Fundamental Modulation Research Articles

Modulation of surface properties on cobalt phosphide for high-performance ambient ammonia electrosynthesis

Tuning surface properties of electrocatalysts for sustainable electrocatalytic nitrogen reduction reaction (NRR) with high selectivity and activity is highly demanded but still lacks fundamental understanding and modulation methods. Herein, we report the transformation of hydrogen evolution reaction (HER)-favorable cobalt phosphide (CoP) to NRR-favorable electrocatalyst via modulation of surface properties. The oxidized CoP particles encapsulated in carbon nanotubes (O-CoP/CNT) exhibits a high NH3 yield of 39.58 µg h−1 mg-1 cat as well as high Faradaic efficiency (FE) of 19.4% at −0.5 V vs. reversible hydrogen electrode (RHE), which is confirmed by 15N2 isotope-labeling tests. In-situ Raman spectra identify that N2 molecules are preferentially captured by Co ions, while the surface-adsorbed H+ are gradually eliminated. The hydrophobic surface of CNT can limit the contact of protons with the catalyst surface to inhibit HER, and the formation of hydrogen bond facilitates a more efficient NRR process. The surface modulation effects are confirmed by density functional theory calculations.

Harmonic Suppression Scheme for Multipulse Converter Fed Multilevel Inverter-Based IM Drive

The medium-voltage induction motor drives are regularly utilized for crucial application in enormous industries. It is difficult to design a highly efficient drive system with a satisfactory power quality standard not only at the drive end but also at the grid end. To breakthrough this issue, a 36-pulse ac–dc converter fed seven-level binary cascaded H-bridge multilevel inverter (CHB-MLI) based drive system is presented in this work, where a 36-pulse converter is employed to enhance the power quality at the grid end. For this, the phase-shifted technique is implemented on a multiwinding transformer to eliminate the harmonics injected by the nonlinear diode bridge rectifier toward the grid side. Apart from this, the genetic algorithm selective harmonic elimination (GA-SHE) is applied to a seven-level binary CHB-MLI to diminish lower order (fifth and seventh) harmonics at the drive end. Moreover, a GA is adopted to determine the optimized switching angles by the solution of the nonlinear trigonometric equation of SHE. Furthermore, the GA-SHE-based fundamental frequency modulation scheme is favorable to decrease the switching losses and to enhance the drive end converter efficiency. The performance during the dynamics and steady state of the presented drive system with the indirect field-oriented control is analyzed through simulations and experiments on 298.4 kW and 7.5 kW squirrel-cage induction motors, respectively.

Beyond Massive MIMO: Living at the interface of electromagnetics and information theory

Beyond Massive MIMO: Living at the interface of electromagnetics and information theory Information theory, proposed by Claude Shannon in 1948, has served the wireless communications community particularly well for seven decades. Looking ahead, this theoretical framework needs to be extended to account for the unique electromagnetic properties of concurrent (e.g. 5G) and future (e.g. beyond 5G, 6G) massive multiple-input multiple-output systems. This is a challenging exercise: information theory is based on probabilistic tools whilst electromagnetic theory encompasses Maxwell’s wave equations. BEATRICE aims to use these two theories in parallel to create new fundamental understanding, modulation techniques and physical prototypes. These findings will have a far-reaching impact on cellular communications, wireless power transfer, radar, and optical wireless communications.

A dual-beam lens-free slot-array antenna coupled high-T c superconducting fundamental mixer at the W-band

This paper presents a W-band high-T c superconducting (HTS) Josephson-junction fundamental mixer which is coupled using a dual-beam lens-free slot-array antenna. The antenna features a uniplanar six-element slot array fed by an ungrounded coplanar waveguide line, of which each element is a long slot loaded by four rectangular loops. Highly directional radiation is therefore realized by utilizing the long slots and array synthesis to form a relatively large antenna aperture. The antenna also enables asymmetric dual-beam radiation in opposite directions, which not only reduces the RF coupling losses but greatly facilitates the quasi-optics design for the integration of the HTS mixer into a cryocooler. The electromagnetic simulations show that a coupling efficiency as high as −2.2 dB, a realized gain of 13 dB and a front-to-back ratio of 10 dB are achieved at the frequency of 84 GHz. Using this on-chip antenna, a W-band HTS fundamental mixer module is experimentally developed and characterized for different operating temperatures. The measured conversion gain is −10 dB at 20 K and −14.6 dB at 40 K, respectively. The mixer noise temperature is predicted to be around 780 K at 20 K and 1600 K at 40 K, respectively. It is also analyzed that the mixer performance can be further improved if the Josephson junction parameters were optimized.

