Transfer Circuit Research Articles

The fault-tolerance study of QCA adder based on probability model

The probability models of 2 different quantum cellular automaton (QCA) adders are based on the theory of probabilistic transfer matrix and circuit partition. The effect of individual component on the overall fault-tolerance is fully analyzed at the same level. The simulation shows that the effect of the wire is minor when the success probability is low, while the overall fault-tolerance rises sharply once the success probability is high. And the inverter is considered to be a major factor that affects the overall fault-tolerance in the variation range of parameter. Frobenbius norm of the overall error probabilistic transfer matrix is employed to study the fault-tolerance difference. The result shows that the overall fault-tolerance of QCA adder consisting of 5-input majority is superior to the other. Such fault-tolerance analyses should be used for a better characterization of QCA circuit design and fault-tolerance improvement.

Resistance and relatedness on an evolutionary graph

When investigating evolution in structured populations, it is often convenient to consider the population as an evolutionary graph-individuals as nodes, and whom they may act with as edges. There has, in recent years, been a surge of interest in evolutionary graphs, especially in the study of the evolution of social behaviours. An inclusive fitness framework is best suited for this type of study. A central requirement for an inclusive fitness analysis is an expression for the genetic similarity between individuals residing on the graph. This has been a major hindrance for work in this area as highly technical mathematics are often required. Here, I derive a result that links genetic relatedness between haploid individuals on an evolutionary graph to the resistance between vertices on a corresponding electrical network. An example that demonstrates the potential computational advantage of this result over contemporary approaches is provided. This result offers more, however, to the study of population genetics than strictly computationally efficient methods. By establishing a link between gene transfer and electric circuit theory, conceptualizations of the latter can enhance understanding of the former.

Effect of Channel Depth of PEM Fuel Cell on its Peformance

The electrode structure, especially for the channel depth, plays an important role on the performance of the proton exchange membrane (PEM) fuel cell. In this paper, the performance and electrochemical impedance of the PEM fuel cell are measured experimentally. The simulation results of mass transfer and equivalent circuit for the electrochemical impedance are used to explain the effect of the channel depth on the performance of the PEM fuel cell. These results show that when the cell temperature is lower than the gas humidification temperatures, the performance of PEM fuel cell with the channel depth of 2mm is better than that of 1mm; there is more liquid water saturation in cathode for the channel depth of 1mm than that for the channel depth of 2mm. The charge transfer resistance of the PEM fuel cell with the channel depth of 2mm is less than that with the channel depth of 1mm. These results are very helpful to optimizing structure of the PEM fuel cell.

Determining the optimum cyclic operation of adsorption chillers by a direct method for periodic optimal control

Adsorption refrigeration systems provide a sustainable possibility to reduce the environmental impact of refrigeration and air-conditioning as they allow for sources of otherwise unused excess waste heat to be reused for cooling purposes. Adsorptive cooling is a discontinuously operated cycling process, and it is well known that the determination of an optimal cycling time yielding maximum cooling power is a key to the design of an efficient mode of operation. The optimal cycle time however strongly depends on operating conditions such as ambient air temperature, available heat source temperature, desired target cooling temperature, and achievable volume flow rates of the secondary heat transfer circuits. In this contribution, we apply a direct method for periodic optimal control to optimize two-bed adsorption chillers. We present a first principles dynamic model of the underlying thermal process. We show that direct methods for periodic optimal control allow for quick and reliable computation of optimal cycle times for a given set of parameters. Contrary to pre-existing methods, fast computation times and guaranteed optimality of the solutions computed by our approach makes it viable to extensively study the simulated optimal cyclic operation of two-bed adsorption chillers under a wide range of varying conditions.

A Fully-Implantable Wireless System for Human Brain-Machine Interfaces Using Brain Surface Electrodes: W-HERBS

The brain-machine interface (BMI) is a new method for man-machine interface, which enables us to control machines and to communicate with others, without input devices but directly using brain signals. Previously, we successfully developed a real time control system for operating a robot arm using brain-machine interfaces based on the brain surface electrodes, with the purpose of restoring motor and communication functions in severely disabled people such as amyotrophic lateral sclerosis patients. A fully-implantable wireless system is indispensable for the clinical application of invasive BMI in order to reduce the risk of infection. This system includes many new technologies such as two 64-channel integrated analog amplifier chips, a Bluetooth wireless data transfer circuit, a wirelessly rechargeable battery, 3 dimensional tissue-fitting high density electrodes, a titanium head casing, and a fluorine polymer body casing. This paper describes key features of the first prototype of the BMI system for clinical application.

