Current Flow Controller Research Articles

An Enhanced Operational Stability of Organic Light Emitting Devices with Polymeric Buffer Layer

A uniform and robust polymer-based hole injection layer (HIL) was formed by spin-casting process in an ambient air condition. The rough surface of indium tin oxide (ITO) was covered by this polymer-based HIL which plays an important role as a buffer layer. The utilization of this buffered HIL polymer resulted in an enhanced long-term stability of organic light emitting devices (OLEDs). In addition, we found that the precise control of hole current flow is possible by doping of 9,10-dicyanoanthracene (DCA) with moderate electron affinity (∼3.5 eV) plausibly due to a strong dipole interaction with the polymeric HIL material. As a result, a new buffer layer doped with DCA showed a substantially controlled hole injection into an emitting layer (EML) which causes a much more enhanced lifetime of the blue OLED by a factor of 4.3.

Bose-Einstein Condensate-Hidden Riches for New Forms of Technology and Energy Generation; Potential for Glimpse into Inner Reality

Abstract With the announcement of t he recent successful production of a Bose-Einstein condensate (BEC) of photons, a circle has been completed which started in 1925 with the vision of Albert Einstein and Satyendra Nath Bose – a sustained macroscopic condensed state of matter where all atoms are in the same lowest quantum state. The creation of an all-optical BEC, involving a surprisingly straightforward “tabletop” method which bypasses the normally requisite laser/evaporative cooling equipment and ultra-high vacuum chambers necessary for production of the standard delicate atomic BEC, elevates this phenomenon to a new level well beyond its current perception as mere laboratory curiosity. Accordingly, this development certainly heralds eventual incorporation of atomic and photon BECs as standard operating components of energy-efficient mechanical, optical and electrical systems, implying novel ingenious engineering protocols amenable to all the tools of non-linear and quantum optics. Pointing towards such a promising technological future are the suggestion that a photon BEC could serve as a new high-energy ultra-violet (UV) laser photon source, as well as the recent unprecedented implementation of a closed-loop atom circuit (toroidal atomic BEC) demonstrating precise control of superfluid current flow, forecasting the coveted development of an atomic SQUID. Perhaps more significantly, the new highly robust and manageable optical BEC will allow heretofore unfathomable precise probing of the atomic and nano-levels of nature, affording novel high-quality testing procedures of the major foundations of quantum mechanics itself. Such a primary advancement, providing a clearer glimpse into the microscopic realms, may present us as never before with an unprecedented view of the quantum engine that underpins physical reality itself and help place the contextual nature of entanglement and quantum superposition on a firmer foundation. Thus, further progress in achieving mastery over the precise flexible manipulation of BEC states could demonstrate that quantum contextuality might be an unsuspected over-arching archetypal principle in nature, leading to new insight in regards to the interpretation of quantum mechanics as applied to all levels of nature. Moreover, it will be shown that this concealed and hence heretofore unsuspected contextual aspect of natural laws, as exemplified by the dynamics underlying BEC structure, could be brought to bear to account for physical anomalies inexplicable using current paradigms, such as the claimed energy yields from low-energy nuclear reactions (as represented by the so-called process of “cold fusion”), making this phenomenon more tractable and rendered less controversial.

A Data-driven Online Identification and Control Optimization Approach applied to a Hybrid Electric Powertrain System

AbstractWithin this contribution the optimization of the electric current flow control within a hybrid electric powertrain system and hence its power and energy management strategy is introduced. This contribution describes the control optimization . Power and energy management are methods applied to hybrid electric powertrain systems to be used in modern vehicles. Hereby the electric current flow within the powertrain, i.e. between its system components, is controlled regarding predefined control objectives such as the power or energy availability with respect to a load profile. In this contribution an online-applicable optimization method of the power and energy management strategy is introduced. Its realization contains a system identification algorithm capable of being implemented within online applications and, based on this, a suitable control optimization including a predictive approach. The control objectives to be optimized in this context are the energy consumption, the power availability, and deterioration aspects of the system and its components. The algorithm is demonstrated using the example of a fuel cell/supercap-based hybrid electric powertrain system. After a brief description of the system and operation details, the results of the identification process in relation to the real behavior as well as the optimization algorithm are presented. Applying typical driving cycles to this system it can be shown that a significant improvement of this approach compared with classical power and energy methods can be achived. The main scientific and practical question remains: what can be assumed about the future behavior of the workload (applied to the system) and how can the control be optimized for the unknown future behavior. Mathematically expressed: How exact the system behavior has to be identified (from the last measurements) in relation to the principally unknown character of the upcoming future load in relations to the different optimization goals.

