Thermoelastic waves in helical strands with Maxwell–Cattaneo heat conduction

Harmonic thermoelastic waves in helical strands with Maxwell–Cattaneo heat conduction areinvestigated analytically and numerically. The corresponding dispersion relation is a sixth-orderalgebraic equation, governed by six non-dimensional parameters: two thermoelastic couplingconstants, one chirality parameter, the ratio between extensional and torsional moduli, the Fouriernumber, and the dimensionless thermal relaxation. The behavior of the solutions is discussedfrom two perspectives with an asymptotic-numerical approach: (1) the effect of thermal relaxationon the elastic wave celerities, and (2) the effect of thermoelastic coupling on the thermal wavecelerities. With small wavenumbers, the adiabatic solution for Fourier helical strands is recovered.However, with large wavenumbers, the solutions behave differently depending on the thermalrelaxation and chirality. Due to thermoelastic coupling, the thermal wave celerity deviates from theclassical result of the speed of second sound.

Condensing Effect of Suction Slot in Compact-Siro Spinning on Fiber Strands

Compact-siro spinning is a new kind of spinning technique which combines compact spinning and siro spinning,and widely put into practice. Based on the airflow data in the condensing zone,it builds the geometrical model of fiber strands,and then the trajectory of single fiber can be got. The difference of trajectory and compact effect of fibers strands is also analyzed in the condensing zone of three different suction slots. By comparing with the data of three different suction slots,it selects the compact-siro spinning suction device whose yarn has the best overall performance. The theory analysis gives foundation and explanation for experiment,and also provides theoretical basis for optimizing the properties of compactsiro yarn in production practice.

Temperature Dependence of Ultrasonic Longitudinal Guided Wave Propagation in Long Range Steel Strands

Ultrasonic guided wave inspection is an effective non-destructive testing method which can be used for stress level evaluation in steel strands.Unfortunately the propagation velocity of ultrasonic guided waves changes due to temperature shift making the prestress measurement of steel strands inaccurate and even sometimes impossible.In the course of solving the problem,this paper reports on quantitative research on the temperature dependence of ultrasonic longitudinal guided wave propagation in long range steel strands.In order to achieve the generation and reception of a chosen longitudinal mode in a steel strand with a helical shaped surface,a new type of magnetostrictive transducer was developed,characterized by a group of thin clips and three identical permanent magnets.Excitation and reception of ultrasonic guided waves in a steel strand were performed experimentally.Experimental results shows that in the temperature range from-4 ℃ to 34 ℃,the propagation velocity of the L（0,1） mode at 160 kHz linearly decreased with increasing temperature and its temperature dependent coefficient was 0.90（m·s-1 ·（℃）-1） which is very close to the theoretical prediction.The effect of dimension deviation between the helical and center wires and the effect of the thermal expansion of the steel strand on ultrasonic longitudinal guided wave propagation were also analyzed.It was found that these effects could be ignored compared with the change in the material mechanical properties of the steel strands due to temperature shift.It was also observed that the longitudinal guided wave mode was somewhat more sensitive to temperature changes compared with conventional ultrasonic waves theoretically.Therefore,it is considered that the temperature effect on ultrasonic longitudinal guided wave propagation in order to improve the accuracy of stress measurement in prestressed steel strands.Quantitative research on the temperature dependence of ultrasonic guided wave propagation in steel strands provides an important basis for the compensation of temperature effects in stress measurement in steel strands by using ultrasonic guided wave inspection.

Placement of ^(125)I seed strands and stents for a type Ⅳ Klatskin tumor

Herein,we report a new technique that consists of placing two 125 I seed strands and two stents in the right and left intrahepatic bile ducts for the treatment of hilar cholangiocarcinoma.A 75-year-old man presented with jaundice and was diagnosed with Bismuth type Ⅳ Klatskin tumor.Abdominal computed tomography(CT) showed intrahepatic and extrahepatic bile ductdilatation and a soft tissue mass in the hepatic hilum.Because curative surgical resection was not possible,we placed 125 I seed strands and stents in the right and left intrahepatic bile ducts.Three months later,abdominal CT showed less intrahepatic and extrahepatic bile duct dilatation than before the procedure.This technique was feasible and could be considered for the treatment of patients with Bismuth type Ⅳ tumors.

