Logic Scheme Research Articles

Time-of-Flight PET Detector Based on Multi-Pixel Photon Counter and Its Challenges

Geiger-mode multi-pixel APD is being recognized as the best alternative solid-state photo-sensor to vacuum PMT for various specific applications. Especially, its magnetic field immunity and high gain made it popular in MR/PET detector research. In this paper, we utilized its compactness, high gain and high photon detection efficiency in the design of TOF PET detector. In a typical block detector based on PMT, the full timing capability of both PMT and scintillator could not be achieved due to its light sharing for Anger logic scheme. Since Geiger-mode APD is a solid-state based technology, we can apply one-to-one coupling between a scintillator and the photo-sensor to optimize the signal-to-noise ratio. Also, the high photon detection efficiency of MPPC, Geiger mode APD from Hamamatsu, would help to improve timing resolution. So, we made a block detector based on a 4 × 4 array of 3 × 3 mm2 MPPC coupled to a 4 × 4 array of 3 × 3 × 25 mm3 LYSO crystals to evaluate its performance. We have achieved the average of 9% energy resolution and 314 ps coincidence timing resolution with very good uniformity. This block timing resolution showed no degradation in timing compared to individual single channel timing resolution as expected from one-to-one readout. On top of that, the result proves that the solid-state based photo-sensor can be used for TOF PET detector. During the development and setup of the detector, we recognized that a compact and low power electronics readout scheme is one of the biggest challenges, including its cost, for MPPC or other Geiger-mode APD to be used in products.

Sequential logic and random access memory (RAM): a molecular approach

Since it was first suggested that molecules could be used for information processing, there has been a significant effort to generate systems that behave according to various logic schemes. Here we will summarize and discuss various approaches that serve one common goal: constructing a (bio)-molecular flip–flop. This logic circuit is at the core of random access memory (RAM) and is one of the pillars of sequential logic. We will highlight the concept underlying various approaches towards flip–flops and we will discuss how these constitute and expand the field of molecular logic. This multi-disciplinary approach results in various schemes that range from all photonic systems to transition metal complexes and hybrid nanoparticle/protein-based systems on solid supports.

TOWARDS BRAIN-INSPIRED COMPUTING

We present introductory considerations and analysis toward computing applications based on the recently introduced deterministic logic scheme with random spike (pulse) trains [Phys. Lett. A373 (2009) 2338–2342]. Also, in considering the questions, "why random?" and "why pulses?", we show that the random pulse based scheme provides the advantages of realizing multivalued deterministic logic. Pulse trains are realized by an element called orthogonator. We discuss two different types of orthogonators, parallel (intersection-based) and serial (demultiplexer-based) orthogonators. The last one can be slower but it makes sequential logic design straightforward. We propose generating a multidimensional logic hyperspace [Phys. Lett. A373 (2009) 1928–1934] by using the zero-crossing events of uncorrelated Gaussian electrical noises available in the chips. The spike trains in the hyperspace are non-overlapping, and are referred to as neuro-bits. To demonstrate this idea, we generate three-dimensional hyperspace bases using the zero-crossing events of two uncorrelated Gaussian noise sources. In such a scenario, the detection of different hyperspace basis elements may have vastly differing delays. We show that it is possible to provide an identical speed for the detection of all the hyperspace bases elements using correlated noise sources, and demonstrate this for the two neuro-bits situation. The key impact of this paper is to demonstrate that a logic design approach using such neuro-bits can yield a fast, low power and environmental variation tolerant means of designing computer circuitry. It also enables the realization of multivalued logic, and also significantly increasing the complexity of computer circuits by allowing several neuro-bits to be transmitted on a single wire.

INSTANTANEOUS NOISE-BASED LOGIC

We show two universal, Boolean, deterministic logic schemes based on binary noise timefunctions that can be realized without time-averaging units. The first scheme is based on a new bipolar random telegraph wave scheme and the second one makes use of the recent noise-based logic which is conjectured to be the brain's method of logic operations [Phys. Lett. A 373 (2009) 2338–2342]. Error propagation and error removal issues are also addressed.

