Interference Limit Research Articles

A Top-Down Survey on Optical Wireless Communications for the Internet of Things

The Internet of Things (IoT) is a transformative technology marking the beginning of a new era where physical, biological, and digital worlds are integrated by connecting a plethora of uniquely identifiable smart objects. Although the Internet of Terrestrial Things (IoTT) has been at the center of our IoT perception, it has been recently extended to different environments, such as the Internet of Underwater Things (IoWT), the Internet of Biomedical Things (IoBT), and Internet of Underground Things (IoGT). Even though radio frequency (RF) based wireless networks are regarded as the default means of connectivity, they are not always the best option due to the limited spectrum, interference limitations caused by the ever-increasing number of devices, and severe propagation loss in transmission mediums other than air. As a remedy, optical wireless communication (OWC) technologies can complement, replace, or co-exist with audio and radio wave-based wireless systems to improve overall network performance. To this aim, this paper reveals the full potential of OWC-based IoT networks by providing a top-down survey of four main IoT domains: IoTT, IoWT, IoBT, and IoGT. Each domain is covered by a dedicated and self-contained section that starts with a comparative analysis, explains how OWC can be hybridized with existing wireless technologies, points out potential OWC applications fitting best the related IoT domain, and discusses open communication and networking research problems. More importantly, instead of presenting a visionary OWC-IoT framework, the survey discloses that OWC-IoT has become a reality by emphasizing ongoing proof-of-concept prototyping efforts and available commercial off-the-shelf (COTS) OWC-IoT products.

Методика комплектования деталей соединений «Вал-уплотнение» при ремонте

The reliability of modern sealing units of agricultural machinery is insufficient. Due to surface wear of the shaft and the seal during operation, the tightness in the movable joint decreases. This condition leads to the onset of leaks and the assembly failure. Leaks of technical fluids in units account for 20 to 30% of the total number of failures; during the overhaul period, seal failures occur 1.5 times more often than in new equipment. The method of completing the parts of shaft connections with seals will be useful for assigning rational repair dimensions of the shafts and selecting suitable seals. For its development, the authors considered the main ways to ensure the operational reliability of shaft connections, including advanced methods for restoring the shaft surface. When developing the method, 100 worn input shafts of the YaMZ‑239 engine gearbox and 100 new seals 1.2‑52´72‑8 were studied. Measurements were taken of the worn surface of the shaft under the seal and the inner diameters of the seal holes. The wear of the shaft surface under the seals reached 0.5 mm, and the probability of the shafts with wear exceeding the allowable 51.7 mm was 33%. When assembling worn shafts with new seals, the spread of interference ranged from 1.7 to 3 mm. At the same time, the limit of the least tightness, equal to 2 mm, was violated in 15% of the connections. In the connections of new seals with shafts machined to a repair size of 51.4 mm, the spread of interference ranged between 1.6 mm and 3 mm, while the limit of the least interference was violated in 20% of the connections. According to the criterion of maintaining the least tightness in the connection, the method of completing the parts of the “shaft-seal” connection was tested, including the calculation of the number of groups, the assignment of shaft repair dimensions and the selection of seal diameters. As a result, the probability of appearing connections with a guaranteed tightness of at least 2 microns was 88%, therefore, the proposed method of selecting shafts and seals makes it possible to make the durability of shaft-seal connections comparable to the new ones.

Legendre Polynomials-Based Displacement Field Reconstruction of Plate-Type Structures With Quasi-Distributed FBG Sensors

Structural deformation estimation is of great interest for many engineering fields, such as aerospace structures, antenna panels, and so on. During operation, however, the direct measurement of global displacements is often difficult, due to the limits of installation space and electromagnetic interference. This article proposed a displacement field reconstruction method for deformed plate-type structures using discrete curvature measurements and a polynomial superposition approach. Specifically, the displacement field is expressed as a linear superposition of the Legendre polynomial basis functions, where the weight coefficients are calculated using the discrete curvatures captured by a quasi-distributed fiber Bragg grating (FBG) sensor array and the given boundary conditions. This method overcomes the drawback of error accumulation in other curvature-based methods due to the use of recursion operations. In addition, the curvature fitting and the determination of the number of polynomial basis functions were also presented to obtain the best reconstruction quality. Simulations and experiments have been conducted to validate the proposed method. The simulation results show that the displacement reconstruction precisions are more than 99% for two types of complex deformations. Experiments were carried out on an aluminum plate and a phased-array antenna panel, respectively. The results show that the reconstructed displacements of the reference points match well with those measured displacements, and the reconstruction precision exceeds 96%. This proposed curvature-based approach has high potential to global displacement monitoring of plate-type structures used in aerospace and antenna industrial fields.

