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A new model of space-time is proposed that incorporates the properties of a random resistor network. The self-similar nature of such networks is particularly useful in extrapolating force interactions to different levels of scale. By modeling time and matter as current and resistance, respectively, a simple equation for mass, time, and motion is derived that provides a novel mechanism for the displacement of matter. Keywords: Random resistor network, space-time, redshift, gravity, speed of light, Introduction Recent cosmological observations suggest that prevailing models of space-time may not adequately describe certain phenomena, thus inviting the formulation of alternative constructs that address these unresolved issues [1-3]. To [...]

A qualitative description of energy transfer from a battery to a resistor using the Poynting vector was recently published. We make this argument quantitative by considering a long current carrying wire and showing that the energy transferred across a plane perpendicular to the wire is equal to the Joule heating in the wire beyond this plane. [c] 2010 American Association of Physics Teachers. [DOI: 10.1119/1.3456567]

This paper proposes a new method to decrease the absolute value of temperature coefficient of resistance (TCR) in P-type boron implanted polysilicon resistors, at a given intermediate sheet resistance values, by selecting an optimized combination of boron doping implant conditions with co-implantation conditions. The co-implantation ion species that were investigated are fluorine, argon and xenon. Each of the co-implantation species was studied at three different co-implantation conditions and two different boron doping implant conditions of dose and energy. The stopping and range of ions in matter (SRIM) Monte Carlo simulation and thermawave measurements were used in order to set the experimental conditions and to evaluate the crystal damage and the amorphous layer depth created by the co-implantation. Amorphous layer is defined in this work as highly disordered material with vacancies concentration above 10% of the crystal density. Electrical measurements show that co-implantation causes a remarkable change in sheet resistance and TCR. Deeper co-implanted amorphous layer increases TCR and decreases sheet resistance. Typical polysilicon TCR is negative, while the TCR of a single crystal is positive. An improvement of TCR is defined at this work as minimum TCR in absolute values, which is lower sensitivity of sheet resistance to operational temperatures. Co-implantation that created deep amorphous layer in the polysilicon, decreases the TCR absolute values by up to ~75% at the lower boron doping implant samples. Deep co-implanted amorphous layer also decreases sheet resistance by up to ~40% in both of the boron doping implants. Co-implanted xenon and fluorine exhibit similar effect on sheet resistance and TCR, while the co-implanted argon effect is weaker in comparison to samples without co-implantation. The increase of TCR and the decrease of sheet resistance are attributed to grains regrowth during the rapid thermal anneal (RTP). The regrowth of the co-implanted amorphous layer creates larger grains with less grain boundaries and less defects in comparison to the polysilicon samples without co-implantation. Analysis by X-ray diffractometer (XRD) and atomic force microscope (AFM) supports the suggested model. Index Terms--AFM, amorphization, atomic force microscope, co-implantation, grain boundary, grains regrowth, P-type polysilicon, rapid thermal anneal, recrystalization, RTP, sheet resistance, SRIM, TCR, temperature coefficient of resistance, thermawave, X-ray diffractometer, XRD.

We report a new design and operation of a microelectromechanical systems (MEMS) differential scanning calorimeter (DSC) for heat-capacity measurements. The sensor consists of a 500-nm silicon nitride membrane supported by four bridges on a silicon wafer. On one side of the membrane, a serpentine-shaped platinum layer is deposited and used as both a resistive heater and a thermometer during the DSC measurement. This MEMS design can provide a self-alignment between the DSC cell and the material to be analyzed in order to prevent its deposition on the sloping side walls of the silicon frame. According to FEM calculations, the system exhibits good thermal isolation and high uniformities in the temperature field in the sensing area of the device. To evaluate the use of this calorimetric device for liquid samples, we measure the heat of vaporization of nanoliter-scale water droplets with high preciseness using the calorimeter in both scanning and heat conduction modes. [2008-0288] Index Terms--Calorimetry, heat capacity, microelectromechanical systems (MEMS).

