Splitting Factor Research Articles

CONTROL OF WORKING BODY OF AIRBORNE AIRCRAFT POSITIONING MECHANISMS BY MEANS OF STEPPER MOTOR IN STEP CRUSHING MODE

Step splitting control mode of the electric drives stepper motors working bodies of the positioning mechanisms of onboard aviation equipment is carried out by means of programmable controllers. From their output signals, pulse-wide signals are formed by means of drivers that control power transistors, which are included in the windings of a stepper motor.
 A simpler version of building control systems for stepper motors (SM) involves the use of programmable timers, which requires its reprogramming when changing the step splitting factor.
 In the process of step splitting the shape of the current in the winding of the SM approaches sinusoidal with an increase in the number of sine discretes stored in the controller's memory. However, in this case, the sine samples must follow at a higher frequency, which difficulties in programming them.
 There is a problem of finding new ways of programming in the controller's memory information about the changing shape of the supply voltage SM in the process of step splitting in order to ensure the maximum speed of the code and the minimum consumption of the processor time of the microcontroller.
 To solve this problem, it is proposed to specify information about the changing shape of the SM supply voltage not in the form of sine samples (table method), but the sum of the coefficients of the Walsh-Fourier series, the amplitudes of which depend of value of the step splitting factor.
 The Walsh-Fourier series is a natural basis for approximating the pulsed supply voltage of a stepper motor. Structural diagrams of digital and analog systems for stepper motors in the step splitting are proposed.
 In the digital control system, the Walsh matrix is entered into the permanent memory of the controller, the size of which is determined by the value of the minimum step splitting factor, and the column vectors of the coefficients of the amplitudes of the Walsh functions are entered into the random-access memory, each of which corresponds to its step splitting factor.
 The input controller sets the program for implementing the inverse Walsh transform to the control controller, as a result of which control signals for the driver are generated at the output of the DAC controller. As its output, control signals are generated for power transistors including in the windings of the stepper motor.
 In the analog control system, the main links are the Walsh functions generator and the block of summing coefficients. In the block of summing coefficients of each Walsh function is assigned an amplitude corresponding to a given step splitting factor, and then they are summed. As a result, a pulsed voltage is formed, which is fed to the input of the driver, as in a digital system. It is shown that an analog control system can be used to form low-frequency quasi- sine signals of high stability. They can be used in precision electric drives with high stability.

EARS

Russian roulette and splitting are widely used techniques to increase the efficiency of Monte Carlo estimators. But, despite their popularity, there is little work on how to best apply them. Most existing approaches rely on simple heuristics based on, e.g., surface albedo and roughness. Their efficiency often hinges on user-controlled parameters. We instead iteratively learn optimal Russian roulette and splitting factors during rendering, using a simple and lightweight data structure. Given perfect estimates of variance and cost, our fixed-point iteration provably converges to the optimal Russian roulette and splitting factors that maximize the rendering efficiency. In our application to unidirectional path tracing, we achieve consistent and significant speed-ups over the state of the art.

A New Approach to the Splitting Factor Preconditioner Applied to Linear Programming Problems

In this paper, we present the results of a new approach to the splitting factor preconditioner, which is a preconditioner based on the Incomplete Cholesky factorization and the splitting preconditioner. In previous work for small linear programming problems, the preconditioner was applied in all iterations of the interior point method and compared with the splitting preconditioner also applied in all iterations. In this paper, we will do a hybrid approach, in which in the first iterations the preconditioner is the Incomplete Cholesky Factorization, and in the last iterations, the preconditioner used is the splitting factor preconditioner or the splitting preconditioner. The results obtained show that even in the hybrid approach, the splitting factor preconditioner achieved better performance.

Half-Duplex and Full-Duplex DF Wireless Energy Harvesting Relaying in Rayleigh Fading

With the further development and wide application of wireless technology in 6G, people are increasingly inseparable from wireless devices, from the ground to the air. The power consumption and service life of devices have become an urgent problem to be solved. In this paper, the energy harvesting relaying system based on the power splitting method with unidirectional DF half-duplex and full-duplex relay is proposed. The relay node is powered by itself through energy harvesting. Specifically, we analyze the system capacity, and the formula of system outage probability is also obtained. Simulation results show the performance of the half-duplex and full-duplex system. With a smaller power splitting factor, more energy is harvested, the outage probability is lower, and the capacity is higher.