The Effects of Remote Signal Transmission and Recording on Acoustical Measures of Simulated Essential Vocal Tremor: Considerations for Remote Treatment Research and Telepractice

PurposeStudies on medical and behavioral interventions for essential vocal tremor (EVT) have shown inconsistent effects on acoustical and perceptual outcome measures across studies and across participants. Remote acoustical and perceptual assessments might facilitate studies with larger samples of participants and repeated measures that could clarify treatment effects and identify optimal treatment candidates. Furthermore, remote acoustical and perceptual assessment might allow clinicians to monitor clients’ treatment responses and optimize treatment approaches during telepractice. Thus, the purpose of this study was to evaluate the accuracy of remote signal transmission and recording for acoustical and perceptual assessment of EVT. MethodSimulations of EVT were produced using a computational model and were recorded using local and remote procedures to represent client- and clinician-end recordings respectively. Acoustical analyses measured the extent and rate of fundamental frequency (fo) and intensity modulation to represent vocal tremor severity and the cepstral peak prominence (CPPS) to represent voice quality. The data were analyzed using repeated measures analysis of variance (ANOVA) with recording as the within-subjects factor and sex of the computational model as the between-subjects factor. ResultsThere was a significant main effect of recording on the rate of fo modulation and significant interactions of recording and sex for the extent of intensity modulation, rate of intensity modulation, and CPPS. Posthoc pairwise comparisons and analysis of effect size indicated that recording procedures had the largest effect on the extent of intensity modulation for male simulations, the rate of intensity modulation for male and female simulations, and the CPPS for male and female simulations. Despite having disabled all known software and computer audio enhancing options and having stable ethernet connections, there was inconsistent attenuation of signal amplitude in remote recordings that was most problematic for samples with a breathy voice quality but also affected samples with typical and pressed voice qualities. ConclusionsAcoustical measures that correlate to perception of vocal tremor and voice quality were altered by remote signal transmission and recording. In particular, signal transmission and recording in Zoom altered time-based estimates of intensity modulation and CPPS with male and female simulations of EVT and magnitude-based estimates of intensity modulation with male simulations of EVT. In contrast, signal transmission and recording in Zoom minimally altered time- and magnitude-based estimates of fo modulation with male and female simulations of EVT. Therefore, acoustical and perceptual assessments of EVT should be performed using audio recordings that are collected locally on the participant- or client-end, particularly when measuring modulation of intensity and CPP or estimating vocal tremor severity and voice quality. Development of procedures for collecting local audio recordings in remote settings may expand data collection for treatment research and enhance telepractice.

Graded quiver varieties and singularities of normalized R-matrices for fundamental modules

We present a simple unified formula expressing the denominators of the normalized R-matrices between the fundamental modules over the quantum loop algebras of type $${\mathsf {ADE} }$$ . It has an interpretation in terms of representations of Dynkin quivers and can be proved in a unified way using geometry of the graded quiver varieties. As a by-product, we obtain a geometric interpretation of Kang–Kashiwara–Kim’s generalized quantum affine Schur–Weyl duality functor when it arises from a family of the fundamental modules. We also study several cases when the graded quiver varieties are isomorphic to unions of the graded nilpotent orbits of type $$\mathsf {A} $$ .

Pre-Weighted Midpoint Algorithm for Efficient Multiple-View Triangulation

Triangulation is a fundamental module in vision based navigation system, which reconstructs the observed 3D point using cameras with known intrinsic and poses. In this article, we adopt the minimization of the angular residual as the criterion of triangulation and a novel structure of multiple-view triangulation is proposed. A multiple-view triangulation problem is divided into several two-view triangulation problems and a linear algorithm is derived to find the explicit closed form solutions of these two-view triangulation problems. Then, the Cramer-Rao lower bound (CRLB) is employed to calculate their covariances, according to which these solutions are fused to obtain the final result of the multiple-view triangulation. Our proposed algorithm is proved to be efficient based on the theoretical analysis, as it is linear and non-iterative. The simulations on both synthetic and real data show that the proposed algorithm can achieve competitive accuracy within less processing time, comparing with the most state-of-art algorithms.

MicroRNA-361 reduces the viability and migratory ability of pancreatic cancer cells via mediation of the MAPK/JNK pathway.