Modular electron transfer circuits for synthetic biology

Electron transfer is central to a wide range of essential metabolic pathways, from photosynthesis to fermentation. The evolutionary diversity and conservation of proteins that transfer electrons makes these pathways a valuable platform for engineered metabolic circuits in synthetic biology. Rational engineering of electron transfer pathways containing hydrogenases has the potential to lead to industrial scale production of hydrogen as an alternative source of clean fuel and experimental assays for understanding the complex interactions of multiple electron transfer proteins in vivo. We designed and implemented a synthetic hydrogen metabolism circuit in Escherichia coli that creates an electron transfer pathway both orthogonal to and integrated within existing metabolism. The design of such modular electron transfer circuits allows for facile characterization of in vivo system parameters with applications toward further engineering for alternative energy production.

Transfer matrices and circuit representation for the semiclassical traces of the baker map

Because of a formal equivalence with the partition function of an Ising chain, the semiclassical traces of the quantum baker map can be calculated using the transfer-matrix method. We analyze the transfer matrices associated with the baker map and the symmetry-reflected baker map (the latter happens to be unitary but the former is not). In both cases simple quantum-circuit representations are obtained, which exhibit the typical structure of qubit quantum bakers. In the case of the baker map it is shown that nonunitarity is restricted to a one-qubit operator (close to a Hadamard gate for some parameter values). In a suitable continuum limit we recover the already known infinite-dimensional transfer operator. We devise truncation schemes allowing the calculation of long-time traces in regimes where the direct summation of Gutzwiller's formula is impossible. Some aspects of the long-time divergence of the semiclassical traces are also discussed.

A hardwired NoC infrastructure for embedded systems on FPGAs

A hardwired network-on-chip based on a modified Fat Tree (MFT) topology is proposed as a communication infrastructure for future FPGAs. With extremely simple routing, such an infra structure would greatly enhance the ongoing trend of embedded systems implementation using multi-cores on FPGAs. An efficient H-tree based floor plan that naturally follows the MFT construction methodology was developed. Several instances of the proposed NoC were implemented with various inter-routers links progression schemes combined with very simple router architecture and efficient client network interface (CNI). The performance of all these implementations was evaluated using a cycle-accurate simulator for various combinations of NoC sizes and traffic models. Also a new data transfer circuit for transferring data between clients and NoC operating at different (unrelated) clock frequencies has been developed. Allowing data transfer at one data per cycle, the operation of this circuit has been verified using gate-level simulations for several ratios of NoC/client clock frequencies.

Composite Yarns of Multiwalled Carbon Nanotubes with Metallic Electrical Conductivity

Unique macrostructures known as spun carbon-nanotube fibers (CNT yarns) can be manufactured from vertically aligned forests of multiwalled carbon nanotubes (MWCNTs). These yarns behave as semiconductors with room-temperature conductivities of about 5 x 10(2) S cm(-1). Their potential use as, for example, microelectrodes in medical implants, wires in microelectronics, or lightweight conductors in the aviation industry has hitherto been hampered by their insufficient electrical conductivity. In this Full Paper, the synthesis of metal-CNT composite yarns, which combine the unique properties of CNT yarns and nanocrystalline metals to obtain a new class of materials with enhanced electrical conductivity, is presented. The synthesis is achieved using a new technique, self-fuelled electrodeposition (SFED), which combines a metal reducing agent and an external circuit for transfer of electrons to the CNT surface, where the deposition of metal nanoparticles takes place. In particular, the Cu-CNT and Au-CNT composite yarns prepared by this method have metal-like electrical conductivities (2-3 x 10(5) S cm(-1)) and are mechanically robust against stringent tape tests. However, the tensile strengths of the composite yarns are 30-50% smaller than that of the unmodified CNT yarn. The SFED technique described here can also be used as a convenient means for the deposition of metal nanoparticles on solid electrode supports, such as conducting glass or carbon black, for catalytic applications.