Improved Rate-Energy Trade-Off for SWIPT Using Chordal Distance Decomposition in Interference Alignment Networks

This paper investigates the simultaneous wireless information and power transfer (SWIPT) precoding scheme for K-user multiple-input-multiple-output (MIMO) interference channels (IC), for which interference alignment (IA) schemes provide optimal precoders to achieve full degrees-of-freedom (DoF) gain. However, harvesting RF energy simultaneously reduces the achievable DoFs. To study a trade-off between harvested energy and sum rate, the transceiver design problem is suboptimally formulated in literature via convex relaxations, which is still computationally intensive, especially for battery limited nodes running on harvested energy. In this paper, we propose a systematic method using chordal distance (CD) decomposition to obtain the balanced precoding, which improves the trade-off. Analysis shows that given the nonnegative value of CD, the achieved harvested energy for the proposed precoder is higher than that for perfect IA precoder. Moreover, energy constraints can be achieved, while maintaining a constant rate loss without losing DoFs via tuning the CD value and splitting factor. Simulation results verify the analysis and add that the IA schemes based on max-SINR or mean-squared error are better suited for SWIPT maximization than subspace or leakage minimization methods.

Exploiting Incremental Virtual Full Duplex Non-Orthogonal Multiple Access Systems

This paper investigates the throughput performance of an incremental virtual full-duplex non-orthogonal multiple access (I-VFD-NOMA) communication system, where two energy harvesting (EH) enabled near users are willing to forward message for far user using decode-and-forward (DF) protocol. If the direct link between the source and the far user exists, I-VFD-NOMA scheme is used to save the channel resources. If the direct link between the source and the far user does not exist, I-VFD-NOMA can not be used and only VFD-NOMA can be used. With this structure, The analytical expressions of the system throughput considering imperfect successive interference cancellation (I-SIC) and selection combining (SC) are derived when the direct link exists or not. With the aim of maximizing the throughput, the expression for the optimal power splitting factor at near users is also derived when the direct link does not exist. All theoretical results are validated by numerical simulations which demonstrate that the proposed I-VFD-NOMA scheme is superior to existing NOMA systems.

Creating saturated sodium chloride solutions through osmotically assisted reverse osmosis

Increasing sustainability awareness has created opportunities for the recovery and reuse of salt solutions in industrial processes. Osmotically assisted reverse osmosis (OARO) has the potential to concentrate these salt solutions. Until now OARO research focussed on the production of purified water yielding an unsaturated salt solution as retentate, whereas a saturated salt solution is often needed for reuse. OARO featuring recycling of part of the saturated salt solution to the permeate side of the membrane has now been investigated. The introduction of a saturated NaCl solution results in strongly changing osmotic pressure difference and flux profiles along the length of the modules, with a maximum osmotic pressure difference and a minimum flux close to the outlet of the OARO system. In contrast to the NaCl retention of the membrane, the NaCl feed concentration does not have an influence on the maximum osmotic pressure difference. The osmotic pressure difference and membrane flux are strongly dependent on the applied concentrate split factor, which has a strong effect on the required membrane area per feed flow supplied as well. The amount of surface area required per flow of saturated NaCl solution leaving the OARO unit has an optimum as function of the concentrate split factor. This is due to two counteracting effects, the lower osmotic pressure difference, and the lower fraction of saturated NaCl solution leaving the OARO for a higher concentrate split factor. Based on the modelling, essential knowledge has been generated for the further research and development of OARO.

Energy‐efficient alternating current computing‐enabled receiver design for K‐user interference channel simultaneous wireless information and power transfer networks

SummaryEnergy efficiency is one of the key challenges in fifth generation (5G) and beyond wireless communication systems. Recently, simultaneous wireless information and power transfer (SWIPT) systems are usually adopted to enhance energy efficiency. The harvested energy through power transfer is first rectified to generate the direct current (DC) voltage that is used to power the communication devices. This rectification reduces the energy efficiency due to losses in conversion to DC voltages. In this work, we consider integrated information decoding and energy harvesting receiver architecture through power splitting SWIPT network that enables alternating current (AC) computational logic. The AC computing method is used to supply the computing block of receivers to further enhance the energy efficiency. Multiuser multiple input single output (MISO) interference channel (IC) is considered, where receivers are required to compromise between quality of service (QoS) and energy consumption. The system sum rate is maximized under sum harvested energy and total transmit power constraints through joint beamforming and power splitting factors design. For the problem tractability in the proposed AC computing‐enabled receiver, standard beamforming schemes are deployed, namely, zero forcing (ZF), regularized zero forcing (RZF), maximum ratio transmission (MRT), and a hybrid scheme between MRT and ZF beamforming (MRT‐ZF). Moreover, the power splitting ratios design problem is transformed into a one dimension search problem. Simulation results show that different beamforming designs exhibit a great trade‐off between the achieved rate and the harvested energy.

