Only a few studies of the flow dynamics of stranded cables have been made despite their wide applications. This paper studies in detail the wake flow dynamics of two stranded cables using Particle Image Velocimetry at Reynolds number of 1,500. First and second order statistics were obtained for both cables. Besides, Proper Orthogonal Decomposition of the velocity and vorticity fields was used to determine the effect of the strands on the coherent structures. Results showed that wake flow dynamics are significantly affected by cable strands, specially as the ratio of cable overall diameter to strand diameter increases. Finally, this study provides detailed stranded cables wake flow dynamics. Such understanding could be used in optimizing cable design for different applications, to allow, for example, overhead transmission lines to passively increase their current carrying capacity.

This paper proposes reliability-based optimal design of a micro-grid system under service disruptions due to natural disasters. The objective is to determine the minimum number of generators and their distributions in the micro-grid so that the system’s recoverability (or resilience) and operation efficiency can be guaranteed under random failure scenarios of the power transmission lines. Power flow analysis combing with the Monte Carlo simulation (MCS) are used for uncertainty propagation analysis to quantify the system’s recoverability distribution and the transmission efficiency distribution under random failure scenarios of the transmission lines. The optimal allocation of the generators is much more reliable compared to the deterministic solutions without considering various uncertainties in the system. The proposed work is demonstrated through a 12-bus power system.

Poles are regularly placed along highways and are used to support signs, lights and electrical lines. The Midwest Guardrail System (MGS) is a standard W-beam guardrail system used throughout the United States to redirect vehicles that leave the roadway away from dangerous roadside obstacles, like ravines, water hazards, and bridge piers. Placing poles near a guardrail may affect its ability to safely contain and redirect vehicles. The compatibility of poles placed in the proximity of the MGS is studied using nonlinear finite element analysis. Computer simulations were conducted with vehicles impacting the MGS with varying lateral pole offsets between the back of the system and the front face of the pole, and varying longitudinal pole location from being placed directly behind a post to directly behind the unsupported rail half-way between posts. Results show that poles placed within 16 inches behind the MGS may cause concern in regard to acceptable crash test performance for guardrail systems. Additional simulations and full-scale crash testing is required before guidelines can be recommended.

In this paper, galloping vibrations of a lightly iced transmission line are investigated through a two-degree-of-freedom (2-DOF) nonlinear oscillator. The 2-DOF nonlinear oscillator is used to describe the transverse and torsional motions of the galloping cables. The analytical solutions of periodic motions of galloping cables are presented through generalized harmonic balanced method. The analytical solutions of periodic motions for the galloping cable are compared with the numerical solutions, and the corresponding stability and bifurcation of periodic motions are analyzed by the eigenvalues analysis. To demonstrate the accuracy of the analytical solutions of periodic motions, the harmonic amplitudes are presented. This investigation will help one better understand galloping mechanism of iced transmission lines.

According to the World Energy Council (WEC) the estimated energy of the wave power in the world is in the range of 8,000 to 80,000 TWh/year to depths of 100 meters or higher and actually the utilization of wave energy resource it is possible because it has been implemented in countries like Australia, Indonesia, Nigeria, United Kingdom, Norway, Portugal and Colombia evaluating different types of marine technologies that take the advantage of the kinetic energy in the ocean waves. Mexico according to the National Institute of Statistics and Information (INEGI) has a land area of 1,972,550 km 2 of which has a coastline of 11,150 km having potential for the use of their coasts. Baja California with a land area of 71,445 km 2 (3.6% of the country) is located on a peninsula in northwest Mexico and has 720 km of coastline on the Pacific Ocean (6.4% nationally) with a range of depths of 25.6 m to 650 m at a distance of the coastline of 15 km, which makes it suitable to evaluate the use of wave energy at local sites. With the completion of this work will contribute to the characterization of the sites that will present the best technical and economic conditions for its implementation, considering the physical characteristics of the site as well as connection points on the transmission lines operated by the Federal Electricity Commission (CFE). For the preparation of this study was carried out in three stages: a) Site Selection, b) Evaluation of Wave Energy and c) Economic evaluation of sites using RETScreen. Based on the characteristics of the coast of Baja California the results obtained are the following: 1) 18 sites were selected with a sea depth averaged of 50 m, the annual density power was 7.5 kW/m, this represents a potential of 210 MW considering an average length of 2 km in each site, 2) The economic evaluation of this type of project was for a period of 30 years in RETScreen, considers an annual inflation rate of 5% and obtains an investment cost of 9,538 US $/kW for this type of generation. We conclude that this source of energy will reduce dependence on fossil fuels and contribute to the generation of electricity in the state of Baja California diversifying the energetic matrix state by the use of clean and renewable sources, which represents an investment opportunity between the public and private sector.