PROPAGATION CHARACTERISTICS OF HIGH ORDER LONGITUDINAL MODES IN STEEL STRANDS AND THEIR APPLICATIONS

Propagation characteristics of high order longitudinal modes of ultrasonic guided waves in seven-wire steel strands are investigated theoretically and experimentally. According to these analysis results, proper longitudinal modes are selected for defect detection in steel strands. Dispersion curves for helical and central wires in a 17.80 mm nominal diameter seven-wire steel strand are numerically obtained firstly, and propagation characteristics of high-order longitudinal modes, such as wave structures, attenuation and dispersion, are analyzed. In experiments, the signals of ultrasonic guided wave at different high frequencies are excited and received at one end of a steel strand by using the same single piezoelectric transducer. The identification of longitudinal modes in the received signals is achieved based on short time Fourier transform. Furthermore, appropriate L（0, 5） mode at 2.54 MHz is chosen for detecting an artificial defect in a helical wire of the steel strand. Results show that high order longitudinal modes in a high frequency range with low dispersion and attenuation whose energy propagates mainly in the center of the wires can be used for defect detection in long range steel strands.

Stress Analysis of Wire Strands by Mesoscale Mechanics

Steel wire ropes have wide application in a variety of engineering fields such as ocean engineering and civil engineering.The stress calculation for steel wire ropes is of crucial importance when conducting strength and fatigue analyses.In this study,we performed a finite element analysis of single-strand steel wire ropes.For the geometric modeling,we used an analytic geometry of space method.We established helical line equations and used the coordinates of the contact points.The finite-element model was simplified using the periodic law.Periodic boundary conditions were used to simulate a wire strand of infinite length under tensile strain,for which we calculated the cross-sectional stresses and inner forces.The results showed that bending and torsion moments emerged when the wire strand was under tensile load.In some cases,the bending stress reached 18%of the tensile stress,and the torsion stress reached 29%of the tensile stress,which means that the total stress was higher than the nominal stress.Whereas in ear-lier studies,a conservative prediction of nominal stress was not possible,the results of our strength and fatigue analyses were more conservative.

ELASTIC DEFORMATION ANALYSIS OF MULTILA YERED STRANDS

This paper describes a general model for the mechanical behavior studying of general wire rope strand. An exact solution of the deformation characteristics was given when the strands is under tensile and torsional loads. The theoretical results are useful in evaluating the extensional and torsional moduli of rigidity for the strands. Finally, a simple design criterion is establised for the nonrotating ropes.

Development on the research of circulating current of generator stator bar strands

From the beginning of 1970’s,the research work onstrand current distribution in hydro-generator statorbars has been made marked progress in China.In order to know whythe generator bar insulations were broken down so often both in op-eration and in testing after the generators being put into operation for8-10 years at Xinanjiang Hydropower Station.Investigations wereconducted and the results of field measurement showed that

Elevated temperature creep model of parallel wire strands

T Parallel wire strands(PWSs),which are widely used in prestressed steel structures,are typically in highstress states.Under fire conditions,significant creep effects occur,reducing the prestress and influencing the mechanical behavior of PWSs.As there is no existing approach to analyze their creep behavior,this study experimentally investigated the elevated temperature creep model of PWSs.A charge-coupled camera system was incorporated to accurately obtain the deformation of the specimen during the elevated temperature creep test.It was concluded that the temperature level had a more significant effect on the creep strain than the stress level,and 450℃ was the key segment point where the creep rate varied significantly.By comparing the elevated temperature creep test results for PWSs and steel strands,it was found that the creep strain of PWSs was lower than that of steel strands at the same temperature and stress levels.The parameters in the general empirical formula,the Bailey–Norton model,and the composite timehardening model were fitted based on the experimental results.By evaluating the accuracy and form of the models,the composite time-hardening model,which can simultaneously consider temperature,stress,and time,is recommended for use in the fire-resistance design of pre-tensioned structures with PWSs.

