Tension Rod Research Articles

Mechanics of microtubules

Microtubules are rigid cytoskeletal filaments, and their mechanics affect cell morphology and cellular processes. For instance, microtubules for the support structures for extended morphologies, such as axons and cilia. Further, microtubules act as tension rods to pull apart chromosomes during cellular division. Unlike other cytoskeletal filaments (e.g., actin) that work as large networks, microtubules work individually or in small groups, so their individual mechanical properties are quite important to their cellular function. In this review, we explore the past work on the mechanics of individual microtubules, which have been studied for over a quarter of a century. We also present some prospective on future endeavors to determine the molecular mechanisms that control microtubule rigidity.

SU‐FF‐I‐32: Profile and Exposure Measurements in Axial and Helical Multi‐Slice Computed Tomography

Purpose: To investigate why organ doses for helical computed tomography (CT) scans were found to be up to 25% less than similar axial scans. The organ dose measurements were performed previously using thermoluminescent point dosimeters (TLD) in a pediatric phantom. Method and Materials: Tension rods were placed across the bore of the CT scanners, flanking the scan region, in order to support measurement devices without relying on the patient table which moves during helical scans. Under this configuration, the table was kept out of the scan region for all measurements. Beam profile measurements were made for 20mm and 40mm beam configurations using computed radiography (CR) plates and software to compute the FWHM of the profile. Exposure measurements were made with a 10cm pencil ion chamber in a 16cm head phantom, similar to standard CTDI measurements. These measurements were made for multiple 64‐channel CT scanners in both axial and helical modes. For the exposure measurements, multiple scan parameters were varied including kVp, focal spot size, field of view, rotation time, exposure time, and pitch. Differences between axial and helical measurement results were compared. Results: Differences in FWHM values for the beam width measurements between axial and helical scan modes were found to be less than 1%. The normalized exposure values between axial and helical scans were found to be less than 1% in general. The only exceptions were caused by differing focal spot sizes and rotation times of less than 1 second, for which the difference was up to 2.5%, but still well within the manufacturer's tolerance. Conclusion: There were no substantial differences between axial and helical scans for the radiation profiles and exposure parameters we examined. Therefore, we conclude that the explanation for the axial/helical point dose differences must lie elsewhere. One possibility might be patient table mechanic.

Assembly and Test of HD2, a 36 mm Bore High Field ${\rm Nb}_{3}{\rm Sn}$ Dipole Magnet

We report on the fabrication, assembly, and test of the Nb3Sn dipole magnet HD2. The magnet, aimed at demonstrating the application of Nb3Sn superconductor in high field accelerator-type dipoles, features a 36 mm clear bore surrounded by block-type coils with tilted ends. The coil design is optimized to minimize geometric harmonics in the aperture and the magnetic peak field on the conductor in the coil ends. The target bore field of 15 T at 4.3 K is consistent with critical current measurements of extracted strands. The coils are horizontally pre-stressed during assembly using an external aluminum shell pre-tensioned with water-pressurized bladders. Axial pre-loading of the coil ends is accomplished through two end plates and four aluminum tension rods. The strain in coil, shell, and rods is monitored with strain gauges during assembly, cool-down and magnet excitation, and compared with 3D finite element computations. Magnet's training performance, quench locations, and ramp-rate dependence are then analysed and discussed.

A Gripper Actuated by a Pair of Differential SMA Springs

This article presents a gripper actuated by a pair of differential shape memory alloy (SMA) springs. The mechanical structure of the gripper includes a pair of fingers, a coupler, a tension rod, a slider, and a frame. An experimental setup of the SMA gripper is established. The SMA actuator is heated by the electric current and cooled by fans. Thermal resistance sensors are used to measure the temperature of the SMA springs and a slide rheostat is used to sense the output displacement of the actuator. In order to evaluate the potential of the SMA actuator for application to the proposed gripper, three types of tests are performed as follows: influence of the cooling methods, heating current, and action frequency on the characteristics of the SMA actuator and the gripper. The experimental results show that the output displacement amplitude can increase by increasing the heating current and decreasing the action frequency. A good cooling method can increase the cyclic output displacement amplitude and the bandwidth of the SMA actuator. A proportional-integral (PI) controller is presented to control the output position of the gripper, and a two-phase control method is developed to reduce the overshooting of the system. Position control experiments for the SMA gripper are performed, and the experimental results demonstrate that a good position control performance of the gripper is obtained by using the proposed controller.