A Parallel Energy-Sharing Control Strategy for Fuel Cell Hybrid Vehicle

This paper presents a parallel energy-sharing control strategy for the application of fuel cell hybrid vehicles (FCHVs). The hybrid source discussed consists of a fuel cells (FCs) generator and energy storage units (ESUs) which composed by the battery and ultracapacitor (UC) modules. A direct current (DC) bus is used to interface between the energy sources and the electric vehicles (EV) propulsion system (loads). Energy sources are connected to the DC bus using of power electronics converters. A total of six control loops are designed in the supervisory system in order to regulate the DC bus voltage, control of current flow and to monitor the state of charge (SOC) of each energy storage device at the same time. Proportional plus integral (PI) controllers are employed to regulate the output from each control loop referring to their reference signals. The proposed energy control system is simulated in MATLAB/Simulink environment. Results indicated that the proposed parallel energy-sharing control system is capable to provide a practical hybrid vehicle in respond to the vehicle traction response and avoids the FC and battery from overstressed at the same time.

Modelling and simulation of voltage source converter-based interphase power controller as fault-current limiter and power flow controller

In this study, a new FACTS device is proposed, which is based on the topology of the conventional interphase power controller (IPC). The proposed topology replaces the conventional phase-shifting transformers (PSTs) with the static synchronous series compensator. The equivalent circuit model for this new voltage source converter-based IPC (VSC-based IPC) is developed. Although the injected voltages of SSSCs are almost perpendicular to the branch currents and cannot maintain a constant amplitude line voltage as PSTs, it is shown that the VSC-based IPC can effectively control the line power flow, without exceeding the line voltage regulation limits. Based on the simulations, the abilities of the device for the short-circuit current mitigation and power flow control are presented for the Iran electric network.

Ionic current flow through ZnO nanotubes

The control of ionic current (electrolyte) flow through zinc oxide (ZnO) nanotubes isinvestigated. We studied a structure operating like a field effect transistor with a tunableionic flow. The main investigation tool used was molecular dynamics simulation. Wecomplemented the molecular dynamics simulation with the site binding method in orderto study the effect of the double layer on the ionic current flowing through thenanotube. We achieved this by considering the electrolyte solution as a virtualsemiconductor wire. The double layer capacitance and surface charge of the innerwalls of the ZnO nanotube have been calculated. The results indicate that ZnOnanotubes can be tuned to operate as ion selectors. ZnO nanotubes exhibit enhancedfunctionality with characteristics similar to those of the nanopore membrane.

A simple framework of utility max-min flow control using sliding mode approach

Motivated by the limitations of current optimal flow control approach, we develop a new utility max-min flow control framework using classic sliding mode control. It consists of a source algorithm and a binary congestion feedback mechanism, in which only the sources with the highest utility at each congested link are required to reduce their transmission rates. It can be directly applied to a multi-service network with heterogeneous applications that have different QoS characteristics. The proposed framework achieves the utility max-min fairness among applications efficiently in the sense of low overhead and rapid convergence. Rigorously, the system is proven to be asymptotically stable by means of Lyapunov's theorem.

Multilayered Semiconductor Membranes for Nanopore Ionic Conductance Modulation

We explore the possibility of using thin layered semiconductor membranes for electrical control of the ion current flow through a nanopore, thereby operating like tunable ionic transistors. While single layer semiconductor membranes can be voltage tuned to operate as ionic filters or "switches", double layered membranes can rectify the ion current flowing through the nanopore in addition to ion filtering. Triple layer membranes exhibit enhanced functionality with characteristics similar to those of the single and double layer membranes in addition to bidirectional current blocking and switching, thereby operating similar to tunable ionic transistors.