The parasitic factors that strongly influence the measurement accuracy of Cross-Bridge Kelvin Resistor (CBKR) structures for low specific contact resistances (Pc) have been extensively discussed during last few decades and the minimum of the Pc value, which could be accurately extracted, was estimated. We fabricated a set of various metal-to-metal CBKR structures with different geometries, i.e., shapes and dimensions, to confirm this limit experimentally and to create a method for contact metal-tometal interface characterization. As a result, a model was developed to account for the actual current flow and a method for reliable Pc extraction was created. This method allowed to characterize metal-to-metal contact interface. It was found that in the case of ideal metal-to-metal contacts, the measured CBKR contact resistance was determined by the dimensions of the two-metal stack in the area of contact and sheet resistances of the metals used. Index Terms--Cross-bridge Kelvin resistor (CBKR), metal-to-metal contacts, specific contact resistance.

A family of tunable MOS resistors based on quasi-floating-gate (QFG) transistors biased in the triode region is analyzed in this paper. From the study results, a new device that outperforms previous implementations, is presented. By means of a capacitive divider, the ac component of the drain-to-source voltage scaled with a factor [alpha] [less than or equal to] 1 is added to the gate-to-source voltage leading to a cancellation of the nonlinear terms. The effect of [alpha] on resistor linearity is analytically studied. Simulation results are also provided for different technologies. Finally, a complete transconductor has been built which preserves the linearity of the MOS resistor. Three versions of the transconductor have been fabricated for different values of [alpha] ([alpha] = 0, 0.5, and 1) in a 0.5 [micro]m CMOS technology with [+ or -] 1.65-V supply voltage. Experimental results show (for [alpha] = 1) a THD of -57 dB (HD2 = -70 dB) at 1 MHz for 2-V peak-to-peak differential input signal with a nominal ac-transconductance of 200 [micro]A/V and a power consumption of 3.2 mW. Index Terms--Analog CMOS circuits, linear resistors, low-power and low-voltage CMOS circuits, operational transconductance amplifier (OTA), quasi-floating-gate (QFG) transistors.

Piecewise constant (PWC) waveforms consisting of amplitude-modulated edges (AMEs) are an important signal family in optical communication technology. The sampling of PWC signals by an analog-to-digital converter (ADC) requires an extremely high sampling rate. In this paper, we show that PWC signals can be measured and reconstructed using a parallel capacitor-resistor network (PCRN). The reconstruction of the amplitudes and arrival times of p AMEs occurring during one sampling period is possible using 2p parallel CR-filters whose outputs are simultaneonsly sampled. The PCRN significantly reduces the sampling rate of the ADC, and the reconstruction algorithm is manageable on microprocessor and very large scale integration circuits. We describe several variations and applications of the PCRN sampling scheme. Index Terms--Analog-to-digital converters (ADCs), microprocessors, piecewise constant (PWC) signals, very large scale integration (VLSI).

This paper introduces a picoliter droplet dispenser relying on an array of silicon microcantilevers. The microcantilevers bear fluidic channels, and liquid transfer is achieved by a direct contact of the cantilever tip and the surface. A high degree of control over the location and geometry of the fabricated patterns is ensured by incorporating force sensors and electroassisted deposition means, i.e., electrowetting actuation and electrospotting, to the devices. The cantilever array, a PC-controlled stage, and an electronic circuit dedicated to the piezoresistance measurements form a closed-loop system that enables the automatic displacement of the array and the control of the deposition parameters. By using an external loading chip, different liquids are loaded onto the cantilevers, enabling the parallel deposition of several entities in a single spotting run. This paper details the design of the cantilevers assisted by finite-element modeling, the fabrication of the cantilever array, and the closed-loop operation. Moreover, proof-of-concept experiments are presented to demonstrate the versatility of our deposition system in terms of deposited materials and spot sizes. The control of the spotting process, the versatility of the printed materials, and the added electroassisted features prove that this tool has a real potential for research work and industrial applications. [2008-0038] Index Terms--Droplet, electrodeposition, electrowetting, micro-cantilever, piezoresistor, surface patterning.

