Clamp Structure Research Articles

Semi-analytical dynamic modeling of parallel pipeline considering soft nonlinearity of clamp: A simulation and experimental study

Clamp is a crucial support structure to secure and connect the parallel pipeline system. Since the metal felt of the clamp is composed of metal rubber material, as well as the clamp structure using bolted connections, clamp is prone to cause nonlinear force during vibration. Nevertheless, no relevant paper has been reported to study the influence of soft nonlinearity of clamps on parallel pipelines. To bridge this gap, the present study introduces a novel semi-analytical dynamic model that effectively considers the influences of nonlinear clamps in parallel pipeline systems. The proposed model simulates the clamp's vertical hysteretic restoring force using the Bouc-Wen model. The clamp parameters are identified using Particle Swarm Optimization (PSO) with experimental and simulation errors as the objective function. Subsequently, the model is then validated by conducting modal and response tests. The numerical results are consistent with the experimental results. In order to prove the validation of the proposed model, experiments are conducted using dual clamps at different positions, and it can be observed that the nonlinear parameters of the clamps still meet the accuracy requirements. Moreover, the influences of fluid parameters on frequency are compared with the ANSYS software and the proposed model, and the influence trends exhibit consistency. By considering the nonlinear effects of clamps, the proposed model facilitates enhanced accuracy in predicting vibration responses.

Nonlinear dynamics of viscoelastic fluid-conveying pipe installed within uniform external cross flow by pipe clamps

Nonlinear dynamic response of a viscoelastic fluid-conveying pipe excited by uniform external cross flow is investigated, which is installed by pipe clamps. A pipe clamp theoretical model is proposed for the actual pipe clamp instead of the commonly used simply supported or clamped boundary conditions. Based on the model, equivalent support stiffness and torsional stiffness are obtained from structure and material parameters of the pipe clamp. The vortex-induced lift force and the mean drag force are described by van der Pol oscillator model. The nonlinear equations of motion with the boundary conditions of different constraint stiffness are discretized by Differential Quadrature Method (DQM) and then solved by Runge-Kutta algorithm. The results are verified by Galerkin method for the pinned-pinned pipe, and by ANSYS for the pipe with two arbitrary constraint stiffnesses. The dependence of critical external fluid velocity upon constraint stiffness and pipe length is investigated. Moreover, the effects of support stiffness, torsional stiffness, internal fluid velocity, and viscoelastic coefficient on the amplitude response of the pipe are studied in detail. The influence of constraint stiffness on characteristics of lock-in region is elucidated. Consequently, pipe clamp spacing, material and structure parameters of the rubber mat can be designed to ensure the requirement of economy and safety, which are helpful to guide the layout and design of pipe clamps.

Differential Power Processing Converter With Active Clamp Structure and Integrated Planar Transformer for Power Generation Optimization of Multiple Photovoltaic Submodules

In recent years, in order to improve the fuel efficiency of electric vehicles, a lot of research has been conducted to adopt photovoltaic (PV) systems to electric vehicles. In addition, various Differential Power Processing (DPP) converters that can mitigate power imbalance among submodules in PV systems are being studied and developed. However, most conventional DPP converters suffer from large volume, low-price competitiveness, and low efficiency. Therefore, in this paper proposes a novel DPP converter. The proposed DPP converter can significantly reduce the volume of converter by integrating multiple transformers into single transformer. Moreover, because of the active clamp structure, it is possible to eliminate secondary side circuits. Furthermore, more than 95% efficiency under 10-60% load and maximum 96.654% efficiency about 20% load were achieved. Thus, the proposed DPP converter can achieve high power density, high price competitiveness, as well as high efficiency. To support the validity of the proposed converter, a prototype of the proposed DPP converter was built, and experiments were proceeded with 8V input and 60W/30V output specifications.

