Reasonable compensation coefficient of maximum gradient in long railway tunnels

This paper deals with the theory and calculation methods for compensation of the gradient in railway tunnels through theoretical analysis, numerical calculation, and statistic regression methods. On the basis of the principle that the resultant force is zero, the formula of the maximum calculated gradient was derived for the freight and passenger line and high-speed passenger special line. The formula of aerodynamic drag in tunnel is provided using the domestic and foreign relevant experimental investigations, and revised with modem train and engineering parameters. A calculation model of aerodynamic drag when the train goes through a single-tracked tunnel was built. Finally, the concept of maximum calculated gradient was adopted to revise the formula for compensation of the gradient in railway tunnels.

Simulation of people's evacuation in tunnel fire

The simulation model Tunev（tunnel evacuation） was developed for people＇s evacuation in tunnel fire. It contains simple database of the people＇s behavioral reaction and structure characteristic parameters of tunnel fireproofing. The model can be used to calculate the total evacuation time in various scenes when fire occurs in the different locations of the tunnel. Combined with fire simulation soft ware CFD- POENICS3.5, Tunev model can be used to calculate the fire danger coming time; by comparing with these two kinds of time, it can be used to assess the safety of the evacuation, and the evacuation process also have a dynamic demo. The simulation results show that the Tunev model can be used to predict the reliability of safe evacuation for people in tunnel fire and provide references for people＇s safe escape scheme. Some relevant concepts of the model were described and an evacuation simulation of a typical tunnel case, i.e. Xuefeng Mountain Tunnel was performed by using this model. And the model＇s validation and actual aoolication were also described.

Characterization of depth-related microbial communities in lake sediment by denaturing gradient gel electrophoresis of amplified 16S rRNA fragments

The characterization of microbial communities of different depth sediment samples was examined by a culture-independent method and compared with physicochemical parameters, those are organic matter （OM）, total nitrogen （TN）, total phosphorus （TP）, pH and redox potential （Eh）. Total genomic DNA was extracted from samples derived from different depths. After they were amplified with the GC-341 f/907r primer sets of partial bacterial 16S rRNA genes, the products were separated by denaturing gradient gel electrophoresis （DGGE）. The profile of DGGE fingerprints of different depth sediment samples revealed that the community structure remained relatively stable along the entire 45 cm sediment core, however, principal-component analysis of DGGE patterns revealed that at greater sediment depths, successional shifts in community structure were evident. The principle coordinates analysis suggested that the bacterial communities along the sediment core could be separated into two groups, which were located 0-20 cm and 21-45 cm, respectively. The sequencing dominant bands demonstrated that the major phylogenetic groups identified by DGGE belonged to Bacillus, Bacterium, Brevibacillus, Exiguobacterium, γ-Proteobacterium, Acinetobacter sp. and some uncultured or unidentified bacteria. The results indicated the existence of highly diverse bacterial community in the lake sediment core.

GRADIENT ESTIMATES FOR SOLUTIONS TO QUASILINEAR ELLIPTIC EQUATIONS WITH CRITICAL SOBOLEV GROWTH AND HARDY POTENTIAL

This note is a continuation of the work[17].We study the following quasilinear elliptic equations- △pu-μ/｜x｜p ｜u｜p-2 u=Q（x）｜u｜Np/N-p -2u,x∈R N,where 1 〈 p 〈 N,0 ≤ μ 〈（（N-p）/p）p and Q ∈ L∞（RN）.Optimal asymptotic estimates on the gradient of solutions are obtained both at the origin and at the infinity.

Characteristics of unsteady flow in porous media while considering threshold pressure gradient with Green＇s function

The flow behavior in porous media with threshold pressure gradient(TPG) is more complex than Darcy flow and the equations of motion, and outer boundary and inner boundary with TPG are also different from Darcy flow for unsteady flow of a producing well in a reservoir. An analytic method to solve this kind of problem is in a need of reestablishment. The classical method of Green's function and Newman product principle in a new way are used to solve the unsteady state flow problems of various shapes of well and reservoir while considering the TPG. Four Green's functions of point, line, band and circle while considering the TPG are achieved. Then, two well models of vertical well and horizontal well are built and simultaneously the function to calculate the moving boundary of each well model is provided. The results show that when considering TPG the pressure field is much different, which has a sudden pressure change, with a moving boundary in it. And the moving boundary of each well model increases with time but slows down rapidly, especially when the TGP is large.

