Synthesis Formulas Research Articles

Low-Pass NGD Digital Circuit Application for Real-Time Greenhouse Temperature Prediction

An original application of low-pass (LP) negative group delay (NGD) digital circuit for real-time prediction of greenhouse temperature is investigated. Synthesis formulas allowing to determine the LP-NGD parameters in function of the targeted time-advance are established. The characterization technique of LP-NGD digital circuit implemented on microcontroller platform is validated with a deterministic analytical and real temperature slow pulse signals presenting several hour time-duration. The real-time temperature prediction is tested by employing a commercial temperature sensor in the greenhouse environment. As expected, very good prediction of greenhouse temperature is observed. The experimental result demonstrates an outstanding prediction of ambient temperature variation with -30 minutes time-advance during more than fifty-hour or more than two-day real-time sensing. The present research result opens an innovative roadmap for the future smart buildings and industries where the temperature control and monitoring are particularly key challenging tasks.

Interdigital Resonators in Wideband Ridged-Waveguide Filters

Abstract. An interdigital resonator approach for wideband filter applications in ridged-waveguide technology is presented. The interdigital arrangement of the ridged-waveguide resonators ensures stronger coupling between the resonators. As the coupling sections are consequently enlarged by the interdigital arrangement of the resonators, more feasible filter structures are possible at increasing frequencies. The approach itself can be easily implemented with conventional filter synthesis formulas, which is demonstrated by two 20 GHz examples with a bandwidth of 2 GHz and 100 MHz, respectively. The designed filters are subsequently compared to the standard implementation of ridged-waveguide filters.

An Updated Evaluation of Intrathecal IgG Synthesis Markers in Relation to Oligoclonal Bands.

The aim was to evaluate the performance of the latest quantitative marker for intrathecal IgG synthesis and to compare it with other established markers used for the same purpose. We retrospectively applied Auer's and Reiber's intrathecal IgG synthesis formulae in a cohort of 372 patients under investigation for central nervous system demyelination who had undergone lumbar puncture and oligoclonal bands (OCBs) detection for demonstrating intrathecal IgG synthesis. A ROC analysis revealed Auer's formula had lower sensitivity (68%) compared to Reiber's formula (83%) and IgG index (89%), in our cohort of patients that exhibited normal to mildly elevated albumin quotients (4.48 ± 3.93). By excluding possible sources of errors, we assume that Auer's formula is less sensitive than other established tools for the "prediction" of the detection of OCBs in routine cerebrospinal fluid (CSF) analyses due to the mathematical model used. Given the ability of Reiber's hyperbolic formula to describe the blood-CSF IgG distribution across a wide range of blood-brain barrier functionality, its use and the use of similar formulae are recommended for the discrimination between CNS-derived and blood-derived molecules in clinical laboratories.

(+)-Magnolin Enhances Melanogenesis in Melanoma Cells and Three-Dimensional Human Skin Equivalent; Involvement of PKA and p38 MAPK Signaling Pathways.

Magnoliae Flos is a traditional herbal medicine used to treat nasal congestion associated with headache, empyema, and allergic rhinitis. In our preliminary screening of crude drugs used in Japanese Kampo formulas for melanin synthesis, the methanol extract of Magnoliae Flos was found to exhibit strong melanin synthesis activity. However, there have been no studies evaluating the effects of Magnoliae Flos or its constituents on melanogenesis. The present study aimed to isolate the active compounds from Magnoliae Flos that activate melanin synthesis in melanoma cells and three-dimensional human skin equivalent, and to investigate the molecular mechanism underlying melanin induction. The methanol extract of Magnoliae Flos induced an increase of melanin content in both B16-F1 and HMV-II cells. A comparison of melanin induction by three fractions prepared from the extract showed that the ethyl acetate fraction markedly induced melanin synthesis. Bioassay-guided separation of the ethyl acetate fraction resulted in the isolation of seven lignans (1: - 7: ). Among them, (+)-magnolin (5: ) strongly induced melanin synthesis and intracellular tyrosinase activity. Furthermore, the ethyl acetate fraction and 5: clearly induced melanin content in a three-dimensional human skin equivalent. Molecular analysis revealed that 5: triggered the protein expression of tyrosinase, tyrosinase-related protein-1, and tyrosinase-related protein-2. Further analysis of transcriptional factors and signaling pathways demonstrated that 5: induces the protein expression of tyrosinase, tyrosinase-related protein-1, and tyrosinase-related protein-2 activated by the protein kinase A- and p38 mitogen-activated protein kinase-dependent pathways, leading to cAMP-responsive element-binding protein phosphorylation and microphthalmia-associated transcription factor expression. These findings demonstrate the potential of 5: as a potent therapeutic agent for hypopigmentation.

