eLearning

Comments on "Unresolved paradox in circuit theory"

R. Van Malderen Proceedings of the IEEE, 1967

A noise source connected to a universal dc motor would violate the second law of thermodynamics with commonly accepted models of lumped circuit elements. It is shown that this paradox is due to a too idealized representation of the motor model.

Concept validation of an automatic passenger counting system for trams

R. Kovacs; L. Nadai; G. Horvath 2009 5th International Symposium on Applied Computational Intelligence and Informatics, 2009

The system shown addresses the problem of automatic passenger counting (APC) in trams with high utilization, uncoordinated boarding and lacking air suspension. Conventional APC systems do not provide sufficient accuracy under these conditions. A concept for determining the total weight of the vehicle using only data already acquired on the vehicle or available from other sources has been worked out. ...

Study on Control Strategy of Integrated Hydraulic Propulsion Ship

Ji Yulong; Sun Yuqing; Chen Haiquan; Chen Lei; Zhang Yindong; Zhang Hongpeng 2007 International Conference on Mechatronics and Automation, 2007

A control strategy, constant power and variable power combination control (CVCC), was put forward for integrated hydraulic propulsion (IHP) ship against its characteristics. Theoretical analysis was conducted through working condition matching characteristic charts to evaluate the effect of this control strategy. Modeling and simulation of IHP ship was researched, and the theoretical analysis results were proved by the simulation results. ...

Fall Prediction of legged robots based on energy state and its implication of balance augmentation: A study on the humanoid

Zhibin Li; Chengxu Zhou; Juan Castano; Xin Wang; Francesca Negrello; Nikos G. Tsagarakis; Darwin G. Caldwell 2015 IEEE International Conference on Robotics and Automation (ICRA), 2015

In this paper, we propose an Energy based Fall Prediction (EFP) which observes the real-time balance status of a humanoid robot during standing. The EFP provides an analytic and quantitative measure of the level of balance. Both simulation and experimental studies were conducted and compared with the previously proposed indicators, such as Capture Point (CP) and Foot Rotation Indicator (FRI). ...

Sliding contact energy measurement using calibrated acoustic emission transducer

B. Bhushan; Y. Wu; N. S. Tambe Digest of the Asia-Pacific Magnetic Recording Conference, 2002

Acoustic emission (AE) transducers are commonly used to monitor the intensity of head-disk contact. However, analytical methods used to obtain electrical energy of the AE output signal and mechanical energy dissipated in typical head-disk contacts are still, to a large extent, not well understood. In the present study we introduce a method to obtain the electrical energy of the AE ...

IEEE-USA E-Books

• Mechanical Energy Harvesting with Piezoelectric Nanostructures: Great Expectations for Autonomous Systems

  This chapter contains sections titled: Introduction Mechanical Energy Harvesting using MEMS Mechanical Energy Harvesting using Piezoelectric Nanostructures Further Improvements at the Nanoscale Towards Completely Autonomous Systems: Multisource Approach Conclusions and Future Prospects

• Motors

  This chapter discusses the basic design and construction of motors and reviews some of the safety requirements when dealing with motor circuits and their associated loads. Electric motors convert electrical energy to mechanical energy to perform work. Motors are a very important element in the operation of the auxiliary systems that support power plant operations. For example, in nuclear power plants that are of a pressurized water reactor (PWR) design, the primary coolant is circulated between the reactor vessel and the steam generator by a reactor cooling pump (RCP). This is a critical function performed by electric motors. The National Electrical Safety Code (NESC) requires some minimum safety precautions when dealing with motor circuits and the loads connected to the motors. The induction motor is constructed with a stationary winding (the armature) that is installed in slots of a stationary core (stator).

• Introduction to Electromagnetic Transient Analysis of Power Systems

  The analysis and simulation of electromagnetic transients has become a fundamental methodology for understanding the performance of power systems, determining power component ratings, explaining equipment failures or testing protection devices. Power system transients can be electromagnetic, when it is necessary to analyse the interaction between the (electric) energy stored in capacitors and the (magnetic) energy stored in inductors, or electromechanical, when the analysis involves the interaction between the electric energy stored in circuit elements and the mechanical energy stored in rotating machines. This book provides a basic background to the main solution techniques presently applied to the calculation of electromagnetic transients, and gives details of the main applications of the most popular transient tools (insulation coordination, power electronics applications, protection). It discusses new developments (e.g. dynamic average models, interfacing techniques) mostly aimed at overcoming some limitations of the present software tools.

• Solar and Wind Energy

  Wind is the natural movement of the air due to differences in atmospheric temperatures and pressures. The wind turbine converts the kinetic energy of the wind into mechanical energy at the shaft of the turbine. The shaft of the turbine in turn is connected to a generator where this mechanical energy is converter to electrical energy. For utility operations, the generator is required to operate at a substantially faster speed than the shaft of the rotor connected to the wind blade. The power curves for various types of wind turbines are different, depending on the design of the machine. For very low wind speeds below the minimum operational speed of the machine, the wind turbine is not able to convert an adequate amount of energy to drive the generator. Concentrating solar power (CSP) systems receive solar energy and concentrate this energy into a collector.

