in controlling myopia in children and its influence on retinal blood flow

Objective:To observe the clinical efficacy of electroacupuncture(EA)in controlling myopia in children and its effect on retinal blood flow.Methods:Sixty-eight myopic children were randomly divided into an observation group and a control group,with 34 cases in each group.The control group was given auricular acupressure treatment alone,and the observation group was treated with EA once a week in addition to the treatment used in the control group.The spherical equivalent refraction(SER)and axial length(AL)were measured at baseline,and after 3 months and 6 months of treatment.Optical coherence tomography angiography was used to measure the vessel density(VD)and perfusion density(PD)in the surface layer of the retina.Results:After 3 months and 6 months of treatment,the changes in SER between the two groups were not statistically significant(P>0.05).After 3 months of treatment,the changes in AL between the two groups were not statistically significant(P>0.05);after 6 months of treatment,the change amount of AL in the observation group was smaller than that in the control group(P<0.05);after 3 months and 6 months of treatment,the changes in VD and PD in the surface layer of the retina in the observation group were significantly greater than those in the control group(P<0.01).Conclusion:EA treatment once a week for 6 months can delay the increase of AL and improve the retinal surface blood flow in myopic children.

A CONTROL ALGORITHM FOR RAPID MOVEMENTS NEAR THE RADIUS COMPENSATION SINGULARITY IN FIVE-AXIS END MILLING

When the five-axis CNC system executes the 3D cutter radius compensation function,the angle between two adjacent radius compensation vectors might become very large and the linear axes would move too fast if the tool orientation vector is close to the surface normal.The reason that results in this phenomenon is analyzed based on building the transmission relationship between the cutter contact point and the cutter location point.By taking the square-end tool as an example,an optimization algorithm to control the undesired movements is advanced.For the singular area where sudden change exists,the number of interpolation cycles is determined by the cutter feedrate,the limit speeds of machine axes and the maximum allowable angle between radius compensation vectors of adjacent NC blocks.The radius compensation vector of each interpolation cycle is obtained by a kind of vector rotation method.By maintaining the perpendicularity between the radius compensation vector and the tool orientation vector,the rapid movements of the linear axes are eliminated.A trial-cut experiment is performed to verify the correctness and the effectiveness of the proposed algorithm.

Mathematical modeling of micropolar fluid flow through an overlapping arterial stenosis

In this study a mathematical model for two-dimensional pulsatile blood flow through overlapping constricted tapered vessels is presented. In order to establish resemblance to the in vivo conditions, an improved shape of the time-variant overlapping stenosis in the elastic tapered artery subject to pulsatile pressure gradient is considered. Because it contains a suspension of all erythrocytes, the flowing blood is represented by micropolar fluid. By applying a suitable coordinate transformation, tapered cosine-shaped artery turned into non-tapered rectangular and a rigid artery. The governing nonlinear partial differential equations under the imposed realistic boundary conditions are solved using the finite difference method. The effects of vessel tapering on flow characteristics consid- ering their dependencies with time are investigated. The results show that by increasing the taper angle the axial velocity and volumetric flow rate increase and the microrota- tional velocity and resistive impedance reduce. It has been shown that the results are in agreement with similar data from the literature.