Design of Backup Protective Hardware for Suspension Clamp of Electric Power Overhead Ground Wire

Aiming at the disconnection problem of power overhead ground wire caused by wind vibration or the action of power frequency short-circuit current, the newly revised “Eighteen major anti-accident measures of State Grid Corporation China” proposes that independent double string structure should be adopted in suspension clamp of overhead ground wire. Based on this, a research scheme of backup protective hardware for the suspension clamp of the overhead ground wire of the power transmission line is proposed. In this scheme, the backup protective hardware for the suspension clamp is designed and added on the premise that the original overhead ground wire-suspension clamp structure is not changed. It provides backup measures for the original suspension clamp and reduces suspension clamp heating by an electrical shunt. Finally, the mechanical failure load test and salt spray test are performed on the designed production. The results show that the designed production meets the standard and could be used in actual engineering. At the same time, the practical engineering application shows that the backup protective hardware can effectively reinforce the ground wire suspension clamp with double strings, avoiding the problem of dropping and breaking after the original clamp is broken.

Pipeline Vibration Control Using Magnetorheological Damping Clamps under Fuzzy-PID Control Algorithm.

Aiming at the problem of low-frequency vibration of the hydraulic pipeline, a new type of semi-active damping magnetorheological (MR) damping clamp structure is designed. The structure size and material of the MR damping clamp were determined. The control model of the vibration damping system was established, and the control method combining fuzzy control and Proportional-Integral-Derivative (PID) control was used to carry out the numerical simulation, which proved that the fuzzy–PID control algorithm is effective and stable. The results show that the MR damping clamp proposed in this paper can effectively suppress the axial displacement and acceleration of the hydraulic pipeline in the excitation frequency range of 1 Hz~10 Hz. This research provides a new technical approach for low-frequency vibration control of hydraulic pipelines.

Fission yeast Rad8/HLTF facilitates Rad52-dependent chromosomal rearrangements through PCNA lysine 107 ubiquitination.

Gross chromosomal rearrangements (GCRs), including translocation, deletion, and inversion, can cause cell death and genetic diseases such as cancer in multicellular organisms. Rad51, a DNA strand exchange protein, suppresses GCRs by repairing spontaneous DNA damage through a conservative way of homologous recombination, gene conversion. On the other hand, Rad52 that catalyzes single-strand annealing (SSA) causes GCRs using homologous sequences. However, the detailed mechanism of Rad52-dependent GCRs remains unclear. Here, we provide genetic evidence that fission yeast Rad8/HLTF facilitates Rad52-dependent GCRs through the ubiquitination of lysine 107 (K107) of PCNA, a DNA sliding clamp. In rad51Δ cells, loss of Rad8 eliminated 75% of the isochromosomes resulting from centromere inverted repeat recombination, showing that Rad8 is essential for the formation of the majority of isochromosomes in rad51Δ cells. Rad8 HIRAN and RING finger mutations reduced GCRs, suggesting that Rad8 facilitates GCRs through 3’ DNA-end binding and ubiquitin ligase activity. Mms2 and Ubc4 but not Ubc13 ubiquitin-conjugating enzymes were required for GCRs. Consistent with this, mutating PCNA K107 rather than the well-studied PCNA K164 reduced GCRs. Rad8-dependent PCNA K107 ubiquitination facilitates Rad52-dependent GCRs, as PCNA K107R, rad8, and rad52 mutations epistatically reduced GCRs. In contrast to GCRs, PCNA K107R did not significantly change gene conversion rates, suggesting a specific role of PCNA K107 ubiquitination in GCRs. PCNA K107R enhanced temperature-sensitive growth defects of DNA ligase I cdc17-K42 mutant, implying that PCNA K107 ubiquitination occurs when Okazaki fragment maturation fails. Remarkably, K107 is located at the interface between PCNA subunits, and an interface mutation D150E bypassed the requirement of PCNA K107 and Rad8 ubiquitin ligase for GCRs. These data suggest that Rad8-dependent PCNA K107 ubiquitination facilitates Rad52-dependent GCRs by changing the PCNA clamp structure.