Synthesis of a Low-Band-Gap Small Molecule Based on Acenaphthoquinoxaline for Efficient Bulk Heterojunction Solar Cells

A novel small molecule (SM) with a low-band-gap based on acenaphthoquinoxaline was synthesized and characterized. It was soluble in polar solvents such as N,N-dimethylformamide and dimethylacetamide. SM showed broad absorption curves in both solution and thin films with a long-wavelength maximum at 642 nm. The thin film absorption onset was located at 783 nm, which corresponds to an optical band gap of 1.59 eV. SM was blended with PCBM to study the donor-acceptor interactions in the blended film morphology and the photovoltaic response of the bulk heterojunction (BHJ) devices. The cyclic voltammetry measurements of the materials revealed that the HOMO and LUMO levels of SM are well aligned with those of PCBM, allowing efficient photoinduced charge transfer and suitable open circuit voltage, leading to overall power conversion efficiencies (PCEs) of approximately 2.21 and 3.23% for devices with the as-cast and thermally annealed blended layer, respectively. The increase in the PCE with the thermally annealed blend is mainly attributed to the improvement in incident photon to current efficiency (IPCE) and short circuit photocurrent (J(sc)). Thermal annealing leads to an increase in both the crystallinity of the blend and hole mobility, which improves the PCE.

Enhanced Performance of Bulk Heterojunction Solar Cells Using Novel Alternating Phenylenevinylene Copolymers of Low Band Gap with Cyanovinylene 4-Nitrophenyls

Two novel low band gap soluble copolymers, P1 and P2, were synthesized and characterized. P1 consisted of alternating dihexyloxyphenylene and α-[[4-(diphenylamino)phenyl]methylene]-4-nitro-benzeneacetonitrile. P2 consisted of alternating dihexyloxyphenylene and α,α′-[(1,4-phenylene)dimethylidyne]bis(αZ,α′Z)-4-nitrobenzeneacetonitrile. These copolymers showed broad absorption curves with long-wavelength absorption maximum around 620 nm and optical band of 1.68 and 1.64 eV for P1 and P2, respectively. Both P1 and P2 were blended with PCBM to study the photovoltaic response of bulk heterojunction (BHJ) solar cells. The highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) levels of both P1 and P2 are well aligned with those of PCBM acceptor. This allows efficient photoinduced charge transfer and high open circuit voltage, leading to an overall power conversion efficiency (PCE) of 3.15% and 2.60% for the as cast P1:PCBM- and P2:PCBM-based devices, respectively. The PCE of the devices has been further improved up to 4.06% and 3.35% for the devices based on thermally annealed P1:PCBM and P2:PCBM blends, respectively.

Grain boundaries dependent hydrogen sensitivity in MAO-TiO2 thin films sensors

Anatase TiO2 thin films were fabricated on titanium substrates by micro-arc oxidation (MAO) process and their hydrogen sensing properties were investigated. The obtained films exhibited the maximum H2 gas response at 250°C but showed no response at the temperature above 300°C. Electrochemical impedance spectroscopy (EIS) was applied to investigate the gas sensing mechanism. EIS analysis on the as-prepared MAO-TiO2 films with limited porosity reveals that the equivalent electron transfer circuit of grain and grain boundary could be represented electrochemically by a resistor and a constant phase element (CPE) in parallel, respectively, by which a possible surface-controlled gas sensing mechanism is proposed. It is found that temperature dependent grain boundary is a crucial factor governing the gas sensing properties.

Towards Fully Integrated Wireless Impedimetric Sensors

We report on the design and characterization of the building blocks of a single-chip wireless chemical sensor fabricated with a commercial complementary metal-oxide-silicon (CMOS) technology, which includes two types of transducers for impedimetric measurements (4-electrode array and two interdigitated electrodes), instrumentation circuits, and a metal coil and circuits for inductive power and data transfer. The electrodes have been formed with a polycrystalline silicon layer of the technology by a simple post-process that does not require additional deposition or lithography steps, but just etching steps. A linear response to both conductivity and permittivity of solutions has been obtained. Wireless communication of the sensor chip with a readout unit has been demonstrated. The design of the chip was prepared for individual block characterization and not for full system characterization. The integration of chemical transducers within monolithic wireless platforms will lead to smaller, cheaper, and more reliable chemical microsensors, and will open up the door to numerous new applications where liquid mediums that are enclosed in sealed receptacles have to be measured.