Hamilton-Souplet-Zhang's gradient estimates for two weighted nonlinear parabolic equations

In this paper, we consider gradient estimates for positive solutions to the following weighted nonlinear parabolic equations on a complete smooth metric measure space with only Bakry-Émery Ricci tensor bounded below: One is $${u_t} = {\Delta _f}u + au\log u + bu$$ with a, b two real constants, and another is $${u_t} = {\Delta _f}u + \lambda {u^\alpha }$$ with λ, α two real constants. We obtain local Hamilton-Souplet-Zhang type gradient estimates for the above two nonlinear parabolic equations. In particular, our estimates do not depend on any assumption on f.

Viscoelastic Burger’s model for tunnels supported with tangentially yielding liner

This study proposed an analytical model for the tunnel supported with a tangentially yielding liner in viscoelastic ground.The efficiency of the developed analytical model was verified by comparing the calculated results with associated numerical simulation results.Using the analytical model,a comprehensive parameter sensitivity analysis was performed to examine the effects of the rate of tunnel face advancement,concrete liner thickness,installation time of liner,and strength and thickness of yielding elements on the tunnel responses.The results highlight the significant benefit of the tangentially yielding liner to relieve overstress in the tunnel liner and improve the stability of the tunnel.The yield efficiency of the tangentially yielding liner depends highly on the yielding strength and deformable capacity of the yielding elements and less on the installation time.

Model test of negative Poisson’s ratio cable for supporting super-largespan tunnel using excavation compensation method

In recent years,there is a scenario in urban tunnel constructions to build super-large-span tunnels for traffic diversion and route optimization purposes.However,the increased size makes tunnel support more difficult.Unfortunately,there are few studies on the failure and support mechanism of the surrounding rocks in the excavation of supported tunnel,while most model tests of super-large-span tunnels focus on the failure characteristics of surrounding rocks in tunnel excavation without supports.Based on excavation compensation method(ECM),model tests of a super-large-span tunnel excavation by different anchor cable support methods in the initial support stage were carried out.The results indicate that during excavation of super-large-span tunnel,the stress and displacement of the shallow surrounding rocks decrease,following a step-shape pattern,and the tunnel failure is mainly concentrated on the vault and spandrel areas.Compared with conventional anchor cable supports,the NPR(negative Poisson’s ratio)anchor cable support is more suitable for the initial support stage of the super-large-span tunnels.The tunnel support theory,model test materials,methods,and the results obtained in this study could provide references for study of similar super-large-span tunnels。

Estimation of convergence of a high-speed railway tunnel in weak rocks using an adaptive neuro-fuzzy inference system(ANFIS) approach

Estimation of tunnel diameter convergence is a very important issue for tunneling construction,especially when the new Austrian tunneling method（NATM） is adopted.For this purpose,a systematic convergence measurement is usually implemented to adjust the design during the whole construction,and consequently deadly hazards can be prevented.In this study,a new fuzzy model capable of predicting the diameter convergences of a high-speed railway tunnel was developed on the basis of adaptive neuro-fuzzy inference system（ANFIS） approach.The proposed model used more than 1 000 datasets collected from two different tunnels,i.e.Daguan tunnel No.2 and Yaojia tunnel No.1,which are part of a tunnel located in Hunan Province,China.Six Takagi-Sugeno fuzzy inference systems were constructed by using subtractive clustering method.The data obtained from Daguan tunnel No.2 were used for model training,while the data from Yaojia tunnel No.1 were employed to evaluate the performance of the model.The input parameters include surrounding rock masses（SRM） rating index,ground engineering conditions（GEC） rating index,tunnel overburden（H）,rock density（？）,distance between monitoring station and working face（D）,and elapsed time（T）.The model’s performance was assessed by the variance account for（VAF）,root mean square error（RMSE）,mean absolute percentage error（MAPE） as well as the coefficient of determination（R2） between measured and predicted data as recommended by many researchers.The results showed excellent prediction accuracy and it was suggested that the proposed model can be used to estimate the tunnel convergence and convergence velocity.

GRADIENT TYPE OF GREEN'S FUNCTION FOR PARABOLIC PROBLEM

Consider the piecewise linear finite element subspace S and parabolic semi discrete Green’s function of gradient type G h(t)∈Sk.The asymptotic optimal estimatedxdt【C|Inh| and two applications are discussed.

SWITCHING CHARACTERISTICS AND ANALYSIS OF RESONANT TUNNELING DIODES

Resonant tunneling diode （RTD） of AlAs/InGaAs/AlAs double barrier-single well structure was designed and fabricated. The devices showed current-voltage characteristics with peak-valley current ratio of 4 ： 1 at room temperature. The scattering parameter of RTD was measured by using an HP8510（C） network analyzer. Equivalent circuit parameters were obtained by curve fitting and optimized. The RTD switching time was estimated using the measured capacitance and average negative differential resistance. The minimum rise time of the sample was estimated to be 21 ps.