Experimental investigation of axial tensile and fatigue behaviors of HTS round strands

For the development of high‐temperature superconducting(HTS)magnet systems of future fusion devices,a novel HTS round strand based on a stacking structure was designed and manufactured using second generation(2G)HTS tapes.Different mechanical loads during operation can result in irreversible degradation of the strand.The axial tension and fatigue loads need particular attention.Therefore,it is important to investigate the electromechanical behavior of the round strand under various axial tension and cyclic loads.In this paper,the axial tensile and fatigue tests were conducted at 77 K,self‐field.Taking 95%critical current(I_(c))retention as the criterion,the results of the tensile tests revealed that the average tensile stress and strain were as high as 344 MPa and 0.47%,respectively.Fatigue characteristics were also investigated as a function of axial tensile stress.No significant performance degradation was observed up to 100,000 loading cycles with stress amplitudes ranging from 20 MPa to 200 MPa.Ic degradation occurs after 16,000 loading cycles with 380 MPa as the maximum stress.Furthermore,the microscopic defects of the round strand samples due to fabrication imperfections and mechanical loading were investigated using metallographic microscope and scanning electron microscope.These results presented in this paper are useful for comprehending and improving the mechanical behaviors of the strand in high‐field and large‐scale fusion magnet systems.

Mechanical characterization of a 10-MJ HTS SMES magnet wound by quasiisotropic strands and directly stacked tape conductors

A 10‐MJ‐class superconducting magnetic energy storage(SMES)magnet is designed and optimized in this study using quasi‐isotropic strands and stacked‐tape conductors.In order to ensure the stable operation of SMES systems,it is necessary to evaluate the mechanical properties risk caused by the Lorentz force.Therefore,in this study,the magnetic stress caused by the Lorentz force is analyzed using the finite element method.The results show that the tapes near the inner diameter of the magnet are subjected to a higher stress and require considerable support.Although the maximum stress is increased by two times due to the presence of the screening current,it is within the safety range.The screening current does not vanish after the discharge process.After discharge,the coil is still subjected to a stress on the other of a few MPa.

Optimization of large capacity six-strand tundish with flow channel for adapting situation of fewer strands casting

Closing a single nozzle or multiple nozzles for a temporary casting operation(fewer strands casting)was common in a tundish due to insufficient molten steel or equipment failure.However,nozzle clogging usually happens under the situation of fewer strands casting.Hence,a temperature deviation index was introduced to characterize the temperature stratification of molten steel for a large capacity tundish,and a new calculation method of residence time curve was used to describe the different flow types of molten steel at each outlet.Based on hydraulics experiment and numerical simulation,important parameters of present case and modified case were compared.Under the situation of fewer strands casting,the proportion of internal-recycle flow after modification decreased from 30.68%to 24.55%;the standard deviation of the response time reduced from 27.59 to 13.16,and the interquartile range of temperature deviation index changed from 0.89 to 0.27.

Representation of A15 composition and T_C in internal-Sn Nb_3Sn superconducting strands

Four sets of mono-element (ME) and two kinds of multifilament (MF) internal-Sn Nb3Sn superconducting strands were designed and fabricated through RRP method in which different compoment ratios, various composite configurations and some third element alloying were arranged. All the strand samples underwent a 210°C/50 h + 340°C/25 h thermal duration for Cu-Sn alloying. After that A15 phase formation heat treatment (HT) was applied for which the ME samples were chosen at three reaction temperatures of 675°C, 700°C and 725°C for 100 h and 200 h while the MF samples at four temperatures of 650°C, 675°C, 700°C and 725°C for 128 h and 200 h. The heat-treated samples were examined for A15 phase composition distribution by X-ray EDS. SQUID magnetization measurement was used to determine critical temperature TC. The obtained results demonstrate that for fully-reacted internal-Sn Nb3Sn superconductors the A15 phase composition and the intrinsic property TC are determined by the diffusion and solid state reaction mechanism and are independent of the factors including HT temperature, strand composite component and configuration arrangement, and the third element addition within the experimental range.