We developed a method for use of accelerometers and force sensing resistors (FSRs) within an optimal controller of walking for hemiplegic individuals. The data from four dual-axis accelerometers and four FSRs were inputs, while six muscle activation profiles were outputs. The controller includes two stages: 1) estimating the target gait pattern using artificial neural networks; and 2) optimal control minimizing tracking errors (from the estimated gait pattern) and muscle efforts. The controller was tested using data collected from six healthy subjects walking at five speeds (0.6-1.4 m/s). The average root mean square errors (RMSEs) normalized by the peak-to-peak value of the target signals [normalized RMSE (NRMSE)] were below 6%, 7%, 8%, and 3% for estimation of joint angles, hip acceleration, ground reaction force, and movement of the center of pressure, respectively. Using the estimated data as inputs, the simulation generated the target healthy-like gait patterns and reproducible muscle activation profiles in 90% of 300 tested gait trials. Overall tracking NRMSE was between 2% and 9%. The optimal controller was developed for testing the feasibility of healthy-like gait patterns in hemiplegic individuals, and generating a knowledge base that is required for the synthesis of a sensory-driven control of walking assisted by functional electrical stimulation. Index Terms--Artificial neural networks (ANNs), functional electrical stimulation (FES), gait, machine learning, optimal control, sensory system.

In this paper, an implementation of a tunable highly linear floating resistor that can be fully integrated in CMOS technology is presented. The second-order effects of a single MOS transistor operating in the triode operation regime are described, and a common-mode finearization technique is applied to suppress these nonlinearities. This technique is implemented by utilizing a low-power circuit design strategy that exploits the capacitive coupling and the charge storage properties of floating-gate transistors. The resistance of the proposed circuit is tuned by utilizing the Fowler-Nordheim tunneling and hot-electron injection quantum-mechanical phenomena. We demonstrate the use of this resistor in highly linear amplifier. We present experimental data from the chips that were fabricated in a 0.5-[micro]m CMOS process. We show that this resistor exhibits 0.024% total harmonic distortion (THD) for a sine wave with [1-V.sub.pp] amplitude. Also, we show the programmability of the amplifier gain using the proposed tunable resistor. Index Terms--CMOS, floating gate, resistor, tunable.

This paper presents an approach and associated circuitry for harvesting near maximum output power from electromagnetic waves in the RF/microwave region of the spectrum with variable incident power densities in the range of tens of [micro]W/[cm.sup.2]. It is shown that open loop resistor emulation at the input port of a power converter is a suitable solution for tracking the peak power point of a low-power rectifying antenna source over a wide range of incident RF power densities. A boost converter with a simple low-power control approach for resistor emulation is presented. A hardware design example with detailed efficiency analysis is given using commercially available discrete circuitry. Experimental results are presented for a system harvesting 420 [micro]W to 8 [micro]W from a 6 cm x 6 cm rectifying antenna with incident RF power ranging from 70 [micro]W/[cm.sup.2] to 30 [micro]W/[cm.sup.2], respectively. The results demonstrate that resistor emulation is a simple and practical approach to energy harvesting with variable low-power radiative RF sources. Index Terms--DC-DC, low power, maximum power point tracking, resistor emulation, RF energy harvesting.

A novel chemiresistor sensor for detection of organic analytes in high-conductivity aqueous electrolyte solution is reported. The chemiresistor sensor is based on thin films of gold nanoparticles capped with a 1-hexanethiol monolayer that is inkjet printed onto a microelectrode. In order for a change in nanoparticle film resistance to be measured, the electronic conduction must preferentially occur through the nanoparticle film rather than through the high-conductivity electrolyte solution. This was achieved by miniaturizing the chemiresistor device such that the double layer capacitance of the electrodes in contact with the electrolyte solution gives rise to a significantly larger impedance compared to the nanoparticle film resistance. This system was shown to be sensitive to simple organics dissolved in an aqueous electrolyte solution. The organic analytes, dissolved in the aqueous solution, partition into the hydrophobic nanoparticle film causing the nanoparticle film to swell, resulting in an increase in the low-frequency impedance of the sensor. An increase in the impedance, at 1 Hz, of the gold nanoparticle chemiresistor on exposure to toluene, dichloromethane, and ethanol dissolved in 1 M KCl solution was demonstrated with detection limits of 0.1, 10, and 3000 ppm, respectively. Titration curves over 3 orders of magnitude could be obtained for analytes such as toluene.