• Hydraulic Turbines

  Hydraulic turbines convert the potential energy contained in a head of water to mechanical energy in the rotor of the turbine. The amount of power transferred is proportional to the amount of head across the turbine blades and the flow through the turbine blades. Therefore, in the application of hydraulic turbines, control of the flow of water through the turbine will control the amount of mechanical power developed by the turbine shaft which will, in turn control the amount of electrical power delivered by the hydraulic turbine generator. Fundamentally, flow control is achieved by the use of either wicket gates that control the flow to the turbine blades and/or by the use of variable pitch blades on the turbine rotor. This chapter discusses the three basic types of hydro???turbine plants: impoundment, diversion, and pumped storage. It also describes the three basic types of hydro???turbine unit blade designs: reaction, impulse, and kinetic energy units.

• Magnetic Actuators Operated by DC

  Magnetic actuators use magnetic fields to transform electrical energy into mechanical energy. Thus they are a type of transducer. This chapter discusses in detail the most common types of magnetic actuators operated by direct current (DC). The magnetic actuators discussed in the chapter are: solenoid actuators, voice coil actuators, other linear actuators using coils and permanent magnets, proportional actuators, rotary actuators, magnetic bearings and couplings, and magnetic separators.

• Steam Turbines

  This chapter discusses the basic design and components of a high pressure, intermediate pressure, and low pressure steam turbine. Turbines provide the primary means of converting the thermal energy contained in the steam system to the mechanical energy in the turbine shaft. This is used to drive the main generator in a power plant as well as various auxiliary pieces of equipment such as boiler feed pumps. The amount of energy exchanged between the steam system and the turbine system during this thermal to mechanical energy conversion process is a function of both the velocity of the steam flow as well as the differential pressure drop across the steam blades. Superheated steam from the boiler or steam generator enters the high pressure (HP) section of the turbine where the steam is expanded across the high pressure turbine blades. The chapter also describes the safety hazards associated with turbine system equipment.

• Controlling Civil Infrastructures

  Controls is well-established in most of the major engineering disciplines- electrical, chemical, mechanical, aerospace. Historically, an important exception has been civil engineering, and, as this chapter illustrates, recent developments are bridging the gap. The importance of understanding the dynamics of civil structures has been recognized since the 1940 Tacoma Narrows bridge collapse, but feedback control of buildings, bridges, towers, and other structures is a relatively recent development. The concept of active control for such systems was first introduced in 1972. Since then, a vast literature has been generated on the topic, and, more impressively, a number of successful implementations have been completed (the first full-scale one in 1989). Many of the largest applications have been to buildings in Japan, driven by the desire to achieve protection against earthquakes. The first implementation of structural control was based on active mass dampers (AMDs). An AMD system couples an auxiliary mass to the structure through an actuator. Sensor measurements of building movement and stresses are used in a control algorithm to move the auxiliary mass relative to the building. Such systems are versatile and capable, but issues of reliability and power consumption have driven the search for improvements. The next significant development was controllers that employed a combination of active and passive devices. These hybrid active/passive control systems (no relationship to the hybrid discrete/continuous systems discussed in Chapter 7) rely on one of two approaches: hybrid mass damping and hybrid base isolation. The former is especially popular. The largest building in Japan, the Yokohama Landmark Tower, incorporates two hybrid mass dampers (HMDs), each weighing 170 tons. The most recent innovation is the semiactive control device. These devices cannot i nject mechanical energy into the structure but have properties that can be manipulated to achieve structural disturbance rejection. In many cases, they can operate on battery power; this is a significant advantage since seismic events can interrupt main power supplies. Examples of semiactive devices include variable-orifice fluid dampers, variable-stiffness devices, variable-friction devices, controllable and tuned liquid dampers, and magnetorheological dampers. The last topic is discussed at some length in this chapter, and experimental results are shown.

• Transformations of Electrical and Mechanical Energy

  This chapter contains sections titled: Sources and Recommended Reading

• Basic Thermal Cycles

  This chapter discusses the basic Brayton and Rankine thermodynamic process. It utilizes the American Society of Mechanical Engineers (ASME) steam tables which list properties of water and steam in United States customary units; so the discussion of thermodynamics utilizes United States customary units. Most methods of energy conversion involve the conversion of one form of energy to thermal energy, and generation stations use water and steam as a media to transmit this thermal energy from one part of the system to another where it is then converted to mechanical energy. This mechanical energy is used to drive a generator which converts the mechanical energy to electrical energy. Since water and steam are one of the most common methods used for the thermal part of this energy conversion process, a review of steam fundamentals and basic thermodynamic laws along with the typical types of equipment used in this process is essential.