The Performance of Magnetic Tunnel Junction Integrated on the Back-End Metal Line of Complimentary Metal–Oxide–Semiconductor Circuits

In this paper, we have described the complementary metal–oxide–semiconductor (CMOS)/magnetic tunnel junction (MTJ) integrated process technology; MTJs were fabricated on via metal with surface roughness of 0.3 nm with 0.14 µm CMOS process and 60 ×180 nm2 MTJ process. It is shown that by this process technology, the fabricated MTJ on CMOS logic circuit plane achieves a large change in a resistance of 3.63 kΩ (anti-parallel) with the TMR ratio of 138% at room temperature, which is large enough for a sensing scheme of standard CMOS logic. Furthermore, we have successfully demonstrated the DC and AC operation of this MTJ with write transistors. As the results, our MTJ achieves high enough write/read performance with transistors for realizing MTJ-based logic circuits.

Design for High-Speed Optoelectronic Boolean Logic

We present a method of optoelectronic logic that relies on the digital optical switch. The logic gate is reconfigurable to implement the Boolean operators and, or, and not. Multiple logic gates can be cascaded on a single optoelectronic integrated chip to achieve complex logical functionality. The optoelectronic logic scheme uses a high-speed high-power photodetector, combined with a high-speed traveling-wave modulator. As the system is designed without electronic amplifiers or electronic logic elements, the system bandwidth can exceed 10 GHz.

Logic gates scheme based on Coulomb blockade in metallic nanoclusters with organic ligands

We propose a logic gates scheme based on the electron transfer through metallic nanoclusters linked to organic ligands and discuss theoretically the characteristics needed for practical implementation. As a proof-of-the-concept, we demonstrate the OR, AND and NOT gates and study the performance in terms of temperature, applied voltage, and noise.

Comparative study of variable size perturbation and observation maximum power point trackers for PV systems

Perturbation and observation (P&O) maximum power point tracking (MPPT) algorithms are common in photovoltaic (PV) systems due to its ease of implementation. However, operation with fixed size perturbations results in a trade-off between speed of response and maximum power yield in the steady-state. This paper discusses the use of Fuzzy logic and non-switching zone schemes for implementing variable size perturbations for improved transient and steady-state responses. The potential performance of four different P&O algorithms is investigated by means of simulations. Experimental results are then used to verify how the computational burden of each algorithm and the processing speed of a digital signal processor (DSP) affect the performance of each method in a prototype. The best performance is achieved with a new strategy called non-switching zones in the V PV × I PV plane. The power electronics converter operates with duty cycle ( D) equal to 0 or 1, depending on which non-MPP region the system operates, pushing the operating point the fastest way possible towards the MPP region, for improved transient response. At the MPP region, a reduced Fuzzy P&O MPPT algorithm optimized for small variations around the MPP is used for reduced oscillations and increased power yield in the steady-state.

Prediction of Plantar Shear Stress Distribution by Artificial Intelligence Methods

Shear forces under the human foot are thought to be responsible for various foot pathologies such as diabetic plantar ulcers and athletic blisters. Frictional shear forces might also play a role in the metatarsalgia observed among hallux valgus (HaV) and rheumatoid arthritis (RA) patients. Due to the absence of commercial devices capable of measuring shear stress distribution, a number of linear models were developed. All of these have met with limited success. This study used nonlinear methods, specifically neural network and fuzzy logic schemes, to predict the distribution of plantar shear forces based on vertical loading parameters. In total, 73 subjects were recruited; 17 had diabetic neuropathy, 14 had HaV, 9 had RA, 11 had frequent foot blisters, and 22 were healthy. A feed-forward neural network (NN) and adaptive neurofuzzy inference system (NFIS) were built. These systems were then applied to a custom-built platform, which collected plantar pressure and shear stress data as subjects walked over the device. The inputs to both models were peak pressure, peak pressure-time integral, and time to peak pressure, and the output was peak resultant shear. Root-mean-square error (RMSE) values were calculated to test the models' accuracy. RMSE/actual shear ratio varied between 0.27 and 0.40 for NN predictions. Similarly, NFIS estimations resulted in a 0.28-0.37 ratio for local peak values in all subject groups. On the other hand, error percentages for global peak shear values were found to be in the range 11.4-44.1. These results indicate that there is no direct relationship between pressure and shear magnitudes. Future research should aim to decrease error levels by introducing shear stress dependent variables into the models.