Strengthening the Foundations of an Administrative Building in Moscow

Characteristic features of the construction and design of a building, the section of its location, and basic causes of deformation are discussed. The procedure used to strengthen the upper part of the foundations by the installation of tension rods consisting of vertical angle brackets, longitudinal channels, turnbuckles, and anchors, as well as reinforced-concrete belts-walls with effective longitudinal reinforcement in the upper and lower sections, and distributing horizontal and vertical reinforcement and anchors is described.

Helical Collapse of a Whirling Elastic Rod Forced to Lie on a Cylinder

Helical Collapse of a Whirling Elastic Rod Forced to Lie on a Cylinder

406 国際熱核融合実験炉 (ITER) 用超伝導モデル・コイルの冷却・昇温時の機械的特性

The Engineering Design Activity (EDA) for the International Thermonuclear Experimental Reactor (ITER) was performed from 1992 under the collaboration of Japan, EU, Russia and the US. In the EDA, the Japan Atomic Energy Research Institute (JAERI) developed and tested the CS Model Coil under the international collaboration in order to develop fabrication technology of large superconducting coils and to demonstrate various properties. The CS Model Coil consists of the Outer Module and the Inner Module, which were pre-compressed by about 86 MN at room temperature with pre-compression structures composed of supporting beam and tension rod. Strain gages were attached to the tension rod to investigate the change of pre-compression force during cool-down, energizing, and warm-up. This paper describes the mechanical behavior of the CS Model Coil during cool-down and warm-up based on the measurement result of the tension rod strain.

Mechanical preloading of the Central Solenoid Model Coil

The inner and outer modules of the Central Solenoid Model Coil (CSMC) are mechanically compressed by a preload structure. The necessary preload is determined for the support of the modules' terminal leads. The forces in the preload structure are monitored by strain gauge bridges mounted to each of the structure's 16 inner and 16 outer tension rods during: (1) room temperature loading; (2) cool-down to the coil's operating temperature; and (3) electromagnetic operation. The preload structure is described and the variations in the preload with each stage of coil operation are presented. Analytical models are presented, which use the observed variations in preload to deduce equivalent mechanical properties for the coil modules.

高張力ロッドを用いたテンション構造のシステム化に関する研究

Although cables are most popular as material, steel rods are also used as tensile members in tension structures for long time in history. In this paper, required quality for the tension strings and their connections are discussed by defining tension structures as structural-system hierarchy composed of various levels of elements. Their required quality items are chosen through historical review including bridges and glass wall structures, and through their hierarchical studies using parabolic tension elements defined as sub-systems. Several type of connections for high-strength tension rods are proposed and selected for satisfying these requirements, followed by application for practical projects.

Numerical analysis of necking conditions in a thermoviscoplastic rod in tension

Necking conditions in a thermoviscoplastic rod in tension are studied with allowance for heat transfer within a broad range of strain rates and temperatures. The problem is solved in a long-wave approximation by the methods of linear perturbation analysis. The effect of the amplitude of the perturbations on the stability of plastic deformation is studied by means of nonlinear analysis. The calculations show that: (1) a neck is formed during tension of a solid rod for the values of the parameters realized in the experiment; (2) the critical strain during active tension depends appreciably on the wave number, particularly in the region of small wave numbers; 3) the critical strain does not depend significantly on the wave number at low strain rates.