Precoder Design for Physical-Layer Security and Authentication in Massive MIMO UAV Communications

Supporting reliable and seamless wireless connectivity for unmanned aerial vehicles (UAVs) has recently become a critical requirement to enable various different use cases of UAVs. Due to their widespread deployment footprint, cellular networks can support beyond visual line of sight (BVLOS) communications for UAVs. In this paper, we consider cellular connected UAVs (C-UAVs) that are served by massive multiple-input-multiple-output (MIMO) links to extend coverage range, while also improving physical layer security and authentication. We consider Rician channel and propose a novel linear precoder design for transmitting data and artificial noise (AN). We derive the closed-form expression of the ergodic secrecy rate of C-UAVs for both conventional and proposed precoder designs. In addition, we obtain the optimal power splitting factor that divides the power between data and AN by asymptotic analysis. Then, we apply the proposed precoder design in the fingerprint embedding authentication framework, where the goal is to minimize the probability of detection of the authentication tag at an eavesdropper. In simulation results, we show the superiority of the proposed precoder in both secrecy rate and the authentication probability considering moderate and large number of antenna massive MIMO scenarios.

A note on HOMFLY polynomial of positive braid links

For a positive braid link, a link represented as a closed positive braid, we determine the first few coefficients of its HOMFLY polynomial in terms of geometric invariants such as, the maximum Euler characteristics, the number of split factors, and the number of prime factors. Our results give improvements of known results for the Conway and the Jones polynomial of positive braid links. In Appendix, we present a simpler proof of theorem of Cromwell, a positive braid diagram represents a composite link if and only if the diagram is composite.

Adaptivity for clustering-based reduced-order modeling of localized history-dependent phenomena

This article introduces adaptivity in Clustering-based Reduced Order Models (ACROMs). The strategy is demonstrated for a particular CROM called Self-Consistent Clustering Analysis (SCA), extending it into the Adaptive Self-Consistent Clustering Analysis (ASCA) method. This is shown to improve predictions of Representative Volume Elements (RVEs) of materials exhibiting history-dependent localization phenomena such as plasticity, damage and fracture. The overall approach is composed of three main building blocks: target clusters selection criterion, adaptive cluster analysis, and computation of cluster interaction tensors. In addition, an adaptive clustering solution rewinding procedure and a dynamic adaptivity split factor strategy are suggested to further enhance the adaptive process. The ASCA method is shown to perform better than its static counterpart when capturing the multi-scale elasto-plastic behavior of a particle–matrix composite and predicting the associated fracture and toughness. The proposed adaptivity strategy can be followed in other CROMs to extend them into ACROMs, opening new avenues to explore adaptivity in this context.

Throughput analysis of dual hop hybrid RF-VLC system with wireless energy harvesting

Abstract In this paper, we study a dual hop hybrid radio frequency-visible light communication (RF-VLC) system with wireless energy harvesting technique. In the proposed model the RF channel and the VLC channel are modelled by generalized-K distribution and lambertian emission model, respectively. A decode and forward relay is used as an intermediate node where power splitting relaying (PSR) protocol is employed to harvest energy from the received RF information signal. The source transmits the information signal towards the relay via RF channel. The relay then decodes the received signal and convert it into corresponding light signal. Simultaneously the energy harvesting circuit at relay harvests the energy from the received RF signal. The relay utilizes the harvested energy to aid the transmission of the light signal towards the user situated inside the building’s room at the destination. Further, the statistics of the instantaneous SNR of the hybrid RF-VLC system at the destination are derived by employing the PSR protocol to obtain an accurate closed form analytical expression for the system’s end-to-end ergodic capacity and achievable throughput in terms of Meijer’s G function. Further, with the help of numerical simulations, we analysed the end-to-end ergodic throughput performance of the hybrid system under the influence of varying channel parameters such as signal to noise ratio, power splitting factor, shadowing parameters, distance between source & relay and source transmitted power.

Optimal Cooperative Transmission for Overlay Cognitive Satellite Terrestrial Networks

In this letter, we investigate an overlay cognitive satellite terrestrial network, where the secondary terrestrial network cooperates with the primary satellite network for spectrum access in a time splitting manner. To maximize the spectrum efficiency of such a cooperative cognitive network, we propose an optimal cooperative transmission scheme by optimizing the time splitting factors. Specifically, we firstly analyze the feasible range of time splitting factors to guarantee both transmission requirements of the satellite and terrestrial networks. On this basis, we decompose the non-concave optimization problem into several categories and employ the Charnes-Cooper transformation to determine the optimal time splitting factors.