Previous research has revealed that microRNA-361 (miR-361) functions as a fundamental modulator in non-small-cell lung cancer and esophageal carcinoma. However, its involvement in pancreatic cancer (PC) is yet to be elucidated. Therefore, the present study aimed to examine the mechanism and function of miR-361 during the regulation of PC cell migration and viability. It was demonstrated that miR-361 expression decreased in PC cell lines and tissues, and the overexpression of miR-361 suppressed in vivo PC cell proliferation in mice. Moreover, flow cytometry and MTT assays indicated that the miR-361 mimic decreased the viability and increased the apoptosis of PC cells. Both Transwell migration and wound healing assays identified that miR-361 ameliorated the migratory ability of PC cells. Using dual-luciferase reporter assays, it was found that miR-361 targeted mitogen-activated protein kinase (MAPK)/JNK 3'-untranslated regions, inducing the downregulation of this gene. In PC cells, overexpression of MAPK/JNK diminished the pro-apoptotic effect of the miR-361 mimic, while restoring the migratory activity of PC cells. Collectively, the present results suggested novel molecular mechanisms underlying PC progression and development.

An improved switched‐ladder bidirectional multilevel inverter: Topology, operating principle, and implementation

AbstractMulti‐level inverters (MLIs) for medium or high power and voltage utilization have acceptable application in industry and are utilized commercially. The performance of MLIs is considerably preferable to traditional two‐level inverters due to their negligible harmonic content, small filter size, utilization of lower‐rated voltage devices, low electromagnetic interference (EMI), and so on. However, in the face of these many advantages, few disadvantages can be expressed such as more device count and a sophisticated control strategy. This paper presents an improved switched‐ladder topology to enhance the performance of multi‐level inverters by improving the above drawbacks. Compared to existing inverter topologies, the proposed extendable diode‐containing bidirectional structure requires fewer switches and driver circuits. The proposed topology is compared with other similar topologies, and its superiority is examined. Fundamental switching frequency modulation technique is utilized to obtain high‐quality output voltage waveforms with lower harmonic contents and reduced switching losses. This converter, despite the use of diodes, can supply the low power factor inductive‐resistive loads, bidirectionally. To demonstrate the performance of the proposed topology, in addition to simulation with the nearest level modulation technique, a prototype of the proposed structure has been implemented and tested. The results display the proper performance of the proposed topology in the real‐time environment.

Identification, Characterization, and Expression Analysis Reveal Diverse Regulated Roles of Three MAPK Genes in Chlamys farreri Under Heat Stress.

Mitogen-activated protein kinase (MAPK) cascades are fundamental signal transduction modules in all eukaryotic organisms, participating growth and development, as well as stress response. In the present study, three MAPK genes were successfully identified from the genome of Chlamys farreri, respectively, named CfERK1/2, CfJNK, and Cfp38, and only one copy of ERK, JNK, and p38 were detected. Domain analysis indicated that CfMAPKs possessed the typical domains, including S_TKc, Pkinase, and PKc_like domain. Phylogenetic analysis showed that three CfMAPKs of MAPK subfamilies exists in the common ancestor of vertebrates and invertebrates. All CfMAPKs specifically expressed during larval development and in adult tissues, and the expression level of CfERK1/2 and Cfp38 was apparently higher than that of CfJNK. Under heat stress, the expression of CfERK1/2 and Cfp38 were significantly downregulated and then upregulated in four tissues, while the expression of CfJNK increased in all tissues; these different expression patterns suggested a different molecular mechanism of CfMAPKs for bivalves to adapt to temperature changes. The diversity of CfMAPKs and their specific expression patterns provide valuable information for better understanding of the functions of MAPK cascades in bivalves.

Terahertz time-domain derivative spectrometer using a large-aperture piezoelectric micromachined device.

The engineering of optomechanical systems has exploded over the past decades, with many geometries and applications arising from the coupling of light with mechanical motion. The modulation of electromagnetic radiation in the terahertz (THz) frequency range through optomechanical systems is no exception to this research effort. However, some fundamental modulation capabilities for THz communications and/or high-speed data processing applications are yet to be established. Here, we demonstrate a THz time-domain derivative spectrometer based on a piezoelectric micromachined (PM) device. Insertion of the PM device into the THz beam path provides reference modulation for the lock-in detection unit, which in turn provides access to the nth-order derivative information of the incoming THz signal. Strikingly, the integration of the recorded derived signal leads to a recovered reference signal with an equivalent or even better signal-to-noise ratio, opening the door to a new type of highly sensitive THz measurements in the time domain.