Data Modeling for Tools and Technologies for the Analysis and Synthesis of NANOstructures (TASNANO) Project

The main aim of TASNANO project is to focus on the development of a web-based system that allows cooperative work between partners. Even if some commercial tools become available, the specificities of nanotechnology applications suggest implementing an ad-hoc tool. This approach permits to update information every moment, so that not only the latest versions of the documents are always available, but also the raw experimental data are shared in a protected environment. Organizing big amount of data begins with modeling of conceptual schemes, which individualizes entities involved into the project and links between them. The rules’ application of logic modeling leads to the production of a logic scheme. The model allows the data base design, which can be enlarged and enriched preserving coherence and avoiding redundancy. Data and information can be directly treated on the web in accordance with latest modifications.

Deterministic multivalued logic scheme for information processing and routing in the brain

Driven by analogies with state vectors of quantum informatics and noise-based logic, we propose a general scheme and elements of neural circuitry for processing and addressing information in the brain. Specifically, we consider random (e.g., Poissonian) trains of finite-duration spikes, and, using the idealized concepts of excitatory and inhibitory synapses, offer a procedure for generating 2 N − 1 orthogonal vectors out of N partially overlapping trains (“neuro-bits”). We then show that these vectors can be used to construct 2 2 N − 1 − 1 different superpositions which represent the same number of logic values when carrying or routing information. In quantum informatics the above numbers are the same, however, the present logic scheme is more advantageous because it is deterministic in the sense that the presence of a vector in the spike train is detected by an appropriate coincidence circuit. For this reason it does not require time averaging or repeated measurements of the kind used in standard cross-correlation analysis or in quantum computing.

A software application for possibilistic fuzzy diagnosis in complex system

This paper discusses a knowledge-base encoding methodology for diagnostic tasks. It transform “expert”-provided rules into algebraic expressions so inference of the “possible” disorders is carried out via associated constrained optimisation problems. In this way, the need of conventional fuzzy inference systems or “uncertain”-logic schemes is no longer present in the particular setting in this paper. The problem is solved by efficient linear programming tools, in principle able to cope with large-scale problems. Direct introduction of the inequalities and cost indices is cumbersome and error-prone so a user-friendly front-end has been developed.

Automatic Measurement for Internal Resistance of Battery in Uninterruptible Power Source

Automatic Measurement for Internal Resistance of Battery in Uninterruptible Power SourceThis paper considers the approach to the measurement of internal resistance of the battery in the uninterruptible power sources (UPSs [1]). Advantages of the approach are the measurements in power supplies without switching-off the battery, simplicity in realization of algorithm.The basic expressions of the theory used in the method about internal resistance of the storage battery are considered.The function chart of construction of an analog part of the scheme, and also algorithm of action of the scheme of logic of decision-making are considered.Construction of the tracing generator of load, the important part in realization of the method is stated. The use of the analog machine for processing of the results of measurements and a differential method of measurement with the purpose of increase the accuracy of the method is offered.

Fuzzy tuning PI control for initial levitation of micromachined electrostatically levitated gyroscope

A novel microgyroscope based on UV-LIGA technology is described, in which the wheel-like rotor is levitated and rotated by the electrostatic forces. A simple fuzzy logic scheme for online tuning of PI (proportional integral) controller parameters to improve system robustness of initial levitation is outlined. Experimental results indicate that, with fuzzy tuning, the overshoot is reduced to 17% compared with 27% of the conventional PI controller. The rise time for the two channels of the four is 3.6 ms and the settle time is nearly 25.6 ms, which shows a quick response time and good steady-state performance. From the experiment of 0.5 g pulse acceleration input, sensitivity along axial direction is 1 V/g when it acts as an accelerometer.