Hepatitis C Virus RNA Strands Detection in Peripheral Blood Mononuclear Cells Legitimizes Virus Eradication in Negative Serum PCR Naive and Post-treatment Patients

Background and Aims:Hepatitis C virus(HCV)hepatotropism is associated with intra-peripheral blood mononuclear cell(PBMC)infection that causes post-treatment relapse in RNA seronegative patients.Our understanding of the association of non-viremic hepatic fibrosis with positive anti-HCV IgG antibodies and active hepatocellular damage might be increased by PBMCs screening for intracellular infection.Thus,the goals of this study included evaluation of PBMCs PCR for diagnosing HCV infection,addressing PBMCs plus serum real-time(SRT)PCR benefits over SRT-PCR alone,studying intraPBMCs distribution of RNA sense and antisense strands,and identifying treatment feasibility in solitary intracellular infection.Methods:Enzyme-linked immunosorbent assay,SRT-PCR and PBMCs PCR were used to evaluate HCV infection in 401 subjects.The patients were classified into groups of negative controls(n=30),positive controls(n=63),non-viremia post-treatment(experienced;n=166)and na(i)ve(n=49)cases,and non-viremia positive PBMCs PCR na(i)ve(n=35)and experienced(n=58)patients.Results:The diagnosis of true positive and negative by PBMCs PCR and SRT-PCR had 100%and 96.7%compatibility respectively.PBMCs PCR detected intracellular HCV infection in 49 out of 215 non-viremia patients;among them,na(i)ve cirrhotics had significantly higher number of intracellular infection than the na(i)ve non-cirrhotic(P<0.001)and experienced patients(P<0.0001).Antisense and sense strands were respectively recognized in na(i)ve and experienced cases(P=0.01218).Intracellular HCV strands were detected in 18.02%of experienced patients.Recognition of intracellular RNA strands showed significant decline in experienced compared to na(i)ve patients(P<0.05).Conclusion:PBMCs PCR is a valid diagnostic test that can diagnose intracellular HCV when SRT-PCR is negative.Antisense and sense strands are respectively recognized more often in na(i)ve and experienced patients.The expected overall relapsing rate in our cohort was 18.02%.IntraPBMC infections are associated with liver cirrhosis in na(i)ve non-viremia patients.Eradication of intracellular strands is recommended to avoid RNA seroconversion.

Analysis on the causes of massive stranding of Yellow Sea green tide on Lianyungang and Rizhao coasts in 2022

In 2022,Yellow Sea green tide caused by Ulva prolifera reached a historic minimum and the coastal areas of Shandong Peninsula were less affected.However,the largest amount of seaweed biomass has been washed ashore on Lianyungang and Rizhao coasts since 2015.We studied the development pattern of Yellow Sea green tide in 2022,and analyzed the key environmental factors on the growth and drifting,then discussed the possible reasons that resulted in the massive stranding of green tide biomass in Lianyungang and Rizhao.Results show under the combined influence of the east to southeast winds and currents with shoreward anomalies,green tide drifted to the coastal waters between Shandong and Jiangsu provinces and the distribution areas located westward compared with previous years(2008–2021).Floating U.prolifera rafts from the coastal waters of Binhai and Sheyang drifted continuously into the coastal waters of Lianyungang and Rizhao,providing important supplements for Yellow Sea green tide.Because green tide in 2022 distributed close to the coastal waters,the abundant nutrients might support their continuous high growth rate.In addition,the amount of rainfall around Shandong Peninsula from late June to early July were significantly higher than in previous years,which might promote the development of green tide to some extent.