Shunt capacitor banks are used on power distribution feeders to reduce losses and regulate the voltage level. The decrease in transmission line current also leads to an increase in the amount of demand that can be supplied without increasing the size of the conductors. In order to maximize the benefit of adding capacitor banks to the distribution feeders, the optimal size and location of the capacitors must be determined. This paper presents a novel optimal control approach to both regulate the voltage drop and reduce the copper loss. A cost function that penalizes both energy losses and voltage drop is developed. The optimal size and location of capacitors can be found using the optimal control solution. Computer simulation results are compared with existing methods of determining the optimal size and location of capacitors. Our approach improves on current methods by providing flexibility to both regulate voltage levels and reduce losses.

Recently, the environmental impact of wind farms has been receiving increasing attention. As land is more extensively exploited for onshore wind farms, they are more likely to be in proximity with human dwellings, infrastructure (e.g. roads, transmission lines) and environmental features (e.g. rivers, lakes, forests). As a result of regulatory constraints, this proximity causes significant portions of the wind farm terrain to become unusable for turbine placement. In this work, we present a constrained, continuous-variable model for layout optimization that takes noise and energy as objective functions, based on Jensen’s wake model and ISO-9613-2 noise calculations. A multi-objective genetic algorithm (NSGA-II) is used to solve the optimization problem, considering a set of land use constraints, which are handled with static and dynamic penalty functions. A set of test cases with different number of turbines and percentages of land availability are solved. Results from this bi-objective optimization model illustrate how the severity of the land use constraints affects the trade-off between energy generation and noise production.

The field of control and stabilization of distributed parameter systems described by partial differential equations has recently seen an increasing number of results published by very respected researchers in excellent control engineering and applied mathematics journals. This paper presents a survey of control and stabilization results with emphasis on controls. Various distributed parameter dynamic control and stabilization problems have been studied corresponding to heat conduction, wave propagation, Schrodinger equation, crowd (swarm) dynamics, magneto-hydro-dynamic channel flow, string and beam equations, viscous Burger equation, and general diffusion equations. Various techniques have been used for control and stabilization of such systems: Lyapunov stabilization, backstepping, gain scheduling, singular perturbations, sliding mode control, observer driven controller, tracking control, sampled-data control, neural networks. The field still remains widely open for future research. Applications of surveyed results to various areas including robots, aircraft, networks, transmission lines, electrochemical processes in energy systems are indicated.

Catastrophic cascading system failures such as the August 13th Blackout of 2003 highlight the vulnerability of the North American power grid, and emphasize the need for research to mitigate failure events. The incorporation of robust design, the insensitivity of system performance in the presence of noise (or uncertainty) from both internal and external sources, into existing and future power grid design strategies can increase system reliability. This paper presents a high-level topological network approach to power grid robust optimization as a solution for designing against cascading system failure. A mathematical model was created representing a standard power grid network consisting of generation and demand nodes, as well as node connections based on actual topological transmission line relationships. Each node possesses unique power generation or demand attributes, and various network connection configurations are examined based on system demand requirements. In this model, failure events are initiated by the removal of a single network connection, and remaining loads are redistributed throughout the system. Cascading failure effects are captured when the existing network configuration cannot support the resulting demand load, and transmission line failures continue propagate until the system again reaches a steady state, based on remaining nodes and connections. The primary goal of this research is to facilitate an understanding of design trade-offs between system robustness and performance objectives. In this research, robustness is defined as the resilience to initiating faults, where a robust network has the ability to meet system generation requirements despite propagating network failures. Primary performance objectives are total system cost and the ability to satisfy network demand after a failure, while robustness is represented as the lack of variability in the amount of demand which is satisfied after a failure. By understanding network reactions due to cascading failures, as well as performance trade-offs required to mitigate these failures, reliability in power grid systems can be increased.

Turbo generator shafts are manufactured through the extrusion process. This results in formation of weak planes along the extrusion direction. Under service loading (e.g. cyclic torsion due to electrical line faults), large longitudinal cracks often form in these shafts before the appearance of any circumferential cracks. The presence of these cracks could severely compromise the shaft resonance frequencies. Here, we investigated the dynamic response of solid turbo generator shafts with longitudinal and circumferential cracks. The longitudinal cracked section of the shaft section was modeled as a shaft with reduced effective torsional rigidity. The effective torsional rigidity was found to be a function of ratio of crack depth to the shaft radius only. The circumferential cracked section was modeled as a torsional spring, with the torsional spring constant determined using fracture mechanics principles. It was found that the resonance frequency of the shaft may be little affected by the presence of a longitudinal crack. The resonance frequencies of the shaft with the circumferential crack depend on the crack length and its location. The effects of crack surface interactions for both longitudinal and circumferential cracks were also investigated. For circumferential cracked shafts, the sever crack surface interaction results in the peak response frequency approaches to that of un-cracked shafts. However the frequency where the peak response occurs for a longitudinally-cracked shaft generally exceeds that of un-cracked shaft first resonance frequency.