A new magnetron driving method using a phase‐shifted active clamp forward converter for sulfur plasma tube applications

This paper presents a new method for driving the magnetron for a sulfur plasma tube using the two-switch forward converter structure with a phase-shifting active clamp (1000±40 W, 285 mA, 4 kV). Depending on the output voltage level required, the magnetron driver circuit is boosted and insulated and also has high gain. The use of the two-switch forward converter reduces the transistor voltage stress. In addition, applying the clamp structure balances the magnetization current. Besides, by controlling the phase shift of the clamp transistor, while maintaining the magnetic current balance of the power transformer, the duty cycle of the main transistors can be increased. This allows more voltage level transfer to the secondary winding of the transformer. Therefore, with a fixed transformer core, more voltage transmission is possible in comparison with a conventional forward converter. Moreover, using the PFC converter improves the power factor and stabilizes the DC-link voltage. The magnetron driver circuit provides a maximum power of 1 kW with an average power of 125–250 W by adjusting the converter's active time under minimum loss conditions. The magnetron driver circuit provided is validated by the simulation and experimental results.

Development of a noise elimination electrical impedance spectroscopy (neEIS) system for single cell identification

We propose a noise elimination electrical impedance spectroscopy (neEIS) system for single cell identification whose characteristics are cell-free clamp structure and cell-position independent calibration. The function of the cell-free clamp structure is to enable a single cell to be freely located into neEIS system. The cell-position independent calibration consists of three steps; impedance measurement, electrode cell constant calculation, and single cell dielectric properties estimation. The cell-position independent calibration enables elimination the influence of noise associated with ions as well as electrical double layer during the measurement process. We demonstrate an application of neEIS system to discriminate three types of MRC-5 human lung fibroblasts; wild type (WT), GFP-fused histone (HT) modification, and GFP transfected (GFPT) MRC-5 cells suspended in a sucrose medium. To further evaluate the neEIS system, we simulated the electrical potential distribution and root means square error of single cell dielectric properties numerically. As a result, we obtained electric potential distribution which clearly characterized the internal change of single cell components. Moreover, we determined that the neEIS system is capable of accurate single cell identification after noises elimination with less than 1.05% average root means square error. Taken together, these results demonstrate that the proposed neEIS system has the potential to improve the performance of biosensors. Thus, this study will bring a new insight into the development of a biosensor system for high accuracy single cell identification as well as inspire the development of a diagnostic device for early fetal lung diseases based on the neEIS system.

Reliability Analysis of Clamp Welding Defects Based on Finite Element Simulation

Cracking and failure of clamp is a common problem in the maintenance of power grid, which seriously threatens the safety of power grid electrical transmission. Therefore, based on the finite element analysis method, the static strength check and reliability analysis are firstly carried out to evaluate the structural safety of the defect-free clamp. Secondly, SINTAP was used to evaluate clamps with planar defects, and Paris formula was used to predict the fatigue crack growth life. The results show that the clamp with planar welding defects can also meet the requirements under severe working conditions due to its good plastic reserve and toughness. The crack depth a of the welding defect significantly affects the safety of the clamp structure, and the crack feature a/c also has a certain impact on the safety. However, when the crack depth a is less than a certain value, no fatigue fracture will occur.

Redescription and molecular characterisation of Allogastrocotyle bivaginalis Nasir & Fuentes Zambrano, 1983 (Monogenea: Gastrocotylidae) from Trachurus picturatus (Bowdich) (Perciformes: Carangidae) off the Algerian coast, Mediterranean Sea.