Terahertz Super-Resolution Nondestructive Detection Algorithm Based on Edge Feature Convolution Network

Much research has been conducted to improve the defect-detection rate and detection accuracy of the imaging technology used in terahertz nondestructive testing. Due to the power limit of light sources and noise interference in terahertz equipment, images have low resolution and fuzzy defect edges. Hence, improving the resolution is crucial for detecting defects. We designed an edge detection network structure based on a traditional deep neural network. Besides, we devised a node-fusing strategy to train the network. It demonstrates significant improvement of the resolution of the terahertz defect contour. A quartz fiber composites with embedded defects was tested with our network. The results showed that the proposed super-resolution reconstruction algorithm improves resolution, particularly on the edges of defect contours.

Zakres ochrony prawa własności wynikający z art. 17 ust. 1 Karty praw podstawowych Unii Europejskiej a orzecznictwo polskich sądów administracyjnych

The right to property is one of the fundamental rights regulated by the European Union. Although the EU legal system doesn’t contain the very definition of ownership, by deleting in Art. 17 sec. 1 of the EU Charter of Fundamental Rights, the limits of interference with this right are defined by a clear and impassable boundary for the national laws of the EU Member States as to the scope of the interference. The Polish law system meets the requirements of Art. 17 sec. 1 of the Charter, guaranteeing the owner both the scope of shaping the right to property right up to the limits of violating its essence, and the possibility of expropriation only for public purposes and for just compensation. Both the restrictive interpretation of the public purpose and the observance of the determination of fair compensation by administrative courts fully fall within the scope of Art. 17 sec. 1 and art. 52 sec. 1 of the Charter. Not always just compensation will be full compensation, which, however, is not contrary to EU law. The role of the Polish Administrative Courts is to comply with the provisions of the Charter of Fundamental Rights in the scope of ensuring that owners have proper protection of their property rights, and to assess whether domestic legislation is not inconsistent with the provisions of this Charter. If is it found that a specific statutory provision violates the content of, for example, art. 17 sec. 1 of the Charter, administrative courts should apply the provisions of the Charter of Fundamental Rights, relying on the principle of primacy of primary EU law.

Energy-Efficient Initial Deployment and ML-Based Postdeployment Strategy for UAV Network With Guaranteed QoS

Nowadays, the extensive use of unmanned aerial vehicle (UAV)-enabled networks in different applications demands intelligent deployment planning to utilize several benefits of UAVs. This article proposes a complete solution for deploying a UAV network over an unprecedented public meet-up area that offers a guaranteed quality-of-service demand with no interference and capacity limit violation. We call that the proposed solution is complete as it includes both initial and postdeployment planning. Under initial deployment, we offer three different placement algorithms, known as anticlockwise spiral algorithm, clockwise spiral algorithm, and hexagonal circle packing algorithm, to determine the energy-efficient 3-D positions of capacity-limited UAVs with no inter-UAV interference. After deployment, the random walk by users demands postdeployment planning for UAVs. We propose a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$Q$</tex-math></inline-formula> -learning-based algorithm to realign the existing UAVs to maintain the outage. In order to do a more realistic performance assessment of the proposed algorithms, we model the user distribution for a hotspot region by the Thomas cluster point process and the Matern cluster point process. The obtained results exhibit that all three initial deployment algorithms show better performance than a random deployment. The <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$Q$</tex-math></inline-formula> -learning algorithm under postdeployment offers network lifetime enhancement in addition to outage improvement.

An equivalent surface dipoles based electric field to magnetic field transformations for estimating radiated emissions

The new generation of communication devices operating in higher frequency bands is constantly pushing the complexity of field measurements for electromagnetic compliance and the design of field probes. These compliance are to be met for both electric and magnetic fields, of which if one set is available, the other can be estimated computationally using source reconstruction algorithms. The main objective of this paper is to refine the dipole-based source reconstruction algorithms using surface equivalence principle. Compared to earlier works, the algorithm is based on a novel way of placing a single dipole per point tangentially to a fictitious surface based on surface equivalence theorem instead of multiple orthogonal dipoles per point. The numerical results are compared with the state-of-art to demonstrate the effectiveness in obtaining accurate fields and locating the regions of the Device Under Test responsible for overshooting the interference limits.