Theory and Original Design of Resistive-Inductive Network High-Pass Negative Group Delay Integrated Circuit in 130-nm CMOS Technology

This paper develops an original design method of high-pass (HP) negative group delay (NGD) integrated circuit (IC). The considered HP-NGD IC is based on a passive topology which is essentially composed of resistor-inductor (RL) network. The paper presents the first time that an unfamiliar HP-topology is designed in miniaturized circuit implemented in 130-nm CMOS technology. The theory of unfamiliar HP-NGD topology based on the voltage transfer function (VTF) analysis is elaborated. The design equations with synthesis formulas of the resistor and inductor are established. The HP-NGD IC CMOS design methodology is introduced. The feasibility of the miniature NGD IC implementation is approved by design rule check (DRC) and layout versus schematic (LVS) approaches. The HP-NGD passive IC is designed in 130-nm CMOS technology. The HP-NGD topology is constituted by RL-network based on CMOS high Ohmic unsalicided N + poly resistor and symmetrical high current spiral inductor. Then, the schematic and layout simulations are presented. The validity of the 130-nm CMOS HP-NGD design is verified by the investigation of 225 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}\,\,\times215\,\,\mu \text{m}$ </tex-math></inline-formula> chip two different miniature circuit proofs-of-concept (POC). The HP-NGD behavior is validated by comparison between the calculated, and schematic and post-layout simulations of the HP-NGD POCs carried out by a commercial tool. As expected, the group delay and VTF magnitude diagrams are in very good correlation. HP-NGD optimal value, NGD cut-off frequency and attenuation, of about (−31 ps, 141 MHz, −3 dB) and (−47 ps, 204 MHz, −5 dB) are obtained from the miniature POCs.

A unified synthesis method for timing-path generation of planar four-bar linkages

The exact and approximate path synthesis problems require different synthesis methods, and mastering multiple design methods increases the engineers’ burden. A unified drawing method can solve the synthesis problem of four and five positions in the existed studies. In this article, a novel unified synthesis method is proposed for the exact and approximate timing-path synthesis. The approximate timing-path synthesis problem is recombining into many groups of the exact timing-path synthesis. The exact timing-path synthesis formulas are derived based on the classical dyad method, while the simplified synthesis formulas are obtained by the linear elimination method with a specific order of elimination. A distance error formula is proposed to find the optimal group from all groups of solutions, where each group of solutions is the possible solution of the pre-recombination synthesis problem. Exact timing-path synthesis usually obtains several groups (12 or 2 groups, theoretically may be 0) of solutions with different kinematic properties, then the error formula is used to find the group of solutions that has the smallest rounding error. Finally, three cases test the proposed method and prove the effectiveness of the method in solving the timing-path synthesis problem by comparing the errors with the literature results.

IgG intrathecal synthesis in HIV-associated neurocognitive disorder (HAND) according to the HIV-1 subtypes and pattern of HIV RNA in CNS and plasma compartments

We hypothesized that humoral immunity stimulation in the CNS in HIV-1C patients would be lower than that in HIV-1B due to a defective Tat chemokine dimotif (C30C31) that might influence cellular trafficking and CNS inflammation. Sixty-eight paired CSF and blood samples from people with HIV (PWH), free of CNS opportunistic infections, were included, HIV-1B (n = 27), HIV-1C (n = 26), and HIV negative (n = 25). IgG intrathecal synthesis was assayed using quantitative and qualitative methods. IgG oligoclonal bands (OCB) in CSF were observed in 51% of PWH, comparable between HIV-1B and HIV-1C, as well as the medians of IgG intrathecal synthesis formulas. The group with HIV infection aviremic in CSF and blood showed 75% of OCB. There was a poor positive correlation between the IgG quotient and GDS. The impact of HIV-1 on IgG intrathecal production was not subtype dependent. Low-grade CNS intrathecal IgG production persists in HIV CNS infection even in PWH with CSF and blood HIV RNA controlled.