Variation and Sexual Dimorphism of Body Size in the Plateau Brown Frog along an Altitudinal Gradient

Variation in body size and sexual size dimorphism（SSD） can have important consequences for animal ecology, behavior, population dynamics and the evolution of life-history traits. Organisms are expected to be larger in colder climate（i.e., Bergmann＇s rule） and SSD varies with body size（i.e., Rensch＇s rule）. However, the underlying mechanisms are still elusive. The plateau brown frog（Rana kukunoris）, a medium-sized anuran species with femalebiased SSD, is endemic to the Qinghai-Tibetan Plateau（QTP）. From 1797 m（Maoxiang＇ping） to 3453 m（Heihe＇qiao） in the eastern margin of the QTP, we surveyed 10 populations of R. kukunoris and collected phalanges and snout vent length（SVL） data for 258 adult individuals（199 males versus 59 females）. Based on these data, we explored how body size and SSD varying along the altitudinal gradient and examined the corresponding effects of temperature. We found body size to be larger at higher altitude for males but not for females, with likely effects from the temperature on the variation in male body size. Sex differences in growth rates may be the main cause of the variation in SSD. Our results suggested that only males follow the Bergmann＇s rule and variation in SSD of R. kukunoris do not support the Rensch＇s rule and its inverse. Therefore, the variations of body size can be different between sexes and the applicability of both Bergmann＇s rule and Rensch＇s rule should depend on species and environment where they live.

Total removal of a large esophageal schwannoma by submucosal tunneling endoscopic resection:A case report and review of literature

BACKGROUND Primary schwannoma is a rare submucosal tumor of the esophagus,which is most often benign,and surgery is the only effective treatment.So far,only a few cases have been reported.Herein,we reported a single case diagnosed with primary esophageal schwannoma that was totally removed by submucosal tunneling endoscopic resection(STER).CASE SUMMARY A 62-year-old man presented to the hospital with a history of resection of a malignant gastric tumor and mild dysphagia.Endoscopic examination revealed a large submucosal elevated lesion in the esophagus 25-30 cm from the incisors.Endoscopic ultrasonography detected a 45 mm×35 mm×31 mm hypoechoic lesion;chest computed tomography showed a mass of approximately 55 mm×35 mm×29 mm.A preliminary examination showed features suggestive of a stromal tumor.Pathological findings indicated esophageal schwannoma.Next,STER alone was performed to completely resect the mass,and the patient recovered well post-surgery.Afterward,the patient was discharged and showed no tumor recurrence at 33 mo of follow-up.CONCLUSION Endoscopic resection is still an effective treatment for large esophageal schwannomas(>30 mm)under meticulous morphological evaluation.

Wavelet multiresolution interpolation Galerkin method for nonlinear boundary value problems with localized steep gradients

The wavelet multiresolution interpolation for continuous functions defined on a finite interval is developed in this study by using a simple alternative of transformation matrix.The wavelet multiresolution interpolation Galerkin method that applies this interpolation to represent the unknown function and nonlinear terms independently is proposed to solve the boundary value problems with the mixed Dirichlet-Robin boundary conditions and various nonlinearities,including transcendental ones,in which the discretization process is as simple as that in solving linear problems,and only common two-term connection coefficients are needed.All matrices are independent of unknown node values and lead to high efficiency in the calculation of the residual and Jacobian matrices needed in Newton’s method,which does not require numerical integration in the resulting nonlinear discrete system.The validity of the proposed method is examined through several nonlinear problems with interior or boundary layers.The results demonstrate that the proposed wavelet method shows excellent accuracy and stability against nonuniform grids,and high resolution of localized steep gradients can be achieved by using local refined multiresolution grids.In addition,Newton’s method converges rapidly in solving the nonlinear discrete system created by the proposed wavelet method,including the initial guess far from real solutions.

From Gradient Elasticity to Gradient Interatomic Potentials: The Case-Study of Gradient London Potential

Motivated by the special theory of gradient elasticity (GradEla), a proposal is advanced for extending it to construct gradient models for interatomic potentials, commonly used in atomistic simulations. Our focus is on London’s quantum mechanical potential which is an analytical expression valid until a certain characteristic distance where “attractive” molecular interactions change character and become “repulsive” and cannot be described by the classical form of London’s potential. It turns out that the suggested internal length gradient (ILG) generalization of London’s potential generates both an “attractive” and a “repulsive” branch, and by adjusting the corresponding gradient parameters, the behavior of the empirical Lennard-Jones potentials is theoretically captured.