INS/GPS Integrated Navigation for Unmanned Ships Based on EEMD Noise Reduction and SSA-ELM

The primary problem faced by the integrated navigation system based on the inertial navigation system (INS) and global positioning system (GPS) is providing reliable navigation and positioning solutions during GPS failure. Thus, this study proposes an innovative integrated navigation algorithm to address the limitation of precise positioning when GPS fails. First, for the limitation of noise interference in INS, noise reduction technology based on ensemble empirical mode decomposition (EEMD) is proposed to improve the quality of the INS signal and enhance the noise reduction effect. Second, an INS/GPS integrated framework based on the sparrow search algorithm (SSA) and extreme learning machine (ELM) is proposed. During normal GPS conditions, SSA-ELM is used to develop a high-precision prediction model to estimate differences between INS and GPS. When the GPS signal is interrupted, the difference predicted by SSA-ELM is used as the measurement input and the INS is corrected. To confirm the effectiveness of this method, a real ship experiment is conducted with other commonly used methods. The experimental results demonstrate that the proposed method can improve positioning accuracy and reliability when GPS is interrupted.

Design of an Indirectly Coupled Filter Building Block for Modular Interleaved AC–DC Converters

This article presents the analysis and realization of a modular interconnected filter building block (FBB) operating under a single and multichannel (parallel three-phase converter blocks) configuration without loss of attenuation to any harmonic components. Emphasis is on the design of coupled inductor (CI) and boost inductor. In order to achieve a modular scheme with interleaved operation, indirect coupling between converters is realized using the secondary loop (SL)-based interconnection with inserted impedance. Here the “SL” serves as an additional pass for average grid side currents for <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i> channels. A building block type configuration has been proposed using this topology, inspired by the power electronics building block (PEBB) nature. The purpose of the loop is to interconnect the parallel converters in series using an arrangement of CIs. In addition, a boost inductor has been introduced in the SL to realize a power factor correction rectifier operation. The CI serves as the circulating current filter while reflecting channel currents toward the SL. To meet conducted electromagnetic interference (EMI) limits, a two-stage <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCLC</i> filter has been integrated with the FBB by introducing the point of common coupling (PCC) connection between two stages for filter size reduction. A design procedure is presented to meet power quality, circulating current, and EMI limits as per industry standards (EN-55011 and IEEE-519/1594). The proposed FBB has been characterized using 3L-NPC converters enabled with 1.2 kV Silicon Carbide based modules with comprehensive performance validation up to three channels in parallel with 15-kW power rating per channel.

An Automatic Velocity Analysis Method for Seismic Data-Containing Multiples

Normal moveout (NMO)-based velocity analysis can provide macro velocity models for prestack data processing and seismic attribute inversion. Datasets with an increasing size require conventional velocity analysis to be transformed to a more automatic mode. The sensitivity to multiple reflections limits the wide application of automatic velocity analysis. Thus, we propose an automatic velocity analysis method for seismic data-containing multiples to overcome the limit of multiple interference. The core idea of the proposed algorithm is to utilize a multi-attribute analysis system to transform the multiple attenuation problem to a multiple identification problem. To solve the identification problem, we introduce the local similarity to attribute the predicted multiples and build a quantitative attribute called multiple similarity. Considering robustness and accuracy, we select two supplementary attributes based on velocity and amplitude difference, i.e., velocity variation with depth and amplitude level. Then we utilize the technique for order preference by similarity to ideal solution (TOPSIS) to balance weights for different attributes in automatic velocity analysis. An RGB system is adopted for multi-attributes fusion in velocity spectra for visualization and quality control. Using both synthetic and field examples to evaluate the effectiveness of the proposed method for data-containing multiples, the results demonstrate the excellent performance in the accuracy of the extracted velocity model.

Vantera Mediated Quantification of Urine Citrate and Creatinine: A New Technology to Assess Risk of Nephrolithiasis.

