Tower Section Research Articles

DOOR OPENING ANALYSIS OF WIND TURBINE STEEL TUBULAR TOWER

The main objective is to investigate the stresses around the door opening for the load cases that creates highest stresses. The influence of different material thicknesses at the tower lower parts. It investigates the lower tower section which includes the door opening which is used for service and maintenance inside the tower. The loading of the tower generates the stresses around the door opening and these stresses will analyze for static analysis using the FEM software ANSYS 14.5. As there is more probability of having crack near the door opening. To investigate the influence on the stress level and ultimate load of the tower, the tower shell thickness around the door opening varied in simulation .There are total six models prepared in the paper among which two models are prepared with uniform thickness of 38 mm, two models are prepared with 38 mm thickness at the base and 15 mm at the top and two models are prepared with 70 mm thickness at the base and 15 mm at the top. For every condition there are two wind cases considered in first direction of wind is considered on the side of door opening and in second case wind direction is considered on the opposite side of the door opening. After got the values for the stresses fracture analysis and fatigue analysis of the section near the door opening have carried out. We uses steel of grade 355 (S355) and wind data has calculated according to the IS 875 part 3.

Control of a Flywheel Energy Storage System for Power Smoothing in Wind Power Plants

This paper deals with the design and the experimental validation in scale-lab test benches of an energy management algorithm based on feedback control techniques for a flywheel energy storage device. The aim of the flywheel is to smooth the net power injected to the grid by a wind turbine or by a wind power plant. In particular, the objective is to compensate the power disturbances produced by the cycling torque disturbances of the wind turbines due to the airflow deviation through its tower section. This paper describes the control design, its tuning, as well as the description of the experimental setup, and the methods for the experimental validation of the proposed concepts. Results show that the fast wind power fluctuations can be mostly compensated through the flywheel support.

Analysis and Control of Cable-Stayed Bridges Subject to Seismic Action

Cable-stayed bridges are key points in transport networks and at present one of the most challenging structures for the civil engineering community. The integrity of these bridges should be guaranteed even under extremely large earthquakes. This paper begins with a discussion of the advantages of a new non-linear static “Pushover” procedure that includes the three-dimensional contribution of the governing vibration modes. The efficacy and the accuracy of the proposed Pushover in the non-linear seismic analysis of bridges with significant coupling between the towers, deck and cable system is verified. In the second part of this paper, the seismic responses of several cable-stayed bridges have been studied, verifying the influence of the tower shape, cable arrangement and the main span length on the structural behaviour under strong ground motions. Severe damage is identified at critical tower sections by means of extensive non-linear dynamic analyses. Finally, retrofit solutions with viscous dampers (VDs) and yielding metallic dampers (MDs) connecting the deck and the tower in the transverse direction are explored. The proposed connection with dampers effectively prevents yielding of the reinforcement and cracking in the tower legs.

Relation Among Velocity of Lightning Travelling Wave, Lightning Stroke Current, and Tower Footing Resistance to Study Back-Flashover on the Insulators in Transmission Tower

This paper studies the impact of back-flashover on the insulators with various velocities of lightning travelling wave, the lightning stroke current, and the tower footing resistance. The impedance of transmission tower section such as top tower, upper phase, middle phase, and lower phase that is calculated with lightning velocity dependent parameters is also considered. The velocity of lightning travelling wave at 300 m/μs and 200 m/μs is compared to consider back-flashover including maximum voltage at the cross arm and voltage across insulators. The results is shown that the velocity of lightning travelling wave plays an important role for the back-flashover voltage across insulator as well as the tower footing resistance and the lightning stroke current.

Negotiating Identity While Scaling the Walls of the Ivory Tower

Within these pages I engaged in critical autoethnographic storytelling, referred to as cuentos, to highlight the reflexive processes impacting my identity negotiation while in graduate school (an “Appendix” further explicating this critical autoethnographic approach is also provided). As will be seen, the reflexivity necessary to explore the impact my past had on my interactions while a graduate student stemmed from understanding borderland theorizing (Anzaldúa, 1987). Through cuentos about my Mago, Margaret Ruth, Margo, and Margarita Refugia identity constructions, I painfully expose lived experiences representing surreal, emotional, often devastating, unshakable, and unbelievable lived realities. In contrast to the cuentos sections of this article, the scaling the walls of the Ivory Tower sections are presented in a less emotional, more intellectual state of mind reflecting borderland theorizing about (post)colonial wounds and assimilationist socialization processes that eventually lead to my emerging conciencia de la Mestizo—processes that bring to light academic and socialization challenges I faced while attending graduate school as a racial/ethnic minority woman and single mother of lower socioeconomic background.