Proposal for a graphene-based current nanoswitch

We propose a graphene-based model nanoswitch for the control of current flow. The deviceis made up of a graphene nanoribbon with a longitudinal semi-infinite septum on its leftside. The septum defines two terminals, where the current can be selectively directed bymeans of a high magnetic field and an adjustable potential step induced by a top gate. Thedevice’s working mechanism is based on the spatial chirality of currents in high magneticfields and on the possibility of determining the electron-like or hole-like nature of theparticles involved in transport by means of the adjustable potential step. The role ofcritical parameters such as the width of the ribbon and the presence of disorder arediscussed.

Liquid-state field-effect transistors using electrowetting

The authors report the demonstration of transistor action in the liquid state. The control of current flow in a liquid field-effect transistor (LiquiFET) was achieved by electrowetting between competitive insulating/conducting fluids. The LiquiFET structure included dielectric/hydrophobic layers, source/drain regions, a gate electrode, and hydrophilic/hydrophobic grids to contain the liquids. For a 400μm long channel, turn-on occurs at 2.5–3V drain voltage. On/off current ratios >10000:1 were measured. Linear gate voltage control over drain current was obtained with a transconductance up to 40nS. A calculated channel mobility of ∼1cm2∕Vs indicates that electronic charge transport dominates transistor operation.

Experimental Approaches for Controlling Current Flowing through Metal–Molecule–Metal Junctions

AbstractTwo experimental approaches that enable control of current flow through metal–molecules–metal junctions are described. A number of studies using two‐electrode metal–molecules–metal junctions have shown that the current between the electrodes depends on the structures of the incorporated molecules. When a tunneling mechanism dominates electron transport through organic molecules, the molecules behave similar to resistors with resistivities that can be controlled by changing the structure. Incorporation of molecules with increasing conjugation into Hg‐based junctions increases the current flow dramatically. Alternatively, by using four‐electrode electrochemical junctions that allow the potential of the electrodes to be controlled with respect to the energy levels of the incorporated molecules, it is possible to change the mechanism of electron transfer and produce abrupt increases in the current flow. These signals, analogous to solid‐state diodes, are particularly significant for molecular electronics. Electrochemical junctions also permit prediction of the value of the applied potential at which the current will start taking off and to identify the mechanism of charge transport. New and recently published results obtained using junctions based on Hg electrodes in an “electrochemical” mode show that two junctions incorporating redox centers by different interactions behave as current switches, with the current flow dominated by different charge‐transport mechanisms.

Modeling the Effects of a Swirling Flow on Temperature Stratification of Liquid Steel and Flotation of Inclusions in a Tundish

A conventional ladle shroud (LS) is compared with a swirling ladle shroud (SLS) from the points of view of fluid flow dynamics and removal ratio of inclusions from liquid steel flowing through a tundish using water modeling and fluid dynamics approaches. In this tundish the LS generates vortexing flows at the tundish outlets that disappear with the existence of high temperature gradients inside the liquid phase. On the other hand, the SLS avoids efficiently the formation of vortexes and recirculating flows either under isothermal and non-isothermal conditions. Buoyancy forces generated by changes of liquid density enhance upward velocities enhancing the flotation rate of inclusions. The conventional shroud does not promote this effect due to the existence of the vortexing flows. Eventually the LS would drive the fluid toward the bath surface forming entrainment of slag particles by liquid steel while the SLS yields a low turbulent entry jet. The SLS is a good alternative to substitute the current flow control devices available in the market.