The design of hydraulic transmission lines for control and actuation requires accurate knowledge of their dynamic response: some standard techniques are known to obtain a consistent dynamic model of a fluid line, including the contribution of inertia, compressibility and friction. In this paper an efficient procedure is developed for simulating the dynamic response in both the frequency and time domains, focusing the attention on the modal analysis of a discretized model of a fluid line. A bi-dimensional approach is adopted, modeling the laminar flow frequency-dependent friction by means of non-integer order differential laws, which may improve the accuracy of the simulated responses in comparison with more traditional Newtonian models.

The Split Ring Resonator (SRR) has been developed and explored for a number of sensing technologies and devices. A SRR can be equivalently regarded as an LC circuit; changes in the dielectric environment will change the equivalent capacitance of the resonator, resulting in a shift of the resonant frequency as well as the quality factor (Q-factor).This makes the device a promising application for continuous personal health monitoring throughout the day. In this work, we are developing a passive radio frequency sensor based on ring resonator designs. The targeted frequency band is within 2.4–2.5GHz ISM (Industrial-Scientific-Medical radio band) and is available for medical devices. The resonator structure is first simulated using Finite Difference Time Domain (FDTD) method by CST Microwave Studio to determine the resonant frequency. Then for the experimental study, a microstrip transmission line with a double split ring resonator (DSRR) was fabricated on a printed circuit board (PCB) with biocompatible PVC coating on top. Tuning the thickness and material of the biocompatible coating can further improve the biocompatibility, Q-factor, and resulting sensitivity (mS) of the device. Reflection spectrum (S11) is measured using a network analyzer at 100 mW. The current design senses changes in conductivity down to 0.5 mS. By reducing coating thickness, reducing the spacing between resonators, and with more efficient resonator designs we expect to further improve this sensitivity. This sensor could be utilized by either implanted into the interstitial layer beneath the skin or embedded into a contact lens to sense tear salinity levels.

In the present study, a simplified and efficient numerical simulation approach has been developed for thermal analysis for the high voltage (HV) cable tunnel with extended length. The thermal behavior analysis of different HV cable arrangements, thermal properties, as well as the amount of heat dissipating towards the water-cooled system and the surroundings was analyzed and discussed in detail. With a typical sand-filled HV cable and pipe work arrangement, the circuit water-cooling system would take up around 85% of the total heat dissipation. The remaining heat is catered by the tunnel ventilation system and the soil surrounding the tunnel. Note that an air-filled cable trough is less preferable.

Due to material discontinuity and inherited forming mechanism, the conductor-connector system of a crimped-type splice connector is highly sensitive to aging of system components, especially during high-temperature operations. Furthermore, due to the increase in power demand and limited investment in new infrastructure, existing overhead power transmission lines often need to operate at temperatures higher than the original designed values. This has led to the accelerated aging and degradation of conductor-connector systems. The implications of connector aging are two-fold: (1) significant increase in electric resistivity of the splice connector and (2) significant reduction in the connector clamping strength. Therefore, splice connectors are one of the weakest links in the electric power transmission infrastructure. The integrity of crimped-type splice connectors is one major concern in the efficiency and reliability of power transmission system. In this paper we present results from high temperature integrity studies of two-stage splice connector systems used for both ACSR and ACSS transmission conductors. The forming process and thermal cycling degradation behaviour are simulated using finite element modeling, which shows good agreement with degradation trends obtained from experimental data. A numerical simulation protocol has been developed to provide guidance in predicting the effective lifetime of ACSR and ACSS splice connector systems.

The quality and reliability of interconnects in microelectronics is a major challenge considering the increasing level of integration and high current densities. This work studied the problem of transient Joule heating in interconnects in a two-dimensional (2D) inhomogeneous model. The transmission line matrix (TLM) method was implemented with link-resistor (LR) and link-line (LL) formulations, and the results were compared with a finite element (FE) model that was developed in LSDyna. This comparison showed that the overall behavior of the TLM models were in good agreement with the FE model while, near the heat source, the transient TLM solutions developed slower than the FE solution. The steady-state results of the two models were identical. The two TLM formulations yielded slightly different transient results, with the LL result growing slower particularly at the source boundary and becoming unstable at short time-steps. It was concluded that the LR formulation is more accurate for transient thermal analysis. Computational efficiency of the TLM method and its ability to accept non-uniform 2D and 3D mesh and variable time-step makes it a good candidate for multi-scale analysis of Joule heating in the interconnects.