Fault ride-through (FRT) is required for large wind farms in most power systems. Fixed speed wind turbines (FSWTs) are a diminishing but significant sector in the fast-growing wind turbine (WT) market. State-of-art techniques applied to meet grid requirements for FSWT wind farms are blade pitching and dynamic reactive power compensation (RPC). Blade pitching is constrained by the onerous mechanical loads imposed on a wind turbine during rapid power restoration. Dynamic RPC is constrained by its high capital cost. These present technologies can therefore be limiting, especially when connecting to smaller power systems. A novel alternative technology is proposed that inserts series resistance into the generation circuit. The series dynamic braking resistor (SDBR) dissipates active power and boosts generator voltage, potentially displacing the need for pitch control and dynamic RPC. This paper uses a representative wind farm model to study the beneficial effect of SDBR compared to dynamic RPC. This is achieved by quasi-steady-state characterization and transient FRT stability simulations. The analysis shows that SDBR can substantially improve the FRT performance of a FSWT wind farm. It also shows that a small resistance, inserted for less than one second, can displace a substantial capacity of dynamic RPC. Index Terms--Dynamic braking resistors, fault ride-through, wind farm stability, wind turbine generators.

This paper presents the derivation procedure used in determining the parameters in SiGe HBT's small-signal model where the Pi circuit configuration is employed. For both the transistor's external base--collector capacitor and its base spreading resistor, new close-form expressions have been derived. Comparisons with existing approaches vindicate the feasibility and effectiveness of our formulations. With the impact of the lossy substrate effectively modeled and the frequency dependency of the transconductance properly addressed, this proposed extraction approach demonstrates accurate results up to 30 GHz with different bias conditions. Index Terms--Base spreading resistor, HBT, Pi model, SiGe.

The measurement of recovery times of Y123 thin films under various conditions is discussed. Results suggest that the recovery time is dependent on operating time, current value and resistance of the parallel resistor.

The charge pump (CP) circuit is a key element in a phase-locked loop (PLL). Its function is to transform the Up and Down signals from the phase/frequency detector into current. In CMOS CPs, which have Up and Down switches made of p-channel MOS and n-channel MOS, respectively, a current mismatch occurs when dumping the charge to the loop filter. This current mismatch of the CP in the PLL generates fluctuations in the voltage-controlled-oscillator input and subsequently, a large phase noise on the PLL output signals. In this brief, a new CP with good current matching characteristics is proposed. By using a simple gain-boosting circuit, good current matching characteristics can be achieved with less than 0.1% difference of the Up/Down current over the CP output voltage ranges of 0.8-2.2 V and 0.5-1.2 V on 0.35-[micro]m 3.3-V and 0.18-[micro]m 1.8-V CMOS processes, respectively. The proposed CP circuit is simulated and verified by HSPICE with 0.35-[micro]m 3.3-V and 0.18-[micro]m 1.8-V CMOS parameters. Index Terms--Gain-boosting charge pump (CP), phase-locked loop (PLL), voltage-controlled resistor.

A current feedback amplifier (CFA) has good high-speed properties but its performance is very dependent on interconnect designs, particularly its feedback interconnect design. In this brief, effects of the location of a feedback resistor in the feedback interconnect design of a CFA are analyzed in the frequency domain. A transfer function of a CFA is derived, and frequency responses are simulated by varying the location of a feedback resistor in the transfer function. Then, experiments are carried out with test circuits consisting of CFAs with diverse locations. It can be seen that further distance of the resistor to the inverting input of the CFA results in larger distortion of the CFA's frequency response. This result is true even if the total length of the feedback interconnect is constant. Index Terms--Current feedback amplifier (CFA), feedback interconnect, feedback resistor, frequency-domain analysis.

This paper analyzes the effect of the coordination of optimal reclosing and fuzzy logic-controlled braking resistor on the transient stability of a multimachine power system in case of an unsuccessful reclosing of circuit breakers. The transient stability performance of the coordinated operation of optimal reclosing and fuzzy controlled braking resistor is compared to that of the coordinated operation of conventional auto-reclosing and fuzzy controlled braking resistor. The effectiveness of the proposed method is confirmed by simulations in case of a nine-bus power system model as well as a ten-machine system. Simulation results of both balanced and unbalanced faults at different points in the power systems show that the coordinated operation of optimal reclosing and fuzzy controlled braking resistor is able to stabilize the systems well in case of an unsuccessful reclosing. Moreover, the transient stability performance of the coordinated operation of optimal reclosing and fuzzy controlled braking resistor is better than that of the coordinated operation of conventional auto-reclosing and fuzzy controlled braking resistor. Index Terms--Balanced fault, braking resistor (BR), fuzzy controller, global positioning system (GPS), optimal reclosing, power system transient stability, unbalanced faults, unsuccessful reclosing.