Insulation of a synthetic hydrogen metabolism circuit in bacteria

BackgroundThe engineering of metabolism holds tremendous promise for the production of desirable metabolites, particularly alternative fuels and other highly reduced molecules. Engineering approaches must redirect the transfer of chemical reducing equivalents, preventing these electrons from being lost to general cellular metabolism. This is especially the case for high energy electrons stored in iron-sulfur clusters within proteins, which are readily transferred when two such clusters are brought in close proximity. Iron sulfur proteins therefore require mechanisms to ensure interaction between proper partners, analogous to many signal transduction proteins. While there has been progress in the isolation of engineered metabolic pathways in recent years, the design of insulated electron metabolism circuits in vivo has not been pursued.ResultsHere we show that a synthetic hydrogen-producing electron transfer circuit in Escherichia coli can be insulated from existing cellular metabolism via multiple approaches, in many cases improving the function of the pathway. Our circuit is composed of heterologously expressed [Fe-Fe]-hydrogenase, ferredoxin, and pyruvate-ferredoxin oxidoreductase (PFOR), allowing the production of hydrogen gas to be coupled to the breakdown of glucose. We show that this synthetic pathway can be insulated through the deletion of competing reactions, rational engineering of protein interaction surfaces, direct protein fusion of interacting partners, and co-localization of pathway components on heterologous protein scaffolds.ConclusionsThrough the construction and characterization of a synthetic metabolic circuit in vivo, we demonstrate a novel system that allows for predictable engineering of an insulated electron transfer pathway. The development of this system demonstrates working principles for the optimization of engineered pathways for alternative energy production, as well as for understanding how electron transfer between proteins is controlled.

Novel Low Band Gap Small Molecule and Phenylenevinylene Copolymer with Cyanovinylene 4-Nitrophenyl Segments: Synthesis and Application for Efficient Bulk Heterojunction Solar Cells

A novel star-shaped small monomer SM containing a 1,3,5-triazine core and arms with terminal cyanovinylene 4-nitrophenyls was synthesized. Moreover, an alternating p-phenylenevinylene copolymer P containing thiophene with cyanovinylene 4-nitrophenyl side segments was synthesized by Heck coupling. Both SM and P showed broad absorption spectra with long-wavelength maximum at 630−648 nm, which for P is attributable to an intramolecular charge transfer. The optical band gap was 1.57 eV for SM and 1.70 eV for P. Both SM and P were blended with PCBM to study the donor−acceptor interactions on the blend film morphology and device characteristics of organic bulk heterojunction solar cells. A combination of characterization techniques including X-ray diffraction and optical topographical images were used to investigate the film morphology. The HOMO and LUMO levels of both SM and P are well-aligned with those of the PCBM acceptor, allowing efficient electron transfer and suitable open circuit voltage, leading to overall power conversion efficiencies (PCEs) of 2.53 and 1.43% for SM:PCBM and P:PCBM-based devices, respectively. The thermal annealing leads to suitable phase separation due to the increase in crystallinity of donor material and material distribution so that highly effective bulk heterojunction morphologies are obtained which further increases the PCE up to 3.82% and 2.37% for SM:PCBM and P:PCBM-based devices, respectively. These results are preliminary based on the illumination without using a solar simulator.

Experimental Validation of Aluminum Nitride Energy Harvester Model with Power Transfer Circuit

We present an analytical model of a piezoelectric energy harvester and validate its performance to a finite element analysis and measured data. The model comprises a new piezo-beam component, based on Bernouilli Beam theory and standard piezoelectric theory. The model is parametric and simulates the direct and reverse piezoelectric effect, computing charge and displacement in six degrees of freedom. The harvester with load resistor is co-simulated in a single environment of a commercially available circuit simulator. The accuracy of the model is within 2%. We also present three improvements of the power transfer circuit.