Cerebrospinal fluid oligoclonal IgM test in routine practice: Comparison with quantitative assessment of intrathecal IgM synthesis

BackgroundIntrathecal IgM synthesis demonstrated either as cerebrospinal fluid (CSF)-restricted oligoclonal (o-) IgM bands or calculated using various formulas has been linked to more aggressive multiple sclerosis (MS) course. However, the proportion of MS patients showing intrathecal IgM synthesis varies largely between studies. We aimed to explore the relation between different formulas and results of o-IgM, and to assess the frequency of o-IgM bands in an unselected series of samples. Methods432 samples were analyzed for o-IgM, o-IgG and quantitative measures of IgM and IgG synthesis. IgM index and formulas of Reiber, Auer and Öhman were compared to the result of the o-IgM test. ResultsAt the cut-off commonly used, the non-linear formulas for intrathecal synthesis were specific (>94%) but rather insensitive (<40% even at a cut-off of 4 CSF-restricted bands) compared to o-IgM. No significant difference was noted in the performance of different formulas. At a cut-off of 4 bands, 61% of MS patients, but none of the controls were positive for o-IgM. ConclusionsFormulas for intrathecal IgM synthesis are insensitive compared to o-IgM. We propose to evaluate samples with 2 or 3 extra-CSF IgM bands as borderline and only samples with 4 or more as definitely positive.

Analytical Solving the Optimal Control Problem of Spacecraft’s Slew Maneuver with Minimal Energy of Rotation

Dynamic problem of optimal reorientation from an arbitrary initial attitude into the given final angular position with restricted control which minimizes kinetic energy of spacecraft rotation was solved. Termination time of maneuver is known. Quadratic criterion of quality is applied for finding the optimal control program. Use of integral index in special form concerning angular velocity has helped solve the formulated problem by analytical way. Control law was written down in explicit form. Designing the optimal control is based on quaternion variables and models. It is shown that during optimal turn, the controlling moment is parallel to the straight line which is immobile in the inertial space, and direction of spacecraft’s angular momentum in the process of rotation is constant relative to the inertial coordinate system. Special control regime was studied in detail, and conditions of the impossibility of occurrence of this regime are formulated. It is proven that spacecraft rotates by inertia in special control regime if it exists. The formalized equations and computational expressions for determining the optimal rotation program and duration of acceleration and braking were written. A dependence of control variables on phase coordinates is presented also. The proposed control algorithm allows the spacecraft’s reorientation to be carried out within the fixed time period with minimal angular kinetic energy. Analytical expressions for computing the time characteristics of reorientation maneuver are given, and condition for determination of the moment of the beginning of the braking, based on factual kinematic parameters of motion judging by principles of terminal control is formulated, that provides high accuracy of orientation. A comprehensive solution to the control problem is presented for a dynamically symmetric spacecraft: the dependences as explicit functions of time for the control variables are obtained, and relations for calculating the key parameters of the turn maneuver’s control law are given also. A numerical example and the results of mathematical simulation of spacecraft’s motion with optimal control are presented, which demonstrate the practical feasibility of the designed method for controlling the spacecraft attitude. Presence of ready formulas for synthesis of optimal motion program during reorientation maneuver does the executed research as practically significant and suitable for direct use in practice of space flights.

Schiffman Phase Shifters With Wide Phase Shift Range Under Operation of First and Second Phase Periods in a Coupled Line

In this article, a class of improved Schiffman phase shifters with two C-section coupled lines separately operating in the first and second phase periods is presented and analyzed. Theoretical model and closed-form synthesis formulae are utilized to analyze the phase performances of the proposed phase shifters, which reveals significant differences compared to the phase shifters solely operating in the first or second phase period. Compared to the traditional counterparts, the proposed phase shifters can achieve a larger phase shift value and a wider phase shift range at the same impedance ratio. Moreover, under the same impedance ratio, the phase shifter can obtain wider phase shift bandwidth. These features are believed to be very useful in the limitedly realizable coupling strength for a wide phase shift range case. Finally, two sets of comparative experiments, including the operations in the first phase period, second phase period, and the proposed type, are designed and fabricated to validate the proposed approach. The simulated and measured results agree well with the theory and achieve a 33.6% (36.7%) increase in phase shift bandwidth when the phase shift value is 90° (150°) under the impedance ratio of 1.5822 (2.0312).