Identification of the Impedance Model of an Implanted Cochlear Prosthesis From Intracochlear Potential Measurements

Those suffering from a severe to profound sensorineural hearing loss can obtain substantial benefit from a cochlear implant prosthesis. An electrode array implanted in the inner ear stimulates auditory nerve fibers by direct injection of electrical current. A major limitation of today's technology is the imprecise control of intracochlear current flow, particularly the relatively wide spread of neural excitation. A better understanding of the intracochlear electrical fields is, therefore, required. This paper analyzes the structure of intracochlear potential measurements in relation to both the subject's anatomy and to the properties of the electrode array. An electrically equivalent network is proposed, composed of small lumped circuits for the interface impedance and for the cochlear tissues. The numerical methods required to estimate the model parameters from high-quality electrical potential recordings are developed. Finally, some models are presented for subjects wearing a Clarion CII device with a HiFocus electrode and discussed in terms of model reliability.

Kinetic and space charge control of current flow and voltage drops along magnetic flux tubes: 2. Space charge effects

The distribution of current‐driven electrostatic potentials along auroral magnetospheric flux tubes is studied analytically, based on the principles of quasi‐neutrality and kinetic orbital motion of electrons and ions governed by inertia, electric forces, and magnetic mirror forces. When certain particle accessibility conditions are fulfilled, the kinetics determines the electron and ion number densities as unique functions of position along the flux tube and local potential. These functions are used to define potential profiles for which electron and ion number densities everywhere match, or alternatively positions where potential jumps (double layers) may occur. Magnetospheric and ionospheric particle sources in the form of Maxwellians with loss cones depending on the total voltage drop are considered, as well as trapped particles. The potential profile generally comprises a potential jump that accounts for a sizeable fraction of the total voltage drop (only by assuming unrealistic velocity distributions of the magnetospheric electron source can solutions without a jump be found). The jump may typically occur around an altitude of 1 RE, an altitude that increases with density of the ionospheric source and that decreases with increasing density of trapped, secondary, and backscattered particles and total voltage drop along the flux tube. Below the potential jump, only small potential variations occur. Above the potential jump, the potential falls off gradually, asymptotically linear in magnetic field intensity. Only a small percentage of the potential drop occurs above an altitude of a few RE, but the weak field extending to higher altitudes is essential for quasi‐neutrality and for the current‐voltage relationship (discussed in a previous paper). Above the potential jump, the number density of particles is reduced as compared to regions without current flow and potential drops. Depending on the density of the ionospheric source, solutions are possible for total potential drops much larger than the temperature of the magnetospheric electron source. While full accessibility for the mirroring electrons tends to be locally violated, accessibility for all particles within the source cone is fulfilled in these solutions, so the current‐voltage relationship does not depend on the shape of the potential profile. Some comments are also made on transient conditions when there is no time for transport of neutralizing ions from the ionosphere.

Kinetic and space charge control of current flow and voltage drops along magnetic flux tubes: Kinetic effects

The current–voltage characteristic of magnetospheric magnetic flux tubes is studied under rather general conditions, assuming the current to be carried by collision‐free particles experiencing inertia, electric forces, and magnetic mirror forces. The approach is that of the powerful kinetic “orbital motion” theory of current collectors in plasma as developed by H. M. Mott‐Smith and I. Langmuir in 1926. When C. Davisson's 1925 condition on particle access is fulfilled, the total voltage drop is uniquely determined from the current by kinetic/geometric considerations only, without considerations of the actual space charge and electrostatic potential distribution. For any velocity distribution that is isotropic within the source cone, the current–voltage characteristic is linear for sufficiently small currents. The nature of the corresponding global flux tube electric resistance is discussed. The current–voltage characteristic is given for a variety of distribution functions (where the Maxwellian case corresponds to that studied by S. Knight in 1973) including distributions with a reduced (nonisotropic) flux in the source cone. The current–voltage characteristic is also discussed for cases where the Davisson condition is not fulfilled, when the solution method provides a lower bound on the voltage for a given current. Making assumptions on the altitude extent of the voltage drop, we can also define an upper bound on the voltage for a particular current. The magnetospheric source of particles should be taken to be located at the top of the acceleration region in order to fulfill the Davisson condition. This may limit the effective magnetic mirror ratio, such that the applicability of the linear approximation to the current–voltage characteristic is more restricted, and the saturation current is moderately small, which may lead to overvoltages, a redistribution of the current, or an increased extent of the acceleration region. Joining solutions that piecewise fulfill the Davisson condition, we can derive the current flow for a rather wide range of prescribed potential distributions. Earlier works on the Knight mechanism and related theories for determining the voltage drop along a flux tube are discussed. Determination of the electrostatic potential distribution, and verification of the Davisson condition, requires considerations of the space charge (Poisson equation), to be discussed in a second paper.