Compact non-binary fast adders using single-electron devices

This paper proposes compact adders that are based on non-binary redundant number systems and single-electron (SE) devices. The adders use the number of single electrons to represent discrete multiple-valued logic state and manipulate single electrons to perform arithmetic operations. These adders have fast speed and are referred as fast adders. We develop a family of SE transfer circuits based on MOSFET-based SE turnstile. The fast adder circuit can be easily designed by directly mapping the graphical counter tree diagram (CTD) representation of the addition algorithm to SE devices and circuits. We propose two design approaches to implement fast adders using SE transfer circuits: the threshold approach and the periodic approach. The periodic approach uses the voltage-controlled single-electron transfer characteristics to efficiently achieve periodic arithmetic functions. We use HSPICE simulator to verify fast adders operations. The speeds of the proposed adders are fast. The numbers of transistors of the adders are much smaller than conventional approaches. The power dissipations are much lower than CMOS and multiple-valued current-mode fast adders.

Longitudinally Excited CO2 Laser with Short Laser Pulse like TEA CO2 Laser

We have developed a longitudinally excited CO2 laser with a short laser pulse similar to that of TEA and Q-switched CO2 lasers. A capacitor transfer circuit with a low shunt resistance provided rapid discharge and a sharp spike pulse with a short pulse tail. Specifically, a circuit with a resistance of 10 M Ω provided a spike pulse width of 103.3 ns and a pulse tail length of 61.9 μs, whereas a circuit with a shunt resistance of 100 Ω provided a laser pulse with a spike pulse width of 96.3 ns and a pulse tail length of 17.2 μs. The laser pulses from this longitudinally excited CO2 laser were used for processing a human tooth without carbonization and for glass marking without cracks.

SFQ Pulse Transfer Circuits Using Inductive Coupling for Current Recycling

An increase in bias currents supplied to single-flux-quantum (SFQ) circuits is a rising problem in building large-scale integrated SFQ circuits, because the magnetic fields generated by bias currents and ground return currents affect the circuit operation. Current recycling technique, which can drastically reduce the total bias current of SFQ circuits, is expected to be a very effective solution for large-scale SFQ circuits. To realize the current recycling technique, signal transmission between SFQ logic circuits located on different ground planes is required. Two types of inductively coupled pulse transfer circuits were examined in this study. One is composed of a simple JTL driver and a DC-SQUID receiver whose junctions are slightly under-damped to enhance the magnetic sensitivity of the SQUID. The other circuit is composed of an SFQ driver based on a delay flip-flop (DFF) and a SQUID receiver. The advantage of the DFF-based circuit is that the coupling time between the driver and the receiver can be increased to ensure appropriate switching in the receiver junction. Two types of transfer circuits were implemented using the SRL 2.5 kA/cm2 Nb process and their correct operation was experimentally confirmed. Circuit structures for effective coupling of the SFQ pulse transfer were also investigated. It was shown that a ground plane boundary should be separated from a ground plane hole underneath coupling inductors to obtain high coupling factors.

On-Chip Measurement of Jitter Transfer and Supply Sensitivity of PLL/DLLs

This brief describes low-cost on-chip measurement circuits for jitter transfer and supply sensitivity of phase-locked loops (PLLs) and delay-locked loops (DLLs). Unlike previous works that measured the frequency-domain responses, the proposed circuits measure the time-domain responses of the PLL/DLL to the periodic disturbances applied to either its input clock phase or its supply voltage. A synchronous sampling technique accurately measures the PLL/DLL's periodic response while suppressing the unrelated noises and interferences via averaging. The synchronous sampler outputs either DC voltage or digital values, making it suitable for low-cost characterization and production tests. The procedure for estimating the frequency-domain transfer functions from the measured time-domain responses is outlined. The jitter transfer and supply sensitivity measurements were demonstrated with a PLL fabricated in 0.13-mum CMOS. Compared with the PLL that occupied 1.1x0.46 mm2 and dissipated 36 mW from a 1.2-V supply, the on-chip measurement circuits occupied only 0.014 mm2 and dissipated only 2.6 mW.