In this paper, premature damage to some static inverter loading resistor modules is analyzed. Furthermore, investigations were carried out to determine the origins and causes of this serious damage occurring on the resistor modules in service. Investigations were preformed on the insulating liquid samples as well as new resistor modules. From the results obtained, it seems that the origin of the damage is from a long-standing, free-burning arc between two resistor windings, following mechanical breakdown. Index Terms--Dielectric liquids, electric breakdown, arc heating, bubbles, fault diagnostic.

Interpolating, dual resistor ladder digital-to-analog converters (DACs) typically use the fine, least significant bit (LSB) ladder floating upon the static most significant bit (MSB) ladder. The usage of the LSB ladder incurs a penalty in dynamic performance due to the added output resistance and switch matrix parasitic capacitance. Current biasing of the LSB ladder addresses this issue by employing active circuitry. We propose an inverted ladder DAC, where an MSB ladder slides upon two static LSB ladders. While using no active components this scheme achieves lower output resistance and parasitic capacitance for a given power budget. We present a 0.35-[micro]m, 3.3-V implementation consuming 22-[micro]A current with output resistance of 40 k[ohm] and effective parasitic capacitance of 650 fF. Index Terms--Digital-to-analog converter (DAC), low power, resistor ladder.

Circuit techniques using resistor strings (R-strings) and resistor rings (R-rings) for phase averaging and interpolation are described. Phase averaging can reduce phase errors, and phase interpolation can increase the number of available phases. In addition to the waveform shape, the averaging and the interpolation performances of the R-strings and R-rings are determined by the clock frequency normalized by a RC time constant of the circuits. To attain better phase accuracy, a smaller RC time constant is required, but at the expense of larger power dissipation. To demonstrate the resistor ring's capability of phase averaging and interpolation, a 125-MHz 8-bit digital-to-phase converter (DPC) was designed and fabricated using a standard 0.35-[micro]m SPQM CMOS technology. Measurement results show that the DPC attains 8-bit resolution using the proposed phase averaging and interpolation technique. Index Terms--Averaging, clocks, delay-locked loops (DLLs), interpolation, phase-locked loops (PLLs).

In this paper, a supervisory two-layer control structure is synthesized with network elements as control means for thyristor-controlled braking resistor (BR) of multimachine power system operating in transient emergency state. This creates a nmltiple local feedback controller that can be realistically implemented using only local measurements and whose performance is consistent with respect to changes in network configuration, loading, and power transfer conditions. Following a major disturbance, the rotor angle and rotor speed of each generator unit are determined and the firing angle of the thyristor switch associated with the BR is computed by the local controllers. By controlling the firing angle of the thyristor, the BR controls the accelerating power in each generator and, thus, enhances the stability margins and damping oscillations. Since the local controllers rely only on measurements particular to their own subsystem, interconnection effects and the nonlinearities introduced by them are accounted for by the supervisory layer. The two-layer controller was tested on the IEEE Western States Coordinating Council (WSCC) test system. Results show that the controller is capable of bringing the system under control when starting with inherently unstable conditions, even when the severity of the disturbances is increased. Index Terms--Braking resistor (BR), firing angle, hierarchical structure, optimal control, thyristor switch, transient stability crisis.

Accurate modeling and efficient parameter extraction of a scalable lumped-element model for n-well meander-line resistors that are suitable for radio frequency integrated circuit (RFIC) applications are presented. It is concluded that the scalable model, with its model parameters can be easily implemented in a subcircuit in SPICE or SpectreRF, making this good physical model for the RF circdcouit designer.

The use of epitaxial titanium nitride (TiN) thin films for resistors are investigated inorder to extend the application range of epitaxial niobium nitride (NbN) devices, as they have about the same lattice constant and crystalline structure as NbN and magnesium oxide (MgO). The fabrication of TiN resistors for epitaxial NbN devices is described.

The viability of using gold damping resistors with YBCO dc SQUIDs, connected through in situ gold/YBCO contacts deposited by laser ablation on 24degree strontium titanate (STO) bicrystal substrates is reported. It is shown that this technique enhances the normalized voltage modulation, compared to the undamped counterparts at 77 K.