Anomalous muscles in carpal tunnel associated with neurovascular variations: Case report and brief review

Anomalous muscles in carpal tunnel (CT) may cause carpal tunnel syndrome (CTS), and may be also associated with neurovascular abnormalities, altering the diagnosis and surgical interventions for CTS. The authors report a case of bilateral Gantzer’s muscles (GMs) inserted into the tendons of flexor digitorum profundus within the CTs in an old male cadaver. The left GM was associated with enlarged lumbrical muscles in the CT and bifid median nerve (MN) communicating with ulnar nerve in the hand. The right GM was associated with perforation of MN branches in the hand by superficial palmar arch. This unreported coexistence of anomalous GMs and the associated neurovascular variations may have clinical relevance to etiology, diagnosis and treatment of CTS.

Automated measurement of three-dimensional cerebral cortical thickness in Alzheimer’s patients using localized gradient vector trajectory in fuzzy membership maps

Our purpose in this study was to develop an automated method for measuring three-dimensional (3D) cerebral cortical thicknesses in patients with Alzheimer’s disease (AD) using magnetic resonance (MR) images. Our proposed method consists of mainly three steps. First, a brain parenchymal region was segmented based on brain model matching. Second, a 3D fuzzy membership map for a cerebral cortical region was created by applying a fuzzy c-means (FCM) clustering algorithm to T1-weighted MR images. Third, cerebral cortical thickness was three- dimensionally measured on each cortical surface voxel by using a localized gradient vector trajectory in a fuzzy membership map. Spherical models with 3 mm artificial cortical regions, which were produced using three noise levels of 2%, 5%, and 10%, were employed to evaluate the proposed method. We also applied the proposed method to T1-weighted images obtained from 20 cases, i.e., 10 clinically diagnosed AD cases and 10 clinically normal (CN) subjects. The thicknesses of the 3 mm artificial cortical regions for spherical models with noise levels of 2%, 5%, and 10% were measured by the proposed method as 2.953 ± 0.342, 2.953 ± 0.342 and 2.952 ± 0.343 mm, respectively. Thus the mean thicknesses for the entire cerebral lobar region were 3.1 ± 0.4 mm for AD patients and 3.3 ± 0.4 mm for CN subjects, respectively (p < 0.05). The proposed method could be feasible for measuring the 3D cerebral cortical thickness on individual cortical surface voxels as an atrophy feature in AD.

Tunneling of Relativistic Bosons Induced by Magnetic Fields in the Magnetar’s Crust

The present work is devoted to the study of bosons evolving in the frozen magnetar＇s crust endowed with an ultra-strong magnetic field orthogonal to an electric field, both described by periodic functions. We discuss the quantum tunneling process through the one-dimensional potential barrier along Oz. The solutions to the Klein- Gordon equation are expressed in terms of Mathieu＇s functions which, for computable particle＇s energy range, are turning from oscillatory to exponentially growing modes along Oz. Within the Jeffreys Wentzel Kramers- Brillouin framework, the transmission coefficient is computed for the particle momentum in the middle of the instability range.

Microscopic growth mechanism and edge states of monolayer 1T'-MoTe_(2)

Transition metal ditellurides(TMTDs)have versatile physical properties,including non-trivial topology,Weyl semimetal states and unique spin texture.Controlled growth of high-quality and large-scale monolayer TMTDs with preferred crystal phases is crucial for their applications.Here,we demonstrate the epitaxial growth of 1T'-MoTe_(2) on Au(111)and graphitized silicon carbide(Gr/SiC)by molecular beam epitaxy(MBE).We investigate the morphology of the grown1T'-MoTe_(2) at the atomic level by scanning tunnelling microscopy(STM)and reveal the corresponding microscopic growth mechanism.It is found that the unique ordered Te structures preferentially deposited on Au(111)regulate the growth of monolayer single crystal 1T'-MoTe_(2),while the Mo clusters were preferentially deposited on the Gr/SiC substrate,which impedes the ordered growth of monolayer MoTe_(2).We confirm that the size of single crystal 1T'-MoTe_(2) grown on Au(111)is nearly two orders of magnitude larger than that on Gr/SiC.By scanning tunnelling spectroscopy(STS),we observe that the STS spectrum of the monolayer 1T'-MoTe_(2) nano-island at the edge is different from that at the interior,which exhibits enhanced conductivity.

基于S型映射的自适应粒子群优化算法

针对粒子群算法搜索精度不高,易陷入局部最优解的不足,提出了一种基于S型映射的自适应粒子群优化算法.首先,通过群体适应度方差策略,设定种群收敛阈值;然后,根据阈值采用S型映射自适应变异搜索策略,以提高全局探索能力;最后,根据适应值排序,采用S型映射自适应步长梯度搜索策略,以提高局部搜索能力.通过四个测试函数实验表明,该算法在收敛速度、收敛精度方面均有较大提升.