Autocorrelation-Driven Synthesis of Antenna Arrays—The Case of DS-Based Planar Isophoric Thinned Arrays

A new methodology for the design of isophoric thinned arrays with a priori controlled pattern features is introduced. A fully analytical and general (i.e., valid for any lattice and set of weights) relationship between the autocorrelation of the array excitations and the power pattern samples is first derived. Binary 2-D sequences with known autocorrelation properties, namely the difference sets (DSs), are then chosen as a representative benchmark to prove that it is possible to deduce closed-form synthesis formulas that a priori guarantee to fit requirements on the sidelobe level (SLL), the directivity, the half-power beamwidth, and the power pattern in user-defined directions. The selected results from a wide numerical assessment, which also includes full-wave simulations with realistic radiators, are illustrated to validate the reliability and the accuracy of the proposed design equations and the associated performance bounds.

Time-Domain Experimentation of NGD ActiveRC-Network Cell

A theoretical and experimental investigation of low-pass negative group delay (NGD) topology is introduced. The NGD topology is composed of a low noise amplifier (LNA) and RC-parallel series mounted lumped network. The NGD cell theoretical characterization is elaborated. The NGD properties as NGD level, cut-off frequencies and central frequency are established. The synthesis formulas as function of the expected NGD level and gain are established. The NGD proof of concept using monolithic LNA LEE-9+ manufactured by mini-circuits are designed, simulated, fabricated, and measured. The simulated and measured frequency domain results are in good agreement with the circuit theory. As expected, low-pass NGD behavior is observed with −5 ns-NGD level over 32-MHz bandwidth. The low-pass NGD function meaning is illustrated by the advance of the output pulse signal leading and trailing edges compared to the input ones.

Vector Control for an AC Drive with a Multilevel Frequency Converter Based on an Н-Bridge

Using multilevel topologies for a stand-alone inverter, which is a part of induction or synchronous ac drives, makes it possible to achieve their operation under some fault conditions related to, for example, the failure of any element in a power circuit or short-term blackout in operation of distribution line of centralized power supply system. In the last case, due to switching the speed loop into the mode of voltage control of capacitor filters, it turns out during short-term interval to maintain at the set level the magnetic condition and mechanical coordinates of electrical machine without direct disconnection of converter by corresponding signal feeding from a security unit. The work considers the design formulas for synthesis of special algorithms of vector control by an ac actuating motor under the absence of power supply based on the set distribution of the roots of characteristic polynomial on the complex plane. As well as the reduction of logarithmic amplitude–phase–frequency characteristic of the loop in open condition to the normalized form is presented in the work. Within the framework of these formulas, the regeneration of electric energy in the stand-alone inverter with series-connected H-bridges is carried out to stabilizing the voltage of capacitor bank in each power module owing to when workability recovery of three-phase network, the ac drive returns to normal operation without significant degradation of quality of processes by rotor rotational speed.

Novel synthesis formulas to design square patch frequency selective surface absorber based on equivalent circuit model

A new procedure is presented to design electromagnetic absorbers based on resistive square patch frequency selective surface (FSS) over grounded dielectric. The periodicity (p) and the distance between two adjacent squares in the lattice (w) are two unknowns to be solved, given the thickness and permittivity of the substrate, surface impedance of the square patches and the desired reflectivity in some specified frequency. Equivalent circuit model and transmission line method are employed here. Previously reported analysis formulas to calculate the square patch FSS admittance are exploited and novel synthesis formulas are extracted based of them. The final synthesis equations to calculate p and w are presented in term of polynomials. Usually an absorber is supposed to have a maximum reflectivity r in a frequency band [f1, f2]. The (p, w) pairs for reflectivity less than r in f1, define an area in p-w plane. The intersection of the so-called area with the similar one defined by f2 specifies all possible (p, w) pairs. Finally the results are tested and verified by the commercial full wave simulator Ansys-HFSS as well as some experimental design. There is a good agreement between the expected results with the full wave analysis and practical test.