Urine citrate is often used to identify patients at risk of recurrent nephrolithiasis or kidney stones. A high-throughput assay was developed to measure urine citrate and creatinine on the Vantera® Clinical Analyzer, a nuclear magnetic resonance (NMR) instrument designed for the clinical laboratory. Assay performance was evaluated and comparisons between the NMR and chemistry results were conducted. Linearity was demonstrated over a wide range of concentrations for citrate (6 and 2040 mg/L) and creatinine (2.8 and 1308 mg/dL). Intra-and inter-assay precision (%CV) ranged from 0.9 to 3.7% for citrate and 0.4 to 2.1% for creatinine. The correlation coefficients for the comparison between NMR and chemistry results were 0.98 (Y = 1.00X + 5.0) for citrate and 0.96 (Y = 0.968X + 0.97) for creatinine. The reference intervals for both analytes were confirmed. Ten endogenous and exogenous substances were tested and none were found to interfere with the assay results. In conclusion, the newly developed high-throughput NMR assay exhibited robust performance and generated results comparable to the currently utilized chemistry tests, thereby providing an alternative means to simultaneously quantify urine citrate and creatinine for clinical and research use. Furthermore, the NMR assay does not exhibit the same interference limitations as the chemistry tests and it enables multiplexing with other urine metabolite assays which saves time and costs.

Aryl-Phenanthro[9,10-d]imidazole: A Versatile Scaffold for the Design of Optical-Based Sensors.

Fluorescent and colorimetric sensors are important tools for investigating the chemical compositions of different matrices, including foods, environmental samples, and water. The high sensitivity, low interference, and low detection limits of these sensors have inspired scientists to investigate this class of sensing molecules for ion and molecule detection. Several examples of fluorescent and colorimetric sensors have been described in the literature; this Review focuses particularly on phenanthro[9,10-d]imidazoles. Different strategies have been developed for obtaining phenanthro[9,10-d]imidazoles, which enable modification of their optical properties upon interaction with specific analytes. These sensing responses usually involve changes in the fluorescence intensity and/or color arising from processes like photoinduced electron transfer, intramolecular charge transfer, intramolecular proton transfer in the excited state, and Förster resonance energy transfer. In this Review, we categorized these sensors into two different groups: those bearing formyl groups and their derivatives and those based on other molecular groups. The different optical responses of phenanthro[9,10-d]imidazole-based sensors upon interaction with specific analytes are discussed.

Cognitive Molecular Communication in Cylindrical Anomalous-Diffusive Channel

In this paper, an underlay cognitive molecular communication (MC) system with anomalous diffusion inside a blood-vessel like cylindrical channel is considered. We consider the presence of a primary and a secondary link in coexistence, with primary link having a higher priority for communication. To meet a certain quality of standard (QoS) at primary link, the interference due to the secondary is minimized by controlling the transmission at the secondary. The expressions for the concentration Green’s function (CGF) for anomalous diffusion and the number of molecules transmitted by the secondary transmitter are derived. The CGF is validated using the particle-based simulations. We analyze the channel performance in terms of probability of error, maximum achievable rate, receiver operating characteristics (ROC) and area under the curve (AUC). The decision threshold is optimized based on the log-likelihood ratio-test (LLRT) in order to minimize the probability of error. Furthermore, the effects of various parameters such as drift, diffusion, concentration degradation, channel radius and interference limit are analyzed. The derived expressions are validated through the Monte-Carlo simulations.

Limits of Parental Interference in a Child’s Personal Rights – Selected Issues

Abstract The article discusses the issues of the limits of parental interference in children’s personal rights. The conducted research covers the subject broadly. It starts with the general issues of legal capacity as the basis for the protection of subjective rights and then proceeds to demonstrating the lack of limitations in the protection of a child’s personal rights. A child growing up in a family remains under parental authority, which gives rise to certain obligations and rights of parents towards the child. Parents look after, educate and guide the child, carrying out their duties in the best interests of the child and guided by their good. It happens, however, that by caring for children, parents violate their personal rights. Therefore, the determinants of exercising parental authority were examined. Particular attention was paid to the scope of rights resulting from parental authority, the assessment of the manner of exercising it, the right of the child to express his or her own position and the principle of the best interests of the child. These determinants made it possible to indicate the limit of parental interference in the child’s personal rights. The practical side of the implementation of the right to the protection of a child’s personal rights was also indicated, as well as a proposal to amend the content of the family and guardianship code.