Allogastrocotyle bivaginalis Nasir & Fuentes Zambrano, 1983, the sole species of Allogastrocotyle Nasir & Fuentes Zambrano, 1983, was described from Trachurus lathami Nichols off Venezuela and never recorded since. We found monogeneans on Trachurus picturatus (Bowdich) (Carangidae) off the Algerian coast, Mediterranean Sea, which had the characteristics of the genus, including, especially, paired vaginae. We compared them to the single available specimen of A. bivaginalis, the holotype. Unfortunately, this holotype does not show clamp structure and soft internal anatomy. Our specimens were similar to A. bivaginalis in most characteristics such as body shape, vaginal openings, and number of testes, clamps and hooks in genital atrium. We detected minor differences in clamp structure but could not ascertain if these were the result of incomplete observations in the original description of real morphological differences. The host fish of our specimens were barcoded (cox1) confirming their specific identity. A phylogenetic analysis of cox1 sequences showed that our sequences of A. bivaginalis were distinct from those of Pseudaxine trachuri Parona & Perugia, 1889 (distance > 15%) and of several other gastrocotylids. Finally, we could not distinguish our Mediterranean specimens from A. bivaginalis, neither on the base of morphology (because the original description is incomplete) nor on molecules (because molecular information is lacking on A. bivaginalis from Venezuela) and ascribe them to A. bivaginalis. However, hosts are different, and localities are widely separated, so it is likely that future study will show that the species from the Mediterranean is a distinct, new, species.

Ultrasonic Imaging Detection of Strain Clamp Hydraulic Crimping Quality on Transmission Line

Strain clamp plays an important part for the transmission line. It is also a weak link part of the aluminum conductor steel reinforced (ACSR). By analyzing the strain clamp structure, the aluminum tube acts as a bridge and the force of the aluminum tube and the steel anchor is the same as that of the ACSR. The hydraulic crimping quality of the strain clamp determines the safety and reliability of the transmission line. Ultrasonic imaging detection has the advantages of safety, reliability and high detection efficiency. In this paper, ultrasonic phased array and ultrasonic B pulse echo methods are used to measure the crimping quality of the strain clamp. The ultrasonic phased array can display the crimping quality of the strain clamp directly without moving the focusing probe. The ultrasonic B pulse echo image shows the crimping quality of the strain clamp for two regions.

Application of Pre-stranded Tensile Clamp for Aluminum Composite Carbon Fiber Core

The growth of electricity demand has put forward higher requirements for transmission line performance. Aluminum composite carbon fiber cores (ACCC) has better performance than traditional steel core aluminum conductor and can better meet the requirements of power transmission and transformation field. However, at present, the wedge-shaped self-locking tension clamp is usually used for aluminum composite carbon fiber cores, which is complicated in construction technology and poor in economy, which restricts the promotion and application of aluminum composite carbon fiber cores.In order to solve the above problems, three kinds of tension clamp structures applied to different specifications of aluminum conductors composite core are optimized. Through the strength and grip test of the clamp, it is verified that the grip force of the clamp structure designed can reach 95% of the rated tensile strength of the conductor. Finally, through the comparative analysis of construction and installation, it is concluded that the pre-twisted tension wire clamp designed has a good economic effect.

Terbium(III) Modified Fluorescent Carbon Dots for Highly Selective and Sensitive Ratiometry of Stringent.

Highly selective and sensitive detection of guanosine 3'-diphosphate-5'-diphosphate (ppGpp), namely, the stringent in plants or microorganisms responding to strict or extreme environmental conditions such as stress and starvation, which plays an important role in gene expression, rRNA and antibiotics production, regulations of virulence of bacteria, and growth of plants, faces a great challenge owing to its extreme similarity to normal nucleotides. By modifying the surface groups of a facile two-step hydrothermal route prepared carbon dots (CDs) with terbium ions (Tb3+) in this contribution, a novel fluorescent probe with excellent properties such as highly physical and chemical stability, narrow emission and excitation wavelength-independent emission was prepared. The Tb3+ ions on the surface of CDs cannot only preserve the intrinsic fluorescence (FL) of CDs but also keep its own coordination capacity with rare earth complex, and thus the clamp structure (four phosphate groups) of ppGpp can specific binding with Tb3+ ions on the surface of CDs to produce antenna effect. Therefore, a highly selective and sensitive fluorescent ratiometry of ppGpp was developed by terbium-modified carbon dots (CDs-Tb) with the limit of detection as low as 50 nM based on the synergistic effect of antenna effect of Tb3+ ions and specific recognition capacity of CDs. The applicability of this assay was demonstrated by CDs-Tb-based paper sensor for high distinguishing ppGpp from other nucleotides with similar structure.