In this paper, a multi-layer LCP substrate fabrication process was described and millimeter wave transmission lines and filters were designed and fabricated on the LCP substrate. Various transitions from a CPW to a microstrip line with their characteristic impedance being 50 ohms were investigated. The characteristics of the wirebonding assembly for connecting two transmission lines was also examined. The measurement results show that an insertion loss of 1.3 dB at 60 GHz can be achieved for the two-wire bonding trasmisssion line including two transitions from a CPW to a microstrip line.

We proposed an approach to construct a 2D Fresnel lenses by acoustic network. This lens is composed of an array of Helmholtz resonators. The resonance at individual resonators results in effective focusing even the plate has subwavelength thickness. The FEM simulation results presented the ultrasonic wave propagation through the lenses together with the resulting diffraction pattern.

An advanced patented process [1] for generating power from waste heat sources can be put to use in Industrial operations where much of the heat is wasted and going up the stack. This waste heat can be efficiently recovered to generate electrical power. Benefits include: use of waste industrial process heat as a fuel source that, in most cases, has represented nothing more than wasted thermal pollution for decades, stable and predictable generation capability on a 24 × 7 basis. This means that as an efficiency improvement resource, unlike wind and solar, the facility continues to generate clean reliable power. One of the many advantages of generating power from waste heat is the advantage for distributed generation; by producing power closer to its ultimate use, it thereby reduces transmission line congestion and losses, in addition, distributed generation eliminates the 4% to 8% power losses due to transmission and distribution associated with central generation. Beneficial applications of heat recovery power generation can be found in numerous industries (e.g. steel, glass, cement, lime, pulp and paper, refining, electric utilities and petrochemicals), Power Generation (CHP, MSW, biomass, biofuel, traditional fuels, Gasifiers, diesel engines) and Natural Gas (pipeline compression stations, processing plants). This presentation will cover the WOW Energy technology Organic Rankine Cascading Closed Loop Cycle — CCLC, as well as provide case studies in power generation using Internal Combustion engines and Gas Turbines on pipelines, where 20% to 40% respectively additional electricity power is recovered. This is achieved without using additional fuel, and therefore improving the fuel use efficiency and resulting lower carbon footprint. The economic analysis and capital recovery payback period based on varying Utility rates will be explained as well as the potential Tax credits, Emission credits and other incentives that are often available. Further developments and Pilot plant results on fossil fired plant flue gas emissions reductions will be reported to illustrate the full potential of the WOW Energy CCLC system focusing on increasing efficiency and reducing emissions.

There has been a lot of research in the development of a hybrid hydraulic actuator driven by various smart materials. The basic operation of these actuators involves high frequency bidirectional operation of the active material which is converted to unidirectional motion by a set of valves. The response of the actuator also shows resonant peaks similar to that of SDOF mechanical systems and indicates a region of maximum output. At these high driving frequencies, the inertial effects of the fluid mass dominate over the viscous effects and the problem becomes unsteady in nature. Geometrical parameters of the flow path are also important. Due to the high pressures existing inside the actuator and the presence of entrained air, compressibility of the hydraulic oil also has to be taken into account. Hybrid actuators using the magnetostrictive material Terfenol-D and the electrostrictive material PMN have been developed in our laboratory, with hydraulic oil as the working fluid. Several key design parameters, which include output cylinder size, diaphragm thickness, reed valve thickness and tubing diameter, along with operational conditions, like input current and bias pressure within the fluid, have been varied to identify a set of optimum driving conditions. Tests at no-load and with load have been carried out for unidirectional motion of the output piston. To characterize the input driving circuitry and magnetic flux path, we have also carried out dynamic tests with the Terfenol-D rod and analyzed its magnetic circuit (flux density vs. frequency) response. In this paper, we develop a mathematical model of the hydraulic hybrid actuator to show the basic operational principle under no-load and loaded conditions and to describe the resonance phenomenon affecting the system performance. The dynamics of the input driving circuit have been included in the model. The fluid passages have been represented using the transmission line model, giving rise to strongly coupled ordinary differential equations which are solved using a lumped parameter approach. This model is then used to calculate the no-load velocity of the actuator and also its blocked force. Finally, we use the model to find optimal pumping frequency to get highest performance with different active materials and also to predict the pump sizing for desired output velocity and load lifting capability.

We report the numerical design and preliminary experiment of 2-D acoustic metamaterials composed of a planar network of subwavelength Helmholtz resonators. The considerably smaller size of the Helmholtz resonator to the corresponding resonant wavelength, allows a compact and light weight design for kilohertz frequency applications. Based on transmission line model to describe the acoustic wave propagation inside such ultrasonic metamaterials, we derived the acoustic parameters such as effective density and compressibility. Extremely large or even negative value of effective density and compressibility can be designed in this acoustic metamaterial. Our simulation demonstrates the focusing and imaging of sound sources through different lenses made of this novel acoustic metamaterial, which may have great potential application in ultrasound imaging. The influences of frequency and source position on the property of the focused image are also investigated.