On circulant and skew-circulant splitting algorithms for (continuous) Sylvester equations

We present a circulant and skew-circulant splitting (CSCS) iterative method for solving large sparse continuous Sylvester equations AX+XB=C, where the coefficient matrices A and B are Toeplitz matrices. A theoretical study shows that if the circulant and skew-circulant splitting factors of A and B are positive semi-definite (not necessarily Hermitian), and at least one factor is positive definite, then the CSCS method converges to the unique solution of the Sylvester equation. In addition, our analysis gives an upper bound for the convergence factor of the CSCS iteration which depends only on the eigenvalues of the circulant and skew-circulant splitting matrices. A computational comparison with alternative methods reveals the efficiency and reliability of the proposed method.

Effect of Steel-Nylon Fibre as Reinforcing Material on Strength Characteristics of Concrete

Concrete is reinforced using different kind of admixtures in order to increase its properties and making it cost effective. Fibre is one type of reinforcement, which is a composite material made up of cement or mortar and fragmented, separate, distributed, arbitrarily located, and disconnected reasonable fibres. Concrete is broadly utilized as a part of structural designing with its high compressive strength, minimal effort and bottomless crude material. However, regular cement has a few weaknesses, for instance, low malleability, restricted flexibility, little protection from splitting, weak hardness, high fragility, and other factors limits its use.” The cement may get split because of basic and natural properties; however, a large portion of the breaks are shaped because of inherent inward smaller scale breaks as well as the material’s inherent flaws to oppose ductile powers. Such condition of the structure at the tensile end subjects to the cracks under a certain amount of load. Initially there become small splits or cracks and with due respect of time these cracks gets widened. After drying of cement, Cracks may be developed due to shrinkage. The small-scale splits frame because of drying shrinkage or different reasons for volume change if there should be an occurrence of plain concrete. Along these lines many endeavours have been made to expand the rigidity of cement by method for utilizing traditional strengthened steel bars and furthermore by applying limiting systems.

Exploiting the Gal4/UAS System as Plant Orthogonal Molecular Toolbox to Control Reporter Expression in Arabidopsis Protoplasts.

The ability of protein domains to fold independently from the rest of the polypeptide is the principle governing the generation of fusion proteins with customized functions. A clear example is the split transcription factor system based on the yeast GAL4 protein and its cognate UAS enhancer. The rare occurrence of the UAS element in the transcriptionally sensitive regions of the Arabidopsis genome makes this transcription factor an ideal orthogonal platform to control reporter induction. Moreover, heterodimeric transcriptional complexes can be generated by exploiting posttranslational modifications hampering or promoting the interaction between GAL4-fused transcriptional partners, whenever this leads to the reconstitution of a fully functional GAL4 factor.The assembly of multiple engineered proteins into a synthetic transcriptional complex requires preliminary testing, before its components can be stably introduced into the plant genome. Mesophyll protoplast transformation represents a fast and reliable technique to test and optimize synthetic regulatory modules. Remarkable properties are the possibility to transform different combinations of plasmids (co-transformation) and the physiological resemblance of these isolated cells with the original tissue.Here we describe an extensive protocol to produce and exploit Arabidopsis mesophyll protoplasts to investigate the transcriptional output of GAL4/UAS-based complexes that are sensitive to posttranslational protein modifications.

STRUCTURAL, OPTICAL, AND PARAMAGNETIC INVESTIGATIONS OF (Mn2+) IONS DOPED ZINCALUMINOBOROPHOSPHATE (ZnAlBP) GLASS SYSTEM

Concentration variation of Mn2+ ions doped zincaluminoborophosphate (ZnAlBP) glasses of 40 ZnO + 25 H3BO3 + (30-x) P2O5 + 5 Al2O3 + x MnO with 0  x  0.8 (x=0, 0.2, 0.4, 0.6 and 0.8) have been prepared and investigated by structural and spectroscopic techniques. The XRD diffractograms confirm the amorphous nature of the prepared samples. The FTIR spectra reveal the existence of BO3 and BO4 units along with fundamental P-O-H and B-O-H structural units in the present glass system. The Optical absorption spectra exhibit two low intensity bands centered at 407 nm (24,570 cm-1) and 689 (14,514 cm-1). These bands were assigned to 6A1g(S) → 4A1g (G) + 4Eg (G) and6A1g(S) → 4T1g (G) characteristic transitions of Mn2+ ions in octahedral symmetry. Tauc’s plots were drawn to measure the optical band gaps for the direct and indirect transitions. The energy gaps show a decreasing trend for the selected ZnAlBP: Mn2+ glass system. The well-resolved hyperfine splitting EPR spectra of prepared glass samples exhibit resonance at g ≈ 1.98 indicating the Mn2+ ions are in octahedral site symmetry. The hyperfine splitting factor (hfs), the number of spin levels (N), hyperfine constant (A), zero-field splitting parameter (D), and paramagnetic susceptibility (χ) have been determined. The magnitude of g indicates the predominant ionicity in the glasses.