Structural insights into drug development strategy targeting EGFR T790M/C797S.

Treatment of non-small-cell lung cancers (NSCLCs) harboring primary EGFR oncogenic mutations such as L858R and exon 19 deletion delE746_A750 (Del-19) using gefitinib/erlotinib ultimately fails due to the emergence of T790M mutation. Though WZ4002/CO-1686/AZD9291 are effective in overcoming EGFR T790M by targeting Cys797 via covalent bonding, their efficacy is again limited due to the emergence of C797S mutation. New agents effectively inhibiting EGFR T790M without covalent linkage through Cys 797 may solve this problem. We presented here crystal structures of EGFR activating/drug-resistant mutants in complex with a panel of reversible inhibitors along with mutagenesis and enzyme kinetic data. These data revealed a previously un-described hydrophobic clamp structure in the EGFR kinase which may be exploited to facilitate development of next generation drugs targeting EGFR T790M with or without concomitant C797S. Interestingly, mutations in the hydrophobic clamp that hinder drug binding often also weaken ATP binding and/or abolish kinase activity, thus do not readily result in resistance to the drugs.

A low-voltage sense amplifier with two-stage operational amplifier clamping for flash memory**Project supported by the National Natural Science Fundation of China (No. 61376028).

A low-voltage sense amplifier with reference current generator utilizing two-stage operational amplifier clamp structure for flash memory is presented in this paper, capable of operating with minimum supply voltage at 1 V. A new reference current generation circuit composed of a reference cell and a two-stage operational amplifier clamping the drain pole of the reference cell is used to generate the reference current, which avoids the threshold limitation caused by current mirror transistor in the traditional sense amplifier. A novel reference voltage generation circuit using dummy bit-line structure without pull-down current is also adopted, which not only improves the sense window enhancing read precision but also saves power consumption. The sense amplifier was implemented in a flash realized in 90 nm flash technology. Experimental results show the access time is 14.7 ns with power supply of 1.2 V and slow corner at 125 °C.

Sliding Clamp of DNA Polymerase III as a Drug Target for TB Therapy: Comprehensive Conformational and Binding Analysis from Molecular Dynamic Simulations.

Tuberculosis, caused by Mycobacterium tuberculosis, is one of the most common causes of death in the world. Mycobacterium tuberculosis -sliding clamp is a protein essential for many important DNA transactions including replication and DNA repair proteins, thus, a potential drug target for tuberculosis. Further investigation is needed in understanding DNA polymerase sliding clamp structure, especially from a computational perspective. In this study, we employ a wide-range of comparative molecular dynamic analyses on two systems: Mycobacterium tuberculosis - sliding clamp enzyme in its apo and bound form. The results reported in this study shows apo conformation to be less stable, as compared to bound conformation with an average radius of gyration of 25.812 and 25.459 Å, respectively. This was further supported by root mean square fluctuation, where an apo enzyme showed a higher degree of flexibility. However, the presence of the ligand lowers radius of gyration and root mean square fluctuation and also leads to an existence of negative correlated motions. Principal component analysis further justifies the same findings, whereby the apo enzyme exhibits a higher fluctuation compared to the bound complex. In addition, a stable 310 helix located at the binding site appears to be unstable in the presence of the ligand. Hence, it is possible that the binding of the ligand may have caused a rearrangement of the structure, leading to a change in the unwinding of 310 helix. Findings reported in this study further enhance the understanding of Mycobacterium tuberculosis -DnaN and also give a lead to the development of potent tuberculosis drugs.

