Forward Switching Research Articles

Configuration Reversal Effect on Earth Resistivity Measurements in Parts of Birnin Kebbi, Northwestern Nigeria

An approach involving forward and reverse effects on earth resistivity measurements was carried out in some selected sites in the Birnin Kebbi area of Gwandu Formation Northwestern Nigeria. The primary objective of this research work was to investigate the relationship between the principle of reversibility of current, the potential difference in measuring earth’s resistivity, and determining the depth of penetration for various probes. Because of shallow, deep, and very deep penetration used to measure resistivity in both locations, a Schlumberger array with half of the maximum current electrode spacing (AB/2) of 70 m was used to measure a total of sixteen (16) depth-sounding data in a randomly distributed manner. An Excel chart of (x, y) scattered data was used to automatically interpret the apparent resistivity data after the field was examined and interpreted using IPI2win. To compare the apparent soil resistivity of two switches and how it’s impacted by the depth of the soil moisture contents, a series of measurements were made as part of this study. The collected results demonstrate how soil resistivity varies with depth and spacing, which guides the development of earthen protection plans for the worst-case scenarios. Based on the kind of soil and moisture content, it was found that resistivity varies. Reverse resistivity switch is higher than forward switch resistivity. According to the suggested design, there are 4 to 6 different forward switch circumstances that call for different numbers of earth electrodes.

Ultra-high energy storage density in PBSLZS antiferroelectric thick film ceramics

Superior recoverable energy density (Wrec) and efficiency (η) are crucial parameters for capacitors used in pulse-power devices. Here, we achieved an ultrahigh Wrec and high η in (Pb0.95-xBa0.02SrxLa0.02)(Zr0.65Sn0.35)O3 (PBSLZS) antiferroelectric thick film ceramics. All ceramics exhibit an orthorhombic structure, and the forward switching field increases with the increase of Sr2+ ionic content. The PBSLZS (x = 0.03) ceramics exhibit maximum value of total energy density (Wtot) and Wrec of 14.9 J/cm3 and 12.9 J/cm3, respectively, along with a high η of 86.6% at 570 kV/cm. Furthermore, we investigated the impact of multi-field coupling, i.e., the electric field and temperature, on the energy storage performance. An electric field (E) versus temperature (T) phase diagram was also obtained. The outstanding energy storage performance observed in PBSLZS ceramics demonstrates the potential for energy storage capacitors.

Asymmetric nucleation processes in spontaneous mode switch of active matter

Flocking and vortical are two typical motion modes in active matter. Although it is known that the two modes can spontaneously switch between each other in a finite-size system, the switching dynamics remain elusive. In this work, by computer simulation of a two-dimensional Vicsek-like system with 1000 particles, we find from the perspective of the classical nucleation theory that the forward and backward switching dynamics are asymmetric: going from flocking to vortical is a one-step nucleation process, while the opposite is a two-step nucleation process, with the system staying in a metastable state before reaching the final flocking state.

Photoconductivity and bandgap of binary impurity - doped crystalline silicon

The paper presents the results of study of the photoconductivity spectra of sulfur- and <sulfur+manganese>-doped samples of silicon (Si<S>, Si<MnS>) under dark conditions and while samples were subjected to constant light in forward and reverse switching modes. The paper also presents the calculation results of the value of the band gap (Eg ) of <sulfur+zinc> -doped silicon samples (Si<ZnS>). Spatial analogues of generally accepted GaAs structure such as Si2Mn2S and Si2Zn2S are hypothesized to be brought up in the result of above mixed dopings. Tentative investigations of the short-circuit current and open-circuit voltage of p-n-structures, as well as the photoconductivity of such structures, together with the analysis of their lux-ampere characteristic might serve for proposing potential varying band structures for solar cells.

Optimizing deposition regimes to fabricate VO2/TiO2/c-Al2O3 thin films for active metasurfaces

Decreasing the scale of vanadium dioxide (VO2) structures is one of the ways to enhance the switching speed of the material. We study the properties of VO2 films of altered thicknesses in the range of 20–170[Formula: see text]nm prepared on c-sapphire substrates with a TiO2 sublayer by pulsed laser deposition (PLD) method. The synthesis regime to design a TiO2 film was preliminarily optimized based on XRD data. XRD patterns reveal an epitaxial growth of the VO2 films with distortion of the monoclinic cell to hexagonal symmetry. The positions of the lattice vibration modes in Raman spectra are similar to those in bulk VO2 when the film thickness is greater than [Formula: see text][Formula: see text]nm. For VO2 films thicker that [Formula: see text][Formula: see text]nm, a lattice strain results in the modes’ positions and intensity change. However, the electrically triggered transition in a [Formula: see text][Formula: see text]nm thick VO2 film reveals forward and reverse switching times as short as 20[Formula: see text]ns and 400[Formula: see text]ns, correspondingly.