A novel extended Kalman filter-based battery internal and surface temperature estimation based on an improved electro-thermal model

The lithium-ion battery temperature monitoring plays a prominent role in developing an appropriate battery thermal management system to ensure battery security, and improve battery performances, and it is also a vital fundamental module for the development of battery management system. To address this issue, this paper proposes a novel estimation procedure for the internal and surface temperatures of a lithium-ion battery cell based on an improved electro-thermal model (IETM). First, an electro-thermal model of lithium-ion battery is built up by combing the temperature-dependent electrical model and the two-state thermal model together. Then, the parameterization scheme of this IETM is carried out to facilitate the real-time estimation of the battery internal and surface temperatures. Furthermore, based on the extended Kalman filter (EKF), the battery IETM is employed to estimate both the battery internal and surface temperatures without requiring extra temperature sensors. Finally, the effectiveness and feasibility of the proposed battery temperature estimation method are demonstrated by performing the simulation and experiment verification.

Security Analysis and Improvement of a Redactable Consortium Blockchain for Industrial Internet-of-Things

Abstract A redactable consortium blockchain (RCB) can build a trust layer for industrial internet of things (IIoT) so as to enable IIoT to resist certain powerful attacks resulting in improper block content. The redactability is particularly important for blockchains applied in IIoT with valuable or sensitive activities such as financial IoT or energy-trading IoT. Huang et al. proposed a threshold chameleon hash (TCH) scheme and then constructed an accountable-and-sanitizable chameleon signature scheme based on TCH. These two primitives are further used as fundamental modules to build an RCB, which empowers IIoT devices to operate the blockchain in a controllable way. However, our paper shows that Huang et al.’s RCB suffers from a security problem that weakens the crucial redactability. Specifically, we find out that if a transaction in a given block is legally redacted by all authorized sensors who collectively hold the private redacting key, anyone (without any private information) can further redact this redacted transaction and delete any transaction within this redacted block and, meanwhile, any sensor user with a private signing (not redacting) key can insert a forged transaction into this redacted block. We further address this threat by replacing the TCH module in Huang et al.’s RCB with our designed TCH.

An improved control strategy for current source converter-based HVDC using fundamental frequency modulation

When pulse width modulation (PWM) is applied in a high-voltage current source converter (CSC) based on fully controlled devices, there are some concerns arising, such as large DC voltage fluctuations, high switching losses, and a narrow power operation range. To solve these problems, the CSC-based HVDC using fundamental frequency modulation (FFM-CSC) is proposed. First, the topology of the CSC is introduced. Then, an independent control strategy for FFM-CSC is presented, which can be used to realize univariate control of DC voltage or DC current. The mathematical model of CSC is also analyzed, and on this basis, a coordinated control strategy is proposed for FFM-CSC to decouple the active and reactive power. An outer loop power controller and an inner loop current controller are designed, and the power operation range is investigated. Finally, an FFM-CSC simulation model is built in PSCAD/EMTDC. The simulation results show that there are smaller DC voltage fluctuations, lower switching losses, and a wider power operation range under the proposed FFM-CSC control strategy.

A nine-switch nine-level converter new topology with optimal modulation control

<span lang="EN-US">Multilevel power converters are becoming increasingly used in several sectors: energy, grid-tie renewable energy systems, High voltage direct current (HVDC) power transmission, and a multitude of industrial applications. However, the multilevel converters consist of several drives and a high number of power switches, which leads to a considerable cost and an increased size of the device. Thus, a novel topology of a multilevel bidirectional inverter using a reduced number of semiconductor power components is proposed in this paper. Without any diode clamped or flying capacitor, only nine switches are used to generate nine voltage levels in this new topology. The proposed multilevel converter is compared with the conventional structures in terms of cost, the number of active power switches, clamped diodes, flying capacitors, DC floating capacitors, and the number of DC voltage sources. This comparative analysis shows that the proposed topology is suitable for many applications. For optimum control of this multilevel voltage inverter and to reduce switching losses in power semiconductors, a hybrid modulation technique based on fundamental frequency modulation and multi-carrier-based sinusoidal pulse-width modulation schemes is performed. The effectiveness of the proposed multilevel power converter is verified by simulation results.</span>

Superprotonic Conductivity of MOFs and Other Crystalline Platforms Beyond 10−1 S cm−1

AbstractThe proton‐exchange membrane (PEM) is a fundamental module of proton‐exchange membrane fuel cells (PEMFCs), permitting proton passage and thus governing the overall performance of PEMFCs. Till now, Nafion has been the extensively used marketable PEM material due to its high protonic conductivity of 10−2–10−1 S cm−1 under high relative humidity and 80–85 °C. On the other hand, crystalline materials such as metal‐organic frameworks (MOFs), coordination polymers (CPs), covalent organic frameworks (COFs), hydrogen‐bonded organic framework (HOFs), metalo hydrogen‐bonded organic framework (MHOFs), and polyoxometalates (POMs) are emerging as potential PEM materials, where crystallinity has paved the way to study the conduction pathway and associated mechanisms to understand structure‐function relationships. However, to date, ultrahigh superprotonic conductivity to the level of 10−1 S cm−1, close to Nafion, is relatively scarce for the crystalline proton conductors. In this review, the discussion is focused on materials that demonstrate a conductivity order of 10−1 S cm−1 and higher for those individual crystalline platforms (to be on the equal footing and superior to nafion, respectively) based on their synthesis approach while highlighting the design norms and key features for attaining such ultrahigh conductivity. While a critical analysis is made, the key issues and future prospects are also addressed.

C2C-GenDA: Cluster-to-Cluster Generation for Data Augmentation of Slot Filling

Slot filling, a fundamental module of spoken language understanding, often suffers from insufficient quantity and diversity of training data. To remedy this, we propose a novel Cluster-to-Cluster generation framework for Data Augmentation (DA), named C2C-GenDA. It enlarges the training set by reconstructing existing utterances into alternative expressions while keeping semantic. Different from previous DA works that reconstruct utterances one by one independently, C2C-GenDA jointly encodes multiple existing utterances of the same semantics and simultaneously decodes multiple unseen expressions. Jointly generating multiple new utterances allows to consider the relations between generated instances and encourages diversity. Besides, encoding multiple existing utterances endows C2C with a wider view of existing expressions, helping to reduce generation that duplicates existing data. Experiments on ATIS and Snips datasets show that instances augmented by C2C-GenDA improve slot filling by 7.99 (11.9%↑) and 5.76 (13.6%↑) F-scores respectively, when there are only hundreds of training utterances. Code: https://github.com/Sanyuan-Chen/C2C-DA.

Spectral Characteristics of Square-Wave-Modulated Type II Long-Period Fiber Gratings Inscribed by a Femtosecond Laser.

We study here the spectral characteristics of square-wave-modulated type II long-period fiber gratings (LPFGs) inscribed by a femtosecond laser. Both theoretical and experimental results indicate that higher-order harmonics refractive index (RI) modulation commonly exists together with the fundamental harmonic RI modulation in such LPFGs, and the duty cycle of a square wave has a great influence on the number and amplitudes of higher-order harmonics. A linear increase in the duty cycle in a series of square wave pulses will induce another LPFG with a minor difference in periods, which is useful for expanding the bandwidth of LPFGs. We also propose a method to reduce insertion loss by fabricating type II LPFGs without higher-order harmonic resonances. This work intensifies our comprehension of type II fiber gratings with which novel optical fiber sensors can be fabricated.

Postgraduate level analog microelectronics course based on cadence IC software and AMS 0.35 µm technology

An analog microelectronics design course at the post-graduate level is described in this paper. In 30 h, students with different engineering background receive a basic but solid formation by implementing a complete microelectronics design flow, following current industry standards. The course deals with fundamental design blocks as well as specific computer aided design tools. This course can be taught, as it is, as a fundamental module in general electronics/communications masters, but it can be also tuned to match specific curriculum constraints, if required. It has been successfully taught for two years, with minor adjustments, within the Telecommunications Engineering Master, at the University of Valencia, Spain. The assessments from the students highlight the acceptance of the course.

Novel Signaling Hub of Insulin Receptor Dystrophin Glycoprotein Complex and Plakoglobin Regulates Muscle Size

Signaling through the insulin receptor governs central physiological functions related to cell growth and metabolism. Here we show by tandem native protein complex purification approach and super-resolution STED microscopy that insulin receptor activity requires association with the fundamental structural module in muscle, the dystrophin glycoprotein complex (DGC), and the desmosomal component plakoglobin (γ-catenin). These protein assemblies are also present in heart and liver. The integrity of this high-molecular-mass assembly renders skeletal muscle susceptibility to insulin, because DGC-insulin receptor dissociation by plakoglobin downregulation reduces insulin signaling and causes atrophy. Furthermore, low insulin receptor activity in muscles from diabetic or fasted mice decreases plakoglobin-DGC-insulin receptor content on the plasma membrane, but not when plakoglobin is overexpressed. By masking β-dystroglycan LIR domains, plakoglobin prevents autophagic clearance of plakoglobin-DGC-insulin receptor co-assemblies and maintains their function. Our findings establish DGC as a signaling hub, and provide a possible mechanism for the insulin resistance in Duchenne Muscular Dystrophy, and for the cardiomyopathies seen with plakoglobin mutations.