Design and Analysis of the Thyristor Clamp Structure in ITER Poloidal Field Converter Unit

Clamp structure is a main part in thyristor installation technique. This paper presents the design and analysis of the thyristor clamp structure for ITER poloidal field converter unit. The clamp structure is designed to provide a mounting force up to 145 kN. Its structural stability is verified by a corresponding simulation and a static test. The contact effect of single side clamp and double side clamp is analyzed and compared, and double side clamp structure is applied in the design. In addition, an extra simulation is performed to study the influence on the contact effect due to unbalanced mounting forces. And a test is also performed. The analysis method and result presented in this paper will be very valuable in the design and analysis of clamp structure used in the converter systems.

Intrinsic stability and oligomerization dynamics of DNA processivity clamps.

Sliding clamps are ring-shaped oligomeric proteins that are essential for processive deoxyribonucleic acid replication. Although crystallographic structures of several clamps have been determined, much less is known about clamp structure and dynamics in solution. Here, we characterized the intrinsic solution stability and oligomerization dynamics of the homodimeric Escherichia coli β and the homotrimeric Saccharomyces cerevisiae proliferating cell nuclear antigen (PCNA) clamps using single-molecule approaches. We show that E. coli β is stable in solution as a closed ring at concentrations three orders of magnitude lower than PCNA. The trimeric structure of PCNA results in slow subunit association rates and is largely responsible for the lower solution stability. Despite this large difference, the intrinsic lifetimes of the rings differ by only one order of magnitude. Our results show that the longer lifetime of the E. coli β dimer is due to more prominent electrostatic interactions that stabilize the subunit interfaces.

Disulfide Linkage and Structure of Highly Stable Yeast-derived Virus-like Particles of Murine Polyomavirus

VP1 is the major coat protein of murine polyomavirus and forms virus-like particles (VLPs) in vitro. VLPs consist of 72 pentameric VP1 subunits held together by a terminal clamp structure that is further stabilized by disulfide bonds and chelation of calcium ions. Yeast-derived VLPs (yVLPs) assemble intracellularly in vivo during recombinant protein production. These in vivo assembled yVLPs differ in several properties from VLPs assembled in vitro from bacterially produced pentamers. We found several intermolecular disulfide linkages in yVLPs involving 5 of the 6 cysteines of VP1 (Cys(115)-Cys(20), Cys(12)-Cys(20), Cys(16)-Cys(16), Cys(12)/ Cys(16)-Cys(115), and Cys(274)-Cys(274)), indicating a highly coordinated disulfide network within the in vivo assembled particles involving the N-terminal region of VP1. Cryoelectron microscopy revealed structured termini not resolved in the published crystal structure of the bacterially expressed VLP that appear to clamp the pentameric subunits together. These structural features are probably the reason for the observed higher stability of in vivo assembled yVLPs compared with in vitro assembled bacterially expressed VLPs as monitored by increased thermal stability, higher resistance to trypsin cleavage, and a higher activation enthalpy of the disassembly reaction. This high stability is decreased following disassembly of yVLPs and subsequent in vitro reassembly, suggesting a role for cellular components in optimal assembly.

Study on the Engine Speed Sensor Position Measuring Tool Based on Minitab

Research on key position speed sensor of automobile engine size measuring tool as an example, for studying the optimization of measuring tools through use the powerful Minitab software statistics, analysis and calculation functions. Randomly selected 10 parts as a measurement sample, then obtained the measurement data by experiment. Analysis of the measured data with Minitab and calculate the repeatability and reproducibility of the device. Find the causes of failure in measuring and explore how to optimize the measuring method. Improved measuring clamp structure, and through experiments verify its feasibility. Thereby solving the problem of measuring failure to ensure the accuracy of measurement data, and improve the measurement accuracy of the product.