Canonical transfer function of band‐pass NGD circuit

This study introduces the generalised canonical transfer function (TF) of the band-pass negative group delay (NGD) circuit. The principle to identify the unfamiliar band-pass NGD circuits is suggested. Similar to the filter theory, the band-pass NGD TF can be established from low-pass to band-pass frequency transform. The fundamental characteristics of the NGD topology are described. The canonical TF feasibility is concretised with the second-order equivalent impedance constituted by passive elements. The synthesis formulas in function of the desired NGD level and bandwidth are analytically established. Application examples of band-pass NGD impedance synthesis, designed and fabricated are proposed as a proof of concept. Prototypes of band-pass NGD circuits with centre frequencies 1 and 1.5 MHz for the targeted group delay optimal values, respectively, −1 and −1.5 µs are designed and fabricated. As expected, band-pass NGD results in good agreement with the theoretical prediction were obtained with simple lumped circuits. In the future, thanks to theory simplicity, the NGD band-pass cell can be potentially useful for the signal delay correction.

Design and Analysis of Schiffman Phase Shifter Under Operation of its Second Phase Period

In this paper, a new design concept of Schiffman phase shifters under the operation of the second phase period in frequency domain is presented and analyzed. By investigating phase properties of the C-section structure, we first find that its second phase period is another independent and distinctive working region for Schiffman phase shifter, in addition to its first phase period. In contrast to traditional counterparts working on the first phase period, which are suitable for small phase shift from 0° to 90°, the Schiffman phase shifters on the second phase period are suitable for the large phase shift from 90° to 180°. It is because of the opposite phase variation property that the electrical length of reference line gets shortened as the phase shift value increases. Compared with the first phase period, the second phase period can achieve wider phase shift bandwidth under the same coupling degree. This feature is believed to be very useful in the limited realizable coupling degree cases. In this context, the closed-form synthesis formulas of Schiffman phase shifter on the second phase period are presented. Meanwhile, detail theoretical analysis of the phase shift bandwidth and phase deviation is carried out. In final, two Schiffman phase shifters on the first and second phase periods are designed and fabricated to validate our proposed concept and approach in the experiment.

Analysis and Design of a GaAs Monolithic Tunable Polyphase Filter in S/C Bands

This paper proposes a new topology of a 2-Stages Active Polyphase Filter (APPF) in MMIC GaAs technology. This new topology, named “radial”, allows a greater balancing of output signals phases and amplitudes, over the actual APPF’s at the state of the art. In this paper an ex-novo study is shown and synthesis formulas for the APPF are provided. The MMIC simulations in 1-5GHz bandwidth show a tunable Image Rejection Ratio (IRR) greater than 40dB, a worst case input/output matching of 7.8dB and a maximum insertion loss of 10.8dB. By comparison with the tandem topology, as will be shown in the following, the radial one allows a significant improvement in the electrical performances.

S-transform with maximum energy concentration: Application to non-stationary seismic deconvolution

The S-transform is known as an efficient method for analyzing seismic signals in the time–frequency (TF) domain. However, it provides a TF map with high energy diffusion due to inflexibility of the window function used in its analysis or synthesis formulas. In this paper, an optimization algorithm for S-transform is proposed to find the optimum Gaussian windows for providing a TF map with maximum energy concentration. Afterwards, we show the possibility of obtaining the desired TF map from two different perspectives: generating the TF map from a time-windowed signal or from a frequency-windowed signal. Through the optimization algorithm and by using an energy concentration measure (ECM), the optimum windows are selected instantaneously, for each time or frequency sample. Testing the proposed method on variety of signals shows its good performance to provide a well concentrated TF map, compared with other TF analysis methods. Application of the proposed method to perform non-stationary deconvolution of synthetic and field seismic data sets presents a better performance than short-time Fourier transform (STFT) and standard S-transform (SST) in improving the temporal resolution of the data.

An improved two-stage image registration algorithm for super-resolution

This paper presents an improved two-stage image registration algorithm for super-resolution. The algorithm is based on the rotation–translation (RT) model and the coarse-to-fine strategy. It first uses the phase correlation algorithm to estimate large-scale displacements with pixel-level accuracy after image motion compensation, and then uses the Keren algorithm to obtain high-accuracy sub-pixel estimation. Moreover, from the non-commutative property between rotation and translation in the RT model, synthesis formulae are derived and used to combine the two results together, which could further improve the accuracy without extra computational costs. The algorithm can achieve high-accuracy sub-pixel registration for large-scale displacements, which also has the advantage of good computational efficiency. To illustrate the effectiveness of the algorithm, both simulations and practical super-resolution reconstruction experiments are performed. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Явные формулы синтеза регулятора и наблюдателя для дескрипторной системы

Явные формулы синтеза регулятора и наблюдателя для дескрипторной системы