Fast Local Rules Based Switching and Routing Within Multidimensional Torus Interconnect

Multidimensional torus networking topology has become widespread recently in the domain of high-performance computers, clusters, and grids, as well as in the domain of networks on chip. Torus represents an ideal communication structure with the shortest distance and multitude of alternative shortest paths between a pair of nodes. We study simple and powerful local packet forwarding (switching) rules that provide packet delivery with quasi-optimal load balancing and do not use tables of addresses (routes). Implementation of these rules in the form of micro-program code within switching nodes increases considerably network performance, security, and QoS. We use infinite Petri nets and reenterable models in the form of colored Petri nets for prototyping the multi-dimensional torus interconnect simulator to study and compare the packet forwarding rules. Then, an ad-hoc simulator of torus interconnect ts is implemented in the C language to provide high performance and the possibility of simulation over prolonged intervals of time. The simulation results acknowledge the advantages of local packet forwarding rules.

Ultrahigh Energy Density of Antiferroelectric PbZrO3‐Based Films at Low Electric Field

AbstractDielectric capacitors play a vital role in advanced electronics and power systems as a medium of energy storage and conversion. Achieving ultrahigh energy density at low electric field/voltage, however, remains a challenge for insulating dielectric materials. Taking advantage of the phase transition in antiferroelectric (AFE) film PbZrO3(PZO), a small amount of isovalent (Sr2+) / aliovalent (La3+) dopants are introduced to form a hierarchical domain structure to increase the polarization and enhance the backward switching fieldEAsimultaneously, while maintaining a stable forward switching fieldEF. An ultrahigh energy density of 50 J cm−3is achieved for the nominal Pb0.925La0.05ZrO3(PLZ5) films at low electric fields of 1 MV cm−1, exceeding the current dielectric energy storage films at similar electric field. This study opens a new avenue to enhance energy density of AFE materials at low field/voltage based on a gradient‐relaxor AFE strategy, which has significant implications for the development of new dielectric materials that can operate at low field/voltage while still delivering high energy density.

Selective control of donor-acceptor Stenhouse adduct populations with non-selective stimuli

Selective control of donor-acceptor Stenhouse adduct populations with non-selective stimuli

Rough FTO electrode interface effect upon ferroelectric switching dynamics in Ag/P(VDF‐HFP)/FTO capacitor structures

AbstractRough FTO electrode interface effect upon the characteristic ferroelectric polarization parameters and switching dynamics in Ag/P(VDF‐HFP)/FTO junctions is systematically evaluated by varying electric field amplitude and frequency. Structural and microstructural studies confirm the ferroelectric phase formation of P(VDF‐HFP) on FTO surface. Tilted rectangular P‐E loops have been recorded in the applied fields ranging over 156.25–468.75 MV/m measured between 250 mHz and 5 Hz frequency ranges. Giant saturation of 21.7 μC/cm2 and remnant polarization of 34.9 μC/cm2 has been noted at low frequencies due to the influence of high electric field induced leakage currents. The coercive field, saturation and remnant polarization response with increase in electric field amplitude and frequency of the applied signal are well fitted with classic domain growth model proposed by Kolmogorov‐Avrami‐Ishibashi. A switching time scales of 32.2–693 ms has been observed for forward switching while for backward switching it is noted as 22.1–618.8 ms, when measured at frequencies from 5 Hz to 250 mHz. Furthermore, the tilted P‐E loops are attributed to the excessive leakage currents due to the high surface roughness of FTO bottom electrode.