Tool wear condition monitoring using a sensor fusion model based on fuzzy inference system

One of the biggest problems in manufacturing is the failure of machine tools due to loss of surface material in cutting operations like drilling and milling. Carrying on the process with a dull tool may damage the workpiece material fabricated. On the other hand, it is unnecessary to change the cutting tool if it is still able to continue cutting operation. Therefore, an effective diagnosis mechanism is necessary for the automation of machining processes so that production loss and downtime can be avoided. This study concerns with the development of a tool wear condition-monitoring technique based on a two-stage fuzzy logic scheme. For this, signals acquired from various sensors were processed to make a decision about the status of the tool. In the first stage of the proposed scheme, statistical parameters derived from thrust force, machine sound (acquired via a very sensitive microphone) and vibration signals were used as inputs to fuzzy process; and the crisp output values of this process were then taken as the input parameters of the second stage. Conclusively, outputs of this stage were taken into a threshold function, the output of which is used to assess the condition of the tool.

Horizon-switching Predictive Set-point Tracking under Input-increment Saturations and Persistent Disturbances

Predictive switching logic schemes are considered whereby a feedback-gain is switched-on at any time from a family of candidate feedback-gains so as to deal with the problem of set-point tracking in Asymptotically Null-controllable with Bounded Input (ANCBI) systems under input-increment saturations and persistent arbitrary bounded disturbances. It is constructively shown that such schemes do exist which ensure, along with good tracking performance, global asymptotic and semi-global exponential stability in the noiseless case, as well as bounded-noise bounded-state l∞-stability, whenever the disturbances enter the system in such a way to make these properties conceptually achievable.

A shot in the dark

Investigations of recent blackouts indicate that the root cause of almost all of these major power system disturbances is voltage collapse rather than the underfrequency conditions prevalent in the blackouts of the 1960s and 1970s. The operation of today's power system with generation frequently being remote from the load centers has made the power system very dependent on the utility transmission system. When transmission lines trip, voltage drops at the load center, whereas frequency may remain normal until a complete system collapse occurs. Utilities have begun to recognize this problem and are installing UVLS programs. Also the industrial customers that have in-house generation that operates in parallel with the utility need to recognize the problem. These industrial cogeneration customers should consider the use of undervoltage separation schemes in addition to their existing underfrequency schemes to address the voltage collapse scenario. This article proposes undervoltage separation logic schemes that can be easily installed within digital relays to enhance the security of an undervoltage separation to prevent false operation due to slow-clearing system faults. The article also indicates the required point of installation of these relays so that they properly measure system voltage.

Logic and Analog Test Schemes for a Single-Chip Pixel-Parallel Fingerprint Identification LSI

This paper describes logic and analog test schemes that improve the testability of a pixel-parallel fingerprint identification circuit. The pixel contains a processing circuit and a capacitive fingerprint sensor circuit. For the logic test, we propose a test method using a pseudo scan circuit to check the processing circuits of all pixels simultaneously. In the analog test, the sensor circuit employs dummy capacitance to mimic the state of a finger touching the chip. This enables an evaluation of the sensitivity of all sensor circuits on logical LSI tester without touching the chip with a finger. To check the effectiveness of the schemes, we applied them to a pixel array in a fingerprint identification LSI. The pseudo scan circuit achieved a 100% failure-detection rate for the processing circuit. The analog test determines that the sensitivities of the sensor circuit in all pixels are in the proper range. The results of the tests confirmed that the proposed schemes can completely detect defects in the circuits. Thus, the schemes will pave the way to logic and analog tests of chips integrating highly functional devices stacked on a LSI.

EEG/MEG Signal Processing

EEG/MEG Signal Processing

SEMI-ACTIVE SUSPENSION CONTROL IN A PASSENGER CAR USING A GA-FUZZY APPROACH

A quarter-car hydraulic semi-active suspension system is designed and built for investigating its dynamic model and control behavior. For improving the dynamic response performance, controllers that use a fuzzy logic scheme and a GA-fuzzy strategy are adopted and compared experimentally. Generally, the fuzzy logic controller (FLC) has a limitation on the best performance it can deliver. Therefore, the authors used a genetic algorithm (GA) to determine the optimal parameters of FLC. The experimental results for the vibration amplitude of the car body clearly indicate that the proposed GA-fuzzy controller can achieve good driving quality. However, the power spectral density (PSD) of the sprung mass acceleration shows that with this scheme, riding comfort is improved only restrictively. Therefore, a efficient method is proposed and simulated.