System and method for controlling electrical current flow as a function of detected sound volume

A system and method for selectively controlling an electrical component is claimed. The system contains an audio detector, such as a microphone, that receives sound energy and converts the sound energy into a corresponding electrical signal. The content of the sound energy is irrelevant. Rather, it is the volume of the sound energy that is to be represented by the electrical signal. To produce an electrical signal that corresponds to noise volume, the amplitude of the electrical signal is amplified. The amplified signal is then rectified and filtered, thereby producing a D/C electrical signal that is representative of the volume of the sound energy detected. The D/C electrical signal is used to selectively regulate a current flow controller. The current flow controller controls the flow of current to the electronic component.

TCP flow control technique for an interworking interface: hardware implementation

Current TCP flow control depends on packet losses to find the workload that a network can support. A variety of situations, including lossy wireless networks, asymmetric networks and web traffic workload, violates many of the assumptions made by TCP, causing degraded end-to-end performances. To improve the performance of TCP over heterogeneous networks (Ethernet and ATM interconnection), we propose a new technique, which we call Vegas–Snoop+, based on Vegas and Snoop protocols. Two modified service elements take part on the Vegas–Snoop+ technique. First, Vegas service element manages the connection parameters to achieve better throughput. Second, Snoop service element isolates the Ethernet senders from the characteristics of the ATM link. The objective in this paper is to win from advantages of Vegas and Snoop protocols, as well as to search an interconnection interface for networks interoperability. Actually, the development of two new integrated circuits (the BCM5680 (switch) and the BCM5401 (PHY)) orientate researchers to implement, at higher layer of the OSI model, flow control mechanisms to ensure reliability. Vegas–Snoop+ is an implementation of TCP, which gives in this way a solution for traffic management and congestion control improving good throughput with more reliability.

Phantom: a simple and effective flow control scheme

This paper presents Phantom, a simple constant space algorithm for rate-based flow control. As shown by our simulations, it converges fast to a fair rate allocation while generating a moderate queue length. While our approach can be easily implemented in ATM switches for managing available bit rate (ABR) traffic, it is also suitable for flow control in TCP router-based networks. Both the introduced overhead and the required modifications in TCP flow control systems are minimal. The implementation of this approach in TCP guarantees fairness and provides a unifying interconnection between TCP routers and ATM networks. The new algorithm easily inter-operates with current TCP flow control mechanisms and thus can be gradually introduced into installed-based TCP networks.

Phantom

This paper presents Phantom , a simple constant space algorithm for rate based flow control. As shown by our simulations, it converges fast to a fair rate allocation while generating a moderate queue length. While our approach can be easily implemented in ATM switches for managing ABR traffic, it is also suitable for flow control in TCP router based networks. Both the introduced overhead and the required modifications in TCP flow control systems are minimal. The implementation of this approach in TCP guarantees fairness and provides a unifying interconnection between TCP routers and ATM networks. The new algorithm easily inter-operates with current TCP flow control mechanisms and thus can be gradually introduced into installed based TCP networks.

A MINIATURIZED APPROACH TO THE CRYOELECTRONIC MAGNETIC FIELD EFFECT TRANSISTOR

Magnetic control of the filamentary current flow during avalanche breakdown in bulk semiconductors at low temperatures represents an interesting operation principle for the design of a magnetic field effect transistor. We have experimentally verified miniaturized device configurations using superconducting lines for the generation of the magnetic control field and all interconnections. The evaluation of the important performance characteristics of our transistor concept looks highly promising.