Novel (1-x)NaNbO3-xBi2/3HfO3 based, lead-free compositions with stable antiferroelectric phase and high energy density and switching field

Pulse power devices urgently need lead-free compositions with stable antiferroelectric phase and transition field. Following the guidance of the DFT (Density Functional Theory) calculation, a novel antiferroelectric composition (1-x)NaNbO3-xBi2/3HfO3(0 ≤ x ≤ 0.08), was designed and prepared, exhibiting well-documented double AFE loops both in macro and nanoscale. Furthermore, Bi2/3HfO3 modified compositions also exhibit a high stored energy density of 4.26 J/cm3, forward switching field of 225 kV/cm, large discharge current of 36 A, within 25 ns discharge time and high power density of 32 MW/cm3, which is superior to other NaNbO3-based compositions reported in antiferroelectric range. Structural analysis shows that the high temperature phases of P and R can be rapidly shifted to room temperature by adding Bi2/3HfO3. Combining results from the PFM and TEM, the modified compositions had a faster domain switching speed to the electric field. In addition, theoretical calculations demonstrated that modified compositions have a predictable increasing energy difference −7.48 meV/f.u. between AFE(antiferroelectric) and FE(ferroelectric) phase.

Superior Energy and Power Density Realized in Pb(Hf 1- x Ti x )O 3 System at Low Electric Field

The development of antiferroelectric materials with large energy density and fast discharge speed makes dielectric capacitors possess great prospects for applications in pulsed power technology. Here, the PbHfO 3 -based ceramics with compositions of Pb(Hf 1- x Ti x )O 3 (PHT, 0.01 ≤ x ≤ 0.05) were synthesized, and their antiferroelectricity and phase transition behavior were studied. According to the tests of x-ray diffraction, dielectric spectrum, and polarization–electric field hysteresis loops, PHT ceramics gradually transition from an orthorhombic symmetric antiferroelectric phase to a hexagonal symmetric ferroelectric phase at room temperature as Ti 4+ concentration increases. The forward phase switching field of antiferroelectric to ferroelectric phase transition can be markedly regulated by the introduction of Ti 4+ , and the optimal energy storage performance was obtained in Pb(Hf 0.98 Ti 0.02 )O 3 ceramics with a large recoverable energy storage density of W rec ~ 4.15 J/cm 3 and efficiency of η ~ 65.3% only at a low electric field of 190 kV/cm. Furthermore, the outstanding charge–discharge properties with an ultrafast discharge time (71 ns), remarkable discharged energy density (2.84 J/cm 3 ), impressive current density (1,190 A/cm 2 ), and ultrahigh power density (101 MW/cm 3 ) at a low electric field of 170 kV/cm were obtained in studied ceramics. The excellent energy storage performance of PHT ceramics provides a promising platform for the application of dielectric capacitors.

Towards Securing OpenFlow Controllers for SDNs using ARMA Models

Control layers are moved away from the forwarding switching layers in Software Defined Networks. SDNs allow more programmability and flexibility to the controllers. OpenFlow is a protocol that gives access to the forwarding plane of a network switch or router over the SDN network. OpenFlow uses a centralized control of network switches and routers in SDN environment. Security is of a major importance for SDN deployment. Transport Layer Security (TLS) is be used to implement security for OpenFlow. This paper proposes a new technique to improve the security of the OpenFlow controller through modifying the TLS implementation. The proposed model is referred to as Secured Feedback model using Autoregressive Moving Average (ARMA) for SDN networks (SFBARMASDN). SFBARMASDN depends on computing the feedback for incoming packets based on ARMA models. Filtering techniques based on ARMA techniques are used to filter the packets and detect malicious packets to be dropped. SFBARMASDN is compared to two reference models. One reference model is based on Bayesian and the other reference model is the standard OpenFlow. Results are very promising. SFBARMASDN has outperformed both the secured standard using Bayesian network for SDN (SSBNSDN) and the standard OpenFlow in different scenarios by an average improvement of 7% and 80% respectively. The processing time overhead for the SFBARMASDN increases by only a percentage of 3% and 5% when compared to the SSBNSDN and the standard OpenFlow respectively.

Feedback ARMA Models versus Bayesian Models towards Securing OpenFlow Controllers for SDNs

In software-defined networking (SDN), the control layers are moved away from the forwarding switching layers. SDN gives more programmability and flexibility to the controllers. OpenFlow is a protocol that gives access to the forwarding plane of a network switch or router over the SDN network. OpenFlow uses a centralized control of network switches and routers in and SDN environment. Security is of major importance for SDN deployment. Transport layer security (TLS) is used to implement security for OpenFlow. This paper proposed a new technique to improve the security of the OpenFlow controller through modifying the TLS implementation. The proposed model is referred to as the secured feedback model using autoregressive moving average (ARMA) for SDN networks (SFBARMASDN). SFBARMASDN depended on computing the feedback for incoming packets based on ARMA models. Filtering techniques based on ARMA techniques were used to filter the packets and detect malicious packets that needed to be dropped. SFBARMASDN was compared to two reference models. One reference model was Bayesian-based and the other reference model was the standard OpenFlow.

Low-Complexity Multi-Size Circular-Shift Network for 5G New Radio LDPC Decoders.

This paper presents a low-complexity multi-size circular-shift network (MCSN) structure for 5th-generation (5G) New Radio (NR) quasi-cyclic low-density parity-check (QC-LDPC) decoders. In particular, a fine-coarse approach-based multi-size cyclic shift network, which decomposes the cyclic shift size into fine part and coarse part, is introduced. The proposed MCSN structure is composed of a pre-rotator performing the fine part of the cyclic shift, and a main rotator executing the coarse part of the cyclic shift. In addition, a forward routing circular-shift (FRCS) network, which is based on the barrel shifter and the forward routing process is presented. The proposed switch network is able to support all 51 different submatrix sizes as defined in the 5G NR standard through an efficient forward routing switch network and help reduce the hardware complexity using a cyclic shift size decomposition method. The proposed MCSN is analyzed, and indicates a substantial reduction in the hardware complexity. The experimental results on TSMC 65-nm CMOS technology show that the proposed MCSN structure for 5G NR LDPC decoder offers an area saving up to 56.75% compared to related works in the literature.

Provides an Approach based on Adaptive Forwarding and Label Switching to Improve the Speed of Packet Forwarding in NDN Networks

Provides an Approach based on Adaptive Forwarding and Label Switching to Improve the Speed of Packet Forwarding in NDN Networks

Provides an Approach based on Adaptive Forwarding and Label Switching to Improve the Speed of Packet Forwarding in NDN Networks

Named Data Networking (NDN) is a recently designed Internet architecture that benefits data names instead of locations and creates essential changes in the abstraction of network services from "delivering packets to specific destinations” to "retrieving data with special names" makes. This fundamental change creates new opportunities and intellectual challenges in all areas, especially network routing and communication, communication security, and privacy. The focus of this dissertation is on the forwarding aircraft feature introduced by NDN. Communication in NDN is done by exchanging interest and data packets. Consumers send interest packets to request data, routers send them based on the data prefix name, and manufacturers respond with data packets exactly how interest is received. During this process, routers maintain information about the status of suspended interests. As regards NDN is still in its early stage, none of these strong efficiency features have done systematically designed, measured, or tracked in data retrieval and multi-path detection. This paper tries to improve transport performance by combining label switching with adaptive transport methods. For this purpose, in addition to RTT, another timer called T is used, an RTT factor for interface rating. And uses the BDP to choose the best interface to respond to interest. During this process, response time, throughput, and data recovery time are improved by 12%, 10%, and 5%, respectively.

Natural history and patterns of treatment change in Parkinson’s disease: A retrospective chart review

BackgroundParkinson’s disease (PD) management seeks to balance the benefits and harms of current medications and evolves as the disease progresses. The natural history of PD and associated patterns of treatment change were analyzed to identify unmet needs in treatment of PD symptoms. MethodsMedical charts of patients from clinics across the US diagnosed on or before June 30th, 2014 were retrospectively reviewed. Index date was the first clinic visit, and the post-index period was through study end (June 30th, 2019). Outcomes included the frequency of therapy changes in the post-index period, reasons for therapy change, and adverse events (AE). ResultsPatients (n = 203) at index were receiving levodopa-peripheral dopa decarboxylase inhibitor (PDDI) monotherapy (47%), dopaminergic agonist (DA) monotherapy (15%), monoamine oxidase B inhibitor (MAOBI) monotherapy (14%), or combination therapies. The percentage of patients in Hoehn-Yahr disease Stage 1–2 was 52% at index and 20% by the end of the study. Frequencies of motor, non-motor, and neuropsychiatric symptoms increased during the enrollment. Levodopa-PDDI monotherapy and levodopa-PDDI + MAOBI had the lowest rates of therapy changes. Symptom relapse was the most common reason for dose escalation, add-on, and dose reduction, whereas AEs were the most common reason for discontinuation and switching. Dose escalation, add-on, and forward switch were most likely to occur in the first 6 months of treatment. ConclusionsTherapy changes during the study period reflected the challenging and evolving management of PD as the disease progresses. New or add-on symptomatic treatments are needed that are well-tolerated and able to control PD symptoms.

Frequency dependence of antiferroelectricferroelectric phase transition of PLZST ceramic

AbstractAntiferroelectric (AFE) ceramics are promising for applications in high‐power density capacitors, transducers, etc. The forward switching field and backward switching field are critical performance indicators for AFE ceramics, and the coupling between the structure transition and domain orientation makes them different from the coercive field of ferroelectric (FE). Moreover, in practical applications, AFE ceramics are often required to operate at varying frequencies. However, systematic studies regarding the frequency dependence of and are insufficient. In this work, (PLZST) AFE ceramic was fabricated, and two empirical formulas (, ) were proposed to predict the frequency dependence of and . The formulas are based on the electric field–induced phase transition characteristics of AFE and the Kolmogorov–Avrami–Ishibashi domain nucleation‐switching model. Furthermore, the dynamic hysteresis loops of PLZST at various frequencies (1–1000 Hz) and temperatures (–) were investigated. The results show that the electric field–induced phase transition of AFE ceramic is dominated by the coupling between the structural transition and domain orientation. The domain orientation hinders the structure transition, leading to an increase in and a decrease in as the frequency of applied electric field increases. Meanwhile, the domain growth process is affected by the structure of AFE, and the value of (domain growth dimensionality) increases with the stability of the AFE structure. For comparison, (PLBZST) relaxor FE ceramic was fabricated. Due to the high mobility of the microdomain, the dynamic hysteresis loop of PLBZST ceramic exhibits excellent frequency stability. The charge–discharge experiment with an ultrahigh equivalent frequency (100 kHz) was performed to investigate the frequency stability of energy release of PLZST and PLBZST. The results may provide guidance for research pertaining to ceramic capacitors with high‐power density and high‐frequency stability.

Intelligent Speed Regulation Control of Switched Reluctance Motor of Electric Vehicle Based on Neural Network Parameter Identification

Based on the analysis of the related theories of switched reluctance motor, this paper designs and implements the intelligent speed regulation system of switched reluctance motor for electric vehicle. The speed regulation system has the characteristics of high efficiency and energy saving, wide speed regulation range and small starting current. The system also has the advantages of large starting torque, frequent start and stop, forward and reverse switching, high torque / inertia ratio and four quadrant operation. The system can provide a good solution for variable speed drive. The digital controller of the system is composed of TMS320F2812 DSP and EPM7128S CPLD, which can realize the starting, electric and braking functions of electric vehicles. Experiments show that the switched reluctance motor drive system for electric vehicle has good control performance and strong fault tolerance. The system can meet the requirements of various working conditions of electric vehicles and has broad development prospects.

Insight into the Impact of Zr/Ti Ratios on the Structure and Properties of (Pb, La)(Zr, Sn, Ti)O3 Antiferroelectric Thick Films

In recent years, (Pb, La)(Zr, Sn, Ti)O3 (PLZST)‐based antiferroelectric (AFE) materials are examined, and research demonstrates that the content of each material component has a significant impact on performance. However, a majority of investigations focus on a 2 mol% La content. Herein, PLZST AFE thick films with 6 mol% La content and a changed Zr/Ti ratio are prepared using the rolling process (RP). The results show that antiferroelectricity decreases with increasing Ti content. The forward and backward switching electric fields decrease linearly. Meanwhile, the hysteresis is only slightly reduced, maintaining a relatively small value. Images of the microstructure reveal that the RP is a helpful method for preparing dense materials. The breakdown at the edge of the electrode is the leading electric failure mode. As Ti content is increased, the temperature‐dependent dielectric permittivity relationship curves remain almost equidistant and shift to the left. Compared with the others, the 2 mol% Ti content sample exhibits a better discharge performance. However, owing to the limited breakdown electric field, the discharge behavior beyond the electric switching field strength cannot be observed, so a high electric switching field strength material with an excellent voltage resistance is needed for an outstanding discharge performance.