Preloaded and Prestressed Reinforced Soil

A new construction method is described which aims at making reinforced soil structures, such as a geosynthetic-reinforced soil bridge abutment, very stiff and elastic. To make the deformation of a reinforced soil mass nearly elastic, a large preload is first applied by introducing tension into metallic tie rods which penetrate the reinforced soil and are connected to top and bottom reaction blocks. The tensile force in the tie rods functions as a prestress increasing the confining pressure and the stiffness of the soil is kept high. Compressive or tensile surcharge loads applied to the top block are supported by both the tie rods in tension and the soil mass in compression. Prestress is introduced in the reinforcement by preloading the tie rods, which contributes to maintaining the integrity of the soil mass. A working example and the result of a full-scale test are presented.

The in-vivo effects of an intramedullary implant evoking a constant radial stress to bone. An animal study in the tibia of the goat

Initial stability is essential for successful bone ingrowth into non-cemented prostheses. An entire new concept to increase the initial stability directly after implantation of intramedullary stems was developed (the tension rod prosthesis). The concept is based on a tension rod made out of memory metal that pulls a proximal stem of a prosthesis towards a distal anchor with a constant force. The stress generated along the long axis of the bone produces a radial stress around the prosthesis in the proximal femur. The main goal of this design is to increase the primary stability of the prosthesis during the ingrowth phase and to prevent stress shielding and bone resorption, as realized by the radial force applied to the proximal endosteum of the bone. To assess the efficacy of this concept and to collect data for the anchor design, an implant was developed for implantation into the tibia of the goat. Analyses of push-out strength and bone reactions were performed postoperatively. After 48 weeks the push-out strength of this implant was increased and the histological evaluation showed almost complete osseousintegration. Histomorphometrical analysis showed pronounced, permanent periosteal reactions, located around the anchor of the implant, which generates the radial stress. These first results showed that the bone can withstand the radial stress provoked by the anchor of the tension rod. It is concluded that the concept of a tension rod prosthesis is viable.

Desalination and industrial waste water treatment with the ROCHEM Disc Module DT

A new module system for membrane applications in desalination and purification of liquids is presented. The ROCHEM Disc Tube Modul Type DT can operate effectively and economically at increased turbidity and Silt Density Index levels for reverse osmosis and high pressure ultrafiltration. The disc-membrane stack of this module is assembled using hydraulic discs alternating with membrane cushions on a central tension rod with metal end flanges and is covered by a standard 8 inch pipe. This design allows for an easy alteration of module length and tube materials and facilitates inspection or changing of membranes in a quick and easy manner. The open feed channel between the hydraulic disc and the membrane surfaces ensures an unrestricted feedwater flow and consequently an optimal membrane cleaning from fouling deposits. The open channel ROCHEM RO DT module can operate without problems on sea water which has been pretreated only with normal mechanical filters such as a sand filter and a cartridge filter, usually making acid and antiscalant pretreatment unnecessary. Due to the low pretreatment requirements of the module, it can be used for industrial waste water applications. Design details of the DT module and results from practical field work in sea water desalination and - as example for industrial waste water treatment - in landfill leachate applications are discussed.

Evaluation of the influence of the scale factor on the fracture of rods

On the basis of the energy criterion of fracture a method of calculation of the relationship of the strength of quasibrittle rods in uniaxial tension and bending of rectangular and round cross section to their geometric dimensions was developed. With use of the analytical relationships obtained and known experimental data it is shown that with an increase in loading rate of the bodies being deformed the influence of the surface layer simulated by a physical surface on the strength of glass specimens first drops to a minimum value and then steadily increases.