Treatment and reuse of wastes of a vegetable oil refinery

An industry manufacturing refined vegetable oil and hydrogenated vegetable oil (vanaspati) with a capacity of 58.5 tonnes/day generated wastewaters and solid wastes (viz. spent earth, spent catalyst, chemical and biological sludges). The wastewater streams were mainly from vat house after soap splitting, floor washing, cooling tower, boiler and filter press. The chemical composition of the wastewater from cooling tower and boiler sections and solid wastes indicated that these wastes could be recycled and reused in the process after preliminary treatment. The combined wastewater from other streams was being treated in the existing effluent treatment plant (ETP) and the treated effluent was not conforming to the limits prescribed for discharge into inland surface water as stipulated by Central Pollution Control Board, Ministry of Environment and Forests, Government of India. After adoption of some of the suggested measures, the treatment efficiency of the existing ETP improved and treated effluent conformed to the prescribed limits for discharge into inland surface water. The recycle, recovery and reuse of the wastes were adopted in the industry in order to achieve zero discharge for economical and ecological gains.

Reradiation (echo) analysis of a tapered tower section supporting a side-mounted DTV broadcast antenna and the corresponding azimuth pattern

Reradiation from a non-vertical obstruction such as a tapered section of a broadcast antenna supporting tower is analyzed. The reradiation takes on the form of a cone, which is symmetrical about the tower leg axis, modified by the reflection coefficient that varies with azimuth. The reradiation is directed either above the horizon where it is lost or below the horizon where it interferes as an echo with the direct radiation. The reradiation has an elevation pattern which is a replica of the transmitting antenna elevation pattern, but is redirected by the nonvertical tower leg. The reradiation combines with the direct radiation to form an azimuth pattern which varies with distance from the broadcast antenna. The reradiation, being an echo, is analyzed for multipath distortion of the VSB pulse. It is shown that the impact on DTV receiver threshold is minimal.

Modeling the nonlinear seismic behavior of cable-stayed bridges with passive control bearings

A three-dimensional nonlinear finite element model is developed for cable-stayed bridges under static and dynamic loadings based on the total Lagrangian formulation. The model can account for the large displacements that are usually associated with extended in plane contemporary cable-supported structures. A four-node isoparametric cable element is introduced and proposed for the idealization of cables. The element can predict both in-plane and out-of-plane responses. In addition, the cable element takes into consideration the effect of pretension which is one of the features of cable-stayed bridges. Four-node isoparametric beam elements are proposed to model the deck and towers. The element is formulated for general symmetric sections including multi-vent box sections, plate sections and cut-off corner tower sections. The introduced beam element handles large displacements, shear deformations and curved configurations. However, the main advantage of the proposed element is the reduction of degrees of freedom associated with some deck types such as the box sections where one beam element can represent the main girder. Moreover, the internal nodes for both beam and cable elements can be eliminated during the solution of equilibrium equations; however the response can be retrieved at their locations without approximations or loss of accuracy. Furthermore, the eccentric nature of cable-deck and cable-tower connections can be considered by a proper transformation. The control and improvement of the vibrations of cable-stayed bridges necessitates the inclusion of energy dissipation devices at certain locations. The problem becomes difficult to solve with the very large number of degrees of freedom associated with accurate modeling of the bearings and the bridge components. A simplified model is proposed for the dissipation devices in which a two-node element is introduced for a stiffness-type analysis approach. The element is capable of withstanding axial and shear forces. The parameters that control the hysteretic behavior of the element can be estimated out of sophisticated analytical models and/or experimental results. In addition, guidelines based on simplified assumptions are presented for approximating the force-displacement curve of some devices for preliminary analysis and design. The investigation of an appropriate passive control system started with exploring the ideology of seismic isolation by considering a two-dimensional model for a single-plane harp-type cable-stayed bridge. In order to have more realistic insight into the usefulness of passive energy dissipation devices, two different cable-stayed bridges models with double-plane harp and fan-type cables are presented for the numerical analysis. Significant reduction in earthquake induced forces along the bridge can be achieved with the energy dissipation devices as compared to the case of using conventional connections.

The electrostatic transformer

The electrostatic transformer (EST) has been developed to match the large-capacitance hadronic signal towers of liquid ionization calorimeters to relatively low-capacitance, low-noise preamplifiers. The intrinsically fast internal impedance transformation by the EST preserves the fast rise time required for effective calorimetry in the high-rate environment of the SSC/LHC. Another advantage of the EST over an external ferrite-core transformer (FTC) is that the former is unaffected by the large magnetic field required in most detector configurations. The performance of the EST is limited primarily by crosstalk to neighboring towers, which delocalizes the signal and degrades the signal to noise ratio. In practical applications both these effects can be made small. To aid in the evaluation and design of useful ESTs we have studied an aluminum model of a hadronic tower section of typical dimensions. The measurements on the model agree well with calculations using a simple electrical model.

Water Quality Considerations in Malaysia's First Waterflood

Malaysia's first waterflood, a seawater injection system, was placed in service in the Tapis field in 1982. This paper outlines the design basis and describes the system. Then water quality during and after startup and the formulation of a water quality guide using Millipore membrane filtration tests are discussed. The experience gained and data presented can be applied to current and future waterfloods.

The TV Helical Antenna Adapted to Structural Tower Shapes

The side-fire helical antenna, successfully used for UHF and VHF high channel television transmission, has now been adapted for low channel VHF service. Investigation of properties of a helical radiator wound around a polygonal supporting structure has made possible the required increased bandwidth and provided directional patterns for special TV coverage applications. Through scale model work, a channel 2 directional antenna has been developed for installation around a triangular tower section.