A novel approach to verifying and implementing a quantitative standard addition analysis of NPS drugs in forensic toxicology samples

The aim of this presentation is to describe the application of standard addition in forensic toxicology analysis for the rapid reporting of novel psychoactive substances (NPS). Standard addition is a quantitative analytical approach where the drug to be analyzed is fortified directly into aliquots of sample being tested, using the sample as its own matrix-matched control. The procedure can thus be used for quantitative determinations in multiple tissues and fluids. To achieve a quantitative result via standard addition, four replicate samples were aliquoted, three of which were fortified with the analyte of interest. All four samples were then extracted using liquid-liquid extraction with borax buffer (0.1 M, pH 10.4), and N-butyl chloride/ethyl acetate (70:30 v:v) as the extraction solvent. An analytical method for the compounds of interest was developed using a liquid chromatograph tandem mass spectrometer (Waters Xevo TQ-S micro). A method verification was performed on all standard addition methods with parameters adopted from the AAFS Standards Board (ASB) recommendations prior to testing authentic specimens. The method verification assessed linearity over the target range, limit of detection, recovery, and interference from matrix, analyte, internal standard, and commonly encountered drugs, as well as analysis of fortified control samples. Quantitative values were calculated by plotting the resulting analyte-internal standard peak area ratio (PAR) against the up-spike concentration, and a linear trendline between all data points was calculated. The concentration in the sample is determined by the x-intercept of the trendline with a correlation (R2) greater than 0.98. We have used the above approach to develop and validate methods for a variety of compounds in our laboratory to accelerate the process of reporting identifications and concentrations of new and emerging drugs. This allows us to support early dissemination of information and analytical data about new NPS compounds to laboratories, clinicians, and other stakeholders. This presentation describes its use for testing for N-pyrrolidino etonitazene (opioid), dimethylpentylone (stimulant), and 2-methyl AP-237/AP-238 (opioids). The linear dynamic range of N-pyrrolidino etonitazene and 2-methyl AP-237/AP-238 was evaluated from 0.1–100 ng/mL, and for dimethylpentylone it was evaluated from 1–500 ng/mL. No compounds demonstrated interferences for matrix, internal standard, analyte, or commonly encountered interferences. Recovery was also evaluated, and all analytes had a recovery of > 88%. Fortified control samples resulted in concentrations within ±20% of the target value. For dimethylpentylone, dilution studies were also performed; samples were diluted with water prior to the fortification with drug standards and demonstrated accurate quantitative values (±20%). Due to the tests being carried out within the matrix that is being tested, a larger sample volume is needed. Also, since standard addition involves testing each sample in replicates of four including the spikes, instrument capacity is increased, and costs are higher. The approach is best suited to less frequently encountered substances. Standard addition also requires some assumptions about the likely concentration of the substance that will be quantitated to determine what up-spike values are necessary. This can be done by evaluating the response of the analyte during our liquid chromatography quadrupole time of flight mass spectrometry screening analysis, and consideration of data of closely related drugs. With the everchanging and rapid turnover of the NPS market, standard addition may be the suitable choice for laboratories to report out a quantitative value without going through a costly comprehensive method validation. If a compound does become more prevalent such that standard addition is not appropriate for a long-term testing approach, standard addition can be a solution until validation of the complete method is completed. This would allow laboratories to provide toxicology data on NPS in a timelier manner to assist in making case interpretations.

Meshing theory of offsetting Archimedes cylindrical worm drive

The main purpose of this article is to establish the meshing theory for the offsetting Archimedes cylindrical worm drive, which consists of a cylindrical worm with asymmetric tooth profile and a plane worm gear. The equations of the tooth surfaces, the meshing function, the curvature interference limit function, and the curvature parameters are all obtained for the worm drive. By means of the developed reference-point-based meshing theory, the reference point located strictly on the tooth surfaces of a worm drive is determined via solving the system of nonlinear equations, in which no iteration is needed to perform this process. Based on the location of the reference point, the tooth surface boundaries are ascertained for the plane worm gear. The numerical case is carried out and the conjugate zone, the instantaneous contact lines, and the local meshing property parameters are acquired for the worm drive. The whole thread length of the cylindrical worm can almost be used and the conjugate zone can cover the whole tooth surface of the mating plane worm gear. In the meshing zone, not only the contact stress level between the tooth surfaces is relatively low, but also the lubrication condition is favorable. The comparative study on the meshing properties between the offsetting Archimedes cylindrical worm drive and the Archimedes conical worm drive is carried out.

A Surface Diffusion Barrier Strategy toward Water-Resistant Photