Open-loop Structure Research Articles

A Demodulation-Based Technique for Robust Estimation of Single-Phase Grid Voltage Fundamental Parameters

This paper proposes a robust technique for the single-phase grid voltage fundamental amplitude, frequency, and phase angle estimation under distorted grid conditions. It is based on a demodulation method tuned at a fixed frequency. It does not have stability issue due to an open-loop structure, does not require real-time evaluation of trigonometric and inverse trigonometric functions, and also avoids the use of look-up table. It can provide accurate estimation of the single-phase grid voltage fundamental parameters under dc offset and harmonics. When compared with a frequency adaptive demodulation technique, the proposed one is less affected by dc offset, can provide faster frequency estimation, and also avoids interdependent loop, trigonometric, and inverse trigonometric functions operation. Simulation and experimental results are presented to verify the performance of the proposed technique.

Detection of Grid Voltage Fundamental and Harmonic Components Using Kalman Filter and Generalized Averaging Method

The proper operation of single-phase and three-phase grid-connected power converters depends on the synchronization with utility networks. The major challenge of the synchronization is how to quickly and precisely extract the ac signal and fundamental positive sequence in single- and three-phase power systems, respectively. This paper proposes a new detection technique based on a modified Kalman filter and the generalized averaging method. The method has an open-loop structure, and uses the orthogonal signals which are obtained directly from the Kalman filter. The resulted detection system is very simple and robust even in the presence of power quality disturbances, such as voltage imbalance, harmonics, and voltage fluctuations. The proposed technique can detect the fundamental and harmonics frequencies within or less than half a cycle in all situations, such as small and considerable frequency variations. Meanwhile, the method guarantees the zero steady-state error in complicated harmonic scenarios, including all typical single-phase and three-phase harmonics. Various case studies are assessed and the performance of the proposed detection method is verified by experiments.

Derivation and Comparison of Open-loop and Closed-loop Neural Network Battery State-of-Charge Estimators

Abstract This paper presents two artificial neural network (ANN) based algorithms for battery state-of-charge (SOC) estimation. The SOC is an important quantity that must be estimated in real-time in many applications. ANN is a mathematical model that consists of interconnected artificial neurons inspired by biological neural networks and is used to predict the output of a dynamic system based on some historical data of that system. The first algorithm presented in this paper has an open-loop structure and known as nonlinear input output (NIO) feed-forward algorithm, while the second is closed loop called nonlinear autoregressive with exogenous input (NARX) feed-back algorithm. A pulse-discharge test is performed on a commercial lithium-ion (Li-ion) battery cell in order to collect data to evaluate those methods. Results are presented and compared.

Improved performance of the micro planar double-axis fluxgate sensors with different magnetic core materials and structures

As a classic weak magnetic field sensor, the fluxgate sensors have great potential application in many fields. This paper presents four kinds of the micro planar double-axis fluxgate sensors based on the MEMS technologies, which have different core materials and core structures. The core materials include electroplated permalloy, Co-based amorphous ribbon and Fe-based amorphous ribbon, and the core structures include single-layer open magnetic loop structure and double-layer closed magnetic loop structure. The sensor with closed double-layer Fe-based ribbon core exhibits a best sensitivity of 238 V/T due to reducing the magnetic flux leakage. The results show that the magnetic core with closed magnetic loop, high permeability and high saturation induction density will help increase the sensitivity of the micro double-axis fluxgate sensor.

A 42 fJ/Step-FoM Two-Step VCO-Based Delta-Sigma ADC in 40 nm CMOS

A 40 MHz-BW 10 bit two-step VCO-based Delta-Sigma ADC is presented. With the open-loop structure and highly digital building blocks, a robust performance, high bandwidth and high power efficiency are achieved. The nonlinearities of the coarse and the fine VCO-based quantizers are mitigated by distortion cancellation and voltage swing reduction schemes respectively. Because of the intrinsic DEM of the VCO-based quantizer output, the matching requirement of the DAC cells is greatly relaxed. The experimental results in 40 nm CMOS show that, with 1.6 GHz sampling frequency, the proposed ADC reaches 59.5 dB SNDR and 67.7 dB SFDR for 40 MHz bandwidth. The power consumption is only 2.57 mW under 0.9 V power supply, corresponding the best FoM (42 fJ/step) among high bandwidth ( 20 MHz) DS ADCs.

Economic Growth and Choice of Energy: A Simplistic Strategic Approach

In this paper, we present a simplistic dynamic model to analyze the tradeoff between the use of environment-friendly energy and the use of environment-polluting energy in a dynamic world characterized by players that have different interests. Our approach builds upon a neoclassical growth model, integrating different economies, and including pollution as a separate growth factor. The model is cast in a differential game framework with the open-loop information structure. In this setting, we analyze the impact of pollution over time on the fossil fuel/“green” energy ratio. Furthermore, based on a simulation study for the linearized model, we consider the question whether certain cooperative arrangements between countries having different interests can be expected in case pollution shocks occur.

Implementation lessons and pitfalls for real‐time optimal control with stochastic systems

Summary Modern computational power and efficient direct collocation techniques are decreasing the solution time required for the optimal control problem, making real-time optimal control (RTOC) feasible for modern systems. Current trends in the literature indicate that many authors are applying RTOC with a recursive open-loop structure, relying on a high recursion rate for implicit state feedback to counter disturbances and other unmodeled effects without explicit closed-loop control. The limitations of using rapid, instantaneous optimal solutions are demonstrated analytically and through application to a surface-to-air missile avoidance control system. Two methods are proposed for control structure implementation when using RTOC to take advantage of error integration through either classical feedback or disturbance estimation. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.

A centralized open loop structure under the Reverse Flow of Material with permissible delay in payment

Reverse logistics systems have become increasingly popular over the last decade in the business and academic community. Firms incorporate reverse flow to their systems for such reasons as ecological and economic factors, government regulations and social responsibilities. Reverse logistics manage the flow of returned used products for remanufacturing or repairing or other purposes. We developed a centralized open loop supply chain inventory model under the situation in which the supplier provides the retailer with a permissible delay of payments. The supplier offers different discount rates of price at different delay periods.Demand is taken to be price and stock dependent. As a result, in this article, we establish a mathematical model to determine the optimal inventory policies. Illustrative examples, which explain the application of the theoretical results, are given. Numerical and the sensitivity analysis are also reported.

Structural significance of modified nucleosides k2C and t6A present in the anticodon loop of tRNAIle

The structural significance of the hypermodified nucleosides lysidine (k2C) and N6-(N-threonylcarbonyl) adenosine (t6A) present in the anticodon loop of E. coli tRNAIle has not been studied in detail theoretically at the atomic level. Hence, in the present paper, we investigated the conformational preferences of modified nucleosides k2C and t6A in the anticodon loop of tRNAIle using various quantum chemical methods. Multiple molecular dynamics simulation studies of the anticodon stem loop (ASL) of tRNAIle have also been made to see the solvation effect. The lysine moiety of lysidine orients back and forms a hydrogen bond with the 2′-hydroxyl group of the 34th ribose sugar whereas the t6A(37) side chain prefers a ‘distal’ conformation. This kind of conformation would be useful for recognition of the codons AUA instead of AUG. The t6A side chain prohibits canonical base pairing and maintains an anticodon open loop structure. The preferred conformations of k2C(34) and t6A(37) are stabilized by various intra as well as inter residual interactions within the anticodon loop which could be useful for maintaining a proper anticodon loop structure for smooth and in phase codon–anticodon interactions during the biosynthesis of proteins.

A new high-speed, high-resolution open-loop CMOS sample and hold

A new open loop, high resolution CMOS sample and hold (S/H) circuit is introduced in this article. This circuit is constructed based on a new method which leads to a great reduction in dependency of the storing charge of the holding capacitors to the charge injection of transistors. It is a combination of dummy switches and auxiliary capacitors in order to decrease the voltage spikes that are produced during the sampling mode. Due to the high linearity feature of our proposed design in comparison with previous works, it is reached to a great improvement in signal to noise and distortion ratio up to about 15 dB and it's ENOB is equivalent with about 16 bits. Another advantages of our proposed design are it's lower power dissipation and it's high input voltage range. Also the optimum functionality of our proposed circuit does not damaged by the threshold voltage's variations in different corners. As our proposed S/H circuit has been designed in open loop structure, it is suitable for high speed applications.

하수슬러지 건조를 위한 폐루프 공기건조 기술에 관한 연구

Air drying is a technology to dry sludge at the ejector and multi cyclone as intaking and blowing air from outside. So, this technology has a weak point that operating fluctuation is large according to an outside conditions as well as energy consumption is also large due to open loop structure. This is to develop the closed-loop air drying system to be built the dehumidifier consisted of condenser, cooler and compressor at rear side of separator of air dryer, as a way to solve some problem. Air is circulation by the method of blowing-drying-dehumidifying-blowing within this system. It is analyzed that an air circulated at closed-loop air drying equipment contains the energy of 50% more compared with open-loop air drying and is operated regularly because of quality maintenance of air to dry sludge. And also it is analyzed that the cost of drying sludge of 1 ton by closed-loop air drying equipment is lower about 35% than conventional equipment. Therefore, this is evaluated by useful drying technology to face an unexpected climatic conditions due to regular operation as well as low energy consumption.

60-GHz AMC-Based Circularly Polarized On-Chip Antenna Using Standard 0.18-$\mu$m CMOS Technology

A 60-GHz artificial magnetic conductor (AMC)-based circularly polarized (CP) on-chip antenna has been designed and fabricated using standard 0.18-μm six metal-layer CMOS technology. The design consists of a wideband circularly polarized loop antenna at the top layer M6 and a novel AMC structure at the bottom layer M1. The size of the antenna including the modified AMC structure is 1.8 × 1.8 × 0.3 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> . The circular open-loop structure is employed for antenna design because the gap within the loop can excite traveling wave current and then achieve circular polarized radiation. In addition, it is found that the bandwidth of circular polarization can be significantly increased by introducing one more inner parasitic loop. With the modified AMC structure integrated into the bottom layer, the antenna performance can be optimized and improved as more design freedom is introduced. The proposed antenna can offer a simulated peak gain of -3.7 dBi and a measured gain of -4.4 dBi, respectively, as well as simulated and measured axial ratio (AR <; 3) bandwidth to cover from 57 to 67 GHz.

New predistorter using triangular memory polynomial for power amplifier of OFDM-based wireless broadband communication system

A triangular memory polynomial (TMP) predistorter is presented in this paper to linearize a power amplifier's nonlinear with memory effects. Compared with the traditional memory polynomial (MP) predistorter, the coefficients of TMP predistorter is reduced more than 75%, which can effectively decrease the implementation complexity. The coefficients of predistorter are directly extracted from an offline system identification process by an open-loop structure in our approach. Several signals with data rate 5 MHz, 10 MHz, 15 MHz and 20 MHz are used to verify the performance of the proposed predistorter. Experimental results show that the proposed TMP predistorter and the traditional MP predistorter almost have the same performance.

Compact Stub-Coupled Square Open-Loop Bandpass Filter for Ku-Band Applications

A typical stub-loaded compact planar microwave square open-loop based bandpass filter (BPF) is proposed in this paper. The internally loaded stubs are open and attached type accommodated inside the square loops. A large coupling coefficient value can be possible in the square open-loop resonator using those loaded stubs. The open loaded-stub is a modified stepped-impedance resonator (SIR) structure, and the attached stubs are two similar and rectangular structures. By integrating the three loaded stubs into the two squareloops using open gaps and employing direct-connected asymmetrical feeders, the combination of such structures excites the resonator filter at 12GHz resonant frequency which is applied to get bandpass filter with wideband passband response with high input reflection coefficient. The proposed open-loop filter structure has strong electric coupling because the open sides of two coupled loop resonators are proximately placed face-to-face in parallel. The internally loaded stubs help to connect magnetic coupling easily. Therefore, the mixed coupling generates strong electromagnetic coupling in the BPF with high input reflection coefficient and broader bandwidth on the required frequency band. The S-parameters responses of the fabricated filter nearly match the electromagnetic simulation results. Therefore, the feasibility of the proposed filter is approved.

MacA is a Second Cytochrome c Peroxidase of Geobacter sulfurreducens

The metal-reducing δ-proteobacterium Geobacter sulfurreducens produces a large number of c-type cytochromes, many of which have been implicated in the transfer of electrons to insoluble metal oxides. Among these, the dihemic MacA was assigned a central role. Here we have produced G. sulfurreducens MacA by recombinant expression in Escherichia coli and have solved its three-dimensional structure in three different oxidation states. Sequence comparisons group MacA into the family of diheme cytochrome c peroxidases, and the protein indeed showed hydrogen peroxide reductase activity with ABTS(-2) as an electron donor. The observed K(M) was 38.5 ± 3.7 μM H(2)O(2) and v(max) was 0.78 ± 0.03 μmol of H(2)O(2)·min(-1)·mg(-1), resulting in a turnover number k(cat) = 0.46 · s(-1). In contrast, no Fe(III) reductase activity was observed. MacA was found to display electrochemical properties similar to other bacterial diheme peroxidases, in addition to the ability to electrochemically mediate electron transfer to the soluble cytochrome PpcA. Differences in activity between CcpA and MacA can be rationalized with structural variations in one of the three loop regions, loop 2, that undergoes conformational changes during reductive activation of the enzyme. This loop is adjacent to the active site heme and forms an open loop structure rather than a more rigid helix as in CcpA. For the activation of the protein, the loop has to displace the distal ligand to the active site heme, H93, in loop 1. A H93G variant showed an unexpected formation of a helix in loop 2 and disorder in loop 1, while a M297H variant that altered the properties of the electron transfer heme abolished reductive activation.

Continuous-Time Non-Symmetric Algebraic Riccati Theory: A Matrix Pencil Approach

A continuous-time non-symmetric algebraic Riccati system which incorporates as a particular case the non-symmetric algebraic Riccati equation is studied under assumptions on the matrix coefficients relaxed as far as possible. Necessary and sufficient existence conditions together with computable formulas for the stabilizing solution are given in terms of proper deflating subspaces of an associated matrix pencil. A numerically-sound algorithm able to decide existence and to compute the stabilizing solutions, if any, to the algebraic Riccati system is recalled. The whole development may be applied to fluid queues, transport theory, and game theory with an open-loop information structure without assuming the classical invertibility hypothesis on the quadratic matrix coefficient.

An efficient algorithm for equations of motion of molecular dynamical systems

This paper presents a new efficient sequential O ( N ) algorithm for computer modelling of the motion behaviours of molecular dynamical systems. The method is based on the frozen lightly-excited degrees of freedom of an atom in a molecular system, such as inter-atomic oscillations and rotation about double bonds with high frequencies, so that a reduced molecular system with rigid subsets and joints is formed. Then Kane’s dynamical equations and the internal coordinate method (ICM) are applied to the reduced model for recursive formation and solution of equations of motion of the atomistic molecular system. The increased computational efficiency is accomplished through three sequential computing sweepings along the structure of the molecular system so that the equations of motion are solved when they are being formed at a fixed computing cost. The algorithm provides a sequential O ( N ) computational performance for a molecular system with an open-loop structure. Here N is the total number of subsets.

Study on the relation of structure and antioxidant activity of isorhamnetin, quercetin, phloretin, silybin and phloretin isonicotinyl hydrazone

Background: Some flavonoids compounds from the Chinese Traditional Medicine such as isorhamnetin, quercetin, phloretin, silybin have excellent antioxidant activity. Phloretin isonicotinyl hydrazone which was a new compound synthesized by our team, was expected to have more antioxidant activity than phloretin. Materials and Methods: The experiment examined the scavening free radicals activity and inhibition of lipid peroxidation activity of quercetin, isorhamnetin, phloretin, silybin and phloretin isonicotinyl hydrazone, with the methods including scavening1,1-diphenyl-2-picrylhydrazyl(DPPH) radical,2,2-azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid (ABTS) radical and inhibition of Sprague Dawley (SD) rats liver mitochondria lipid peroxidation induced by Fe2+ / Vc system in vitro. Results: The experiment results showed that the five flavonoids had excellent antioxidant activity with the suitable concentration. In the experiment of scavening DPPH, ABTS radicals and inhibiting lipid peroxidation, the IC50 of isorhamnetin was respectively 24.61μmol/L,14.54μmol/L, 6.67μmol/L. The IC50 of quercetin was respectively 3.07μmol/L, 3.64μmol/L, 6.67μmol/L. The IC50 of phloretin was respectively 7.69μmol/L, 4.54μmol/L, 12.50μmol/L. The IC50 of phloretin isonicotinyl hydrazone was respectively 1.92 μmol/L, 2.27μmol/L, 2.08μmol/L. The IC50 of silybin was respectively 96.15μmol/L, 7.10μmol/L,104.16μmol/L. Conclusion: The experiment results showed that quercetin, isorhamnetin, phloretin, silybin and phloretin isonicotinyl hydrazone had excellent antioxidant activity. This was the first time to study the antioxidant activity of phloretin isonicotinyl hydrazone. Moreover, for isorhamnetin, quercetin, phloretin, silybin, this was the first time to study the activity of inhibition of SD rats liver mitochondria lipid peroxidation induced by Fe2+ / Vc system in vitro. In a word, the results of experiments showed that the molecular had more phenolic hydroxyl groups, the ability of scavenging DPPH, ABTS radicals free radical was stronger. While phloretin isonicotinyl hydrazone which was added a hydrazone group, increased the ability of scavenging DPPH, ABTS free radical and inhibiting lipid peroxidation than phloretin. Quercetin is the typical structure flavonoid, phloretin is the two-hydrogen-chalcone flavonoid with the open loop structure after hydrogenation. Silybin is the lignan flavonoid compound which has the ABCDE five rings, the structure is much more complicated. The different molecular structures of quercetin , phloretin and silybin lead to the different antioxidant activity.

On designing geometric motion planners to solve regulating and trajectory tracking problems for robotic locomotion systems

Based on a geometric fiber bundle structure, a generalized method to solve both regulation and trajectory tracking problems for locomotion systems is presented. The method is especially applied to two case studies of robotic locomotion systems; a three link articulated fish-like robot as a prototype of locomotion systems with symmetry, and the snakeboard as a prototype of mixed locomotion systems. Our results show that although these motion planners have an open loop structure, due to their generalities, they can steer case studies with negligible errors for almost any complicated path.

A rate-distortion analysis on motion prediction efficiency and mode decision for scalable wavelet video coding

A rate-distortion model for describing the motion prediction efficiency in interframe wavelet video coding is proposed in this paper. Different from the non-scalable video coding, the scalable wavelet video coding needs to operate under multiple bitrate conditions and it has an open-loop structure. The conventional Lagrangian multiplier, which is widely used to solve the rate-distortion optimization problems in video coding, does not fit well into the scalable wavelet structure. In order to find the rate-distortion trade-off due to different bits allocated to motion and textual information, we suggest a motion information gain (MIG) metric to measure the motion prediction efficiency. Based on this metric, a new cost function for mode decision is proposed. Compared with the conventional Lagrangian method, our experiments show that the proposed method is less extraction-bitrate dependent and generally improves both the PSNR performance and the visual quality for the scalability cases.