Partial strands synthesizing leads to inevitable aborting and complicated products in consecutive polymerase chain reactions (PCRs)

Various abnormal phenomena have been observed during PCR so far. The present study performed a series of consecutive PCRs (including many rounds of re-amplification continuously) and found that the abortion of re-amplification was inevitable as long as a variety of complicated product appeared. The aborting stages varied, according to the lengths of targets. Longer targets reached the abortion earlier than the shorter ones, marked by appearance of the complex that was immobile in electropho-resis. Denatured gel-electrophoresis revealed that the complex was mainly made up of shorter or partially synthesized strands, together with small amounts of full-length ones. Able to be digested by S1 nuclease but unable by restriction endonucleases (REs), the complex was proved to consist of both single regions and double-helix regions that kept the complex stable thermodynamically. Simulations gave evidence that partial strands, even at lower concentration, could disturb re-amplification effec- tively and lead to the abortion of re-amplifications finally. It was pointed out that the partial strands formed chiefly via polymerase’s infidelity, and hence the solution to lighten the abnormality was also proposed.

A Theoretical Model for Characterizing the Internal Contact of the CICC Strands under Axial Strain

A theoretical model is proposed to calculate the internal contact distributions and contact forces of a 3×4×4×4 twisted NbSn cable under applied axial strain.The critical current density reduction of the whole cable can be calculated.The thin rod theory is employed to analyze the mechanical behavior of each strand.According to the regular helical structure,the contact distribution of each strand is obtained,and the contact force in the cable is analyzed.At last,a prediction about the critical current density of the twisted cable is made.The results show that decreasing the pitch length can reduce the contact forces between strands.

Research progress and prospects of nucleic acid isothermal amplification technology

Nucleic acid(DNA and RNA)detection and quantification methods play vital roles in molecular biology.With the development of molecular biology,isothermal amplification of DNA/RNA,as a new molecular biology technology,can be amplified under isothermal condition,it has the advantages of high sensitivity,high specificity,and high efficiency,and has been applied in various fields of biotechnology,including disease diagnosis,pathogen detection,food hygiene and safety detection and so on.This paper introduces the progress of isothermal amplification technology,including rolling circle amplification(RCA),nucleic acid sequence-dependent amplification(NASBA),strand displacement amplification(SDA),loop-mediated isothermal amplification(LAMP),helicase-dependent amplification(HDA),recombinase polymerase amplification(RPA),cross-priming amplification(CPA),and its principle,advantages and disadvantages,and application development are briefly summarized.

A method for calculating strand tension in the anchor span of a suspension bridge considering the rotation of a splay saddle

This paper reports a method for strand tension in anchor spans considering rotation.A kind of co-moved coordinate system,a saddle local coordinate system,was set up.This system implemented the rotation of the splay saddle through the rotation of the coordinate system,and all calculations proceeded in this coordinate system.Considering the rotation of the anchoring surface by the rotation of the local coordinate system of the anchoring surface,the anchorage point coordinates of strands were transformed to the local sadle coordinate system.There was a two-layer iteration adopted in the calculation.In the inner iteration,the cable force at the end of the vertical bend was taken as the variable,and the ordinate of the anchorage point was taken as the target value.In the outer iteration,the vertical tangential angle at the end of the vertical bend was taken as the variable,and the ordinate of the anchorage point was taken as the target value.The method carried out the rotation of the splay saddle and anchor surface and was simple,convenient and without approximation.The effect of rotation was considered precisely;it showed stability during the process of two-layer iteration,powerful adaptation and higher efficiency and had been successfully applied in the construction control of the Wufengshan Yangtze River Bridge,the world's first kilometer-level combined highway and railway suspension bridge.

基于Strand7软件分析预应力锚索间距改变对加固边坡稳定性的影响

无粘结预应力锚索抗滑桩在边坡工程中应用广泛,但是在施工锚索抗滑桩时常常遇到一些问题,本文针对预应力锚索间距变化对加固边坡影响进行分析研究,简要阐述了无粘结预应力锚索抗滑桩工作机理、施工方法和施工要点,在施工过程中改变预应力锚索间距时常发生,通过有限元软件Strand7分析其间距改变对边坡稳定性的影响,从而合理控制锚索间距并指导现场施工。