On a variational problem from one-dimensional nonlinear elasticity

We study the regular calculus of the variations problem Minimize I μ(u) = ∝ −1 1 F(μu′(x), u(x)) dx on A μγ = { u ϵ W 1,1(−1, 1): u > 0 a.e., I μ ( u) < ∞, u(±1) = 1, and ∝ −1 1 u( x) dx = 2 γ}, for small values of μ. The function F( p, u) is convex in p but nonconvex in u. Using a phase-plane analysis we show that for small values of μ there is a unique minimizer of I μ , which takes approximately constant values apart from in two internal transition layers and in boundary layers at x= ±1. This result is suggested by a heuristic argument based on the structure of minimizers for the singular problem obtained by setting, formally, μ = 0 in the integrand of I μ . This problem arises from a one-dimensional elasticity theory for a cylindrical rod in uniaxial tension and with clamped ends.

Mine controls bad roof with trusses bolted on cycle : Barish, K Coal AgeV90, N5, May 1985, P62–66

Roof conditions deteriorated in a drift mine in Pennsylvania, and timber, steel, 10 ft roof bolts and resin bolts used in combination proved unsuccessful for roof control. A truss system of rods in tension was finally found satisfactory and was installed on-cycle using modified roof-bolting machines. An account is given of the application of the method.

Adhesion measurements of thin metal films on plastics

During tensile testing of partially metallized plastic tension rods, acoustic signals are generated. The source of the acoustic emission is located at the interface of the plastic with the metal film and can be related to the adhesion strength. The method can be used to compare qualitatively the adhesion strengths of thin metal films on various plastics.

Knee Joint Meniscal Degeneration as it Relates to Tissue Fiber Structure and Mechanical Resistance

Histological examination of knee joint meniscectomy specimens revealed previously undescribed basophilic spindle shaped structures. This study was done to explore their structure, to discuss potential mechanisms for their development and to establish diagnostic criteria. --4000 surgical specimens were examined. The intercellular substance of the cartilage was studied by means of mucopolysaccharide histochemical and polarisation optical methods. The three-dimensional fiber construction was examined stereometrically by means of a procedure derived from the universal stage method of the mineralogists. The spindle-shaped structures seem to be a sign of reduced mechanical tissue resistance. They are performed but become visible during meniscal degeneration. The mechanically efficient element of the menisci is a triple dimensional network of collagen fibers. Longitudinal fibers assure the tension resistance of the tissue. Transverse and diagonal fiber bundles tie the longitudinal fibers together. They act as tension rods. Therefore, compression resistance results. Meniscal degeneration mainly takes place in the tension rod fibers. Therefore, degenerated menisci tend to burst longitudinally. The condition of tension rod fibers in important as an indicator of mechanical resistance of the cartilage. It is a parameter for the assessment of meniscal damage.

Doubly curved shallow shells with rectangular base elastically supported by edge arched beams and tie-rods (I)

The equations of equilibrium of shallow shells with rectangular base elastically supported with edge arched beams are obtained through the variational principle together with corresponding boundary conditions and corner conditions. It is assumed that edge arched beams are of narrow plate form, so that only the rigidities in their own planes are taken into consideration, torsional rigidities and bending rigidities out of their own planes are neglected. In this paper, two kinds of corner conditions are discussed. First of these is pinned corner conditions. Second of these is simply supported corner conditions, such that the corner can be moved freely in horizontal directions. The former corresponds to the conditions of those with heavy tension beams, in which the tension rigidities of the rods can be assumed infinite. The latter corresponds to the conditions of elastically supported edge arched beams without tension rods. In the former case, the edge tangential displacement of shallow shells is assumed to be zero everywhere, so that the vertical displacement of the edge arched beams gives the only elastic supported forces. This kind of supporting conditions is a good approximation for practical roof design.

Stringed instrument construction

A stringed instrument, such as a guitar, with a neck and a body, is constructed to provide a stiffened neck adjustable to compensate for bending due to string forces and also to provide a sound, easily made connection, between the neck and the body. The neck is an assembly including a metallic stiffener embeded in a main neck part and carrying a tension rod. A nut on one end of the rod tensions the rod to control bending of the stiffener and of the remainder of the neck which is fixed to it. At its lower end the stiffener includes a rearwardly extending heel through which the neck is firmly connected to the body.