On Securing Cognitive Radio Networks-Enabled SWIPT Over Cascaded $\kappa$-$\mu$ Fading Channels With Multiple Eavesdroppers

In this paper, the physical-layer security (PLS) for an underlay cognitive radio network (CRN) with multiple non-colluding eavesdroppers is studied. We assume that a secondary user (SU) transmitter communicates with an SU receiver over a cascaded <inline-formula><tex-math notation="LaTeX">$\kappa$</tex-math></inline-formula>-<inline-formula><tex-math notation="LaTeX">$\mu$</tex-math></inline-formula> fading channel and under the threat of eavesdropping. A cooperative jammer exists to improve the SUs&#x2019; security by harvesting energy from the SU transmitter using power splitting technique. This harvested energy is utilized to generate jamming signals to deteriorate the eavesdroppers&#x2019; reception quality. Moreover, the eavesdroppers are assumed to be randomly distributed according to a homogeneous Poisson point process (HPPP), in which the <inline-formula><tex-math notation="LaTeX">$k^{th}$</tex-math></inline-formula> closest eavesdropper to the SU transmitter will be selected in our analysis. Additionally, the legitimate receiver is assumed to harvest energy from the SU transmitter using the power splitting technique. In this context, we propose an optimum power splitting factor at the legitimate receiver that achieves the best privacy while constraining the amount of the harvested energy. Furthermore, on enhancing system security, we investigate the effectiveness of the jamming technique. The impact of distances over security is also examined. The results reveal an improvement in privacy as the legitimate receiver utilizes the adaptable power splitting factor. PLS is evaluated in terms of the probability of non-zero secrecy capacity and the intercept probability.

Security Optimization for an AF MIMO Two-Way Relay-Assisted Cognitive Radio Nonorthogonal Multiple Access Networks With SWIPT

This paper investigates the physical layer security issue in an amplify-and-forward (AF) multi-input multi-output (MIMO) two-way relay assisted cognitive radio (CR) nonorthogonal multiple access (NOMA) network, where the simultaneous wireless information and power transfer (SWIPT) technology is employed to improve network energy efficiency. We consider the scenario that a pair of primary users and two pairs of secondary users (SUs) exchange information via a MIMO two-way relay, where the edge SU of each SU pair is untrusted and tries to wiretap the central SU’s information. For ensuring security, we aim to maximize the sum achievable secrecy rate (SASR) by jointly optimizing the power allocation at all users, power splitting factor and relay beamforming subject to the quality of service (QoS), energy harvesting and transmit power constraints. The formulated optimization problem is highly nonconvex due to coupling variables, thus it is challenging to solve. An effective path-following (PF)-based algorithm is proposed, which is proven to converge to a stationary point. Theoretical and simulation results show that the proposed PF-based algorithm has lower complexity than the state-of-art algorithm. To further reduce complexity, we proposed a zero-forcing (ZF)-based scheme. Numerical simulations show that the proposed PF-based algorithm achieves the same SASR as the state-of-art algorithm with moderate complexity, while the proposed ZF-based scheme strikes a good balance between performance and complexity.

Minimum Energy Adaptive Load Sharing of Parallel Operated Compressors

Compressors operating in parallel are widely used in compressor stations on natural gas pipelines to address the required flow demands. This paper presents a design of a new control structure and a load sharing optimal adaptive controller for multiple compressors connected in parallel and equipped with variable speed drives. The load sharing optimization (LSO) controller computes the split factor to distribute the flow among the compressors which depends on the current operating conditions, with the optimization&#x0027;s objective being to minimize the total energy consumption. In addition, the compressor maps are continuously updated to account for any changes due to external and untraceable factors resulting in an enhancement of the LSO. The presented control structure includes a common single controller for parallel compressors, which eliminates the need for loop-decoupling. Thus, ensuring a better stability and a faster dynamics with respect to the flow or pressure process variable. The proposed control structure and the adaptive LSO performance is evaluated through simulations and a lab hardware setup. The results show an improvement of more than 4&#x0025; in the total energy consumption compared to an equal load sharing scheme and more than 2.5&#x0025; compared to the equal distance to surge industrial scheme. This efficiency improvement leads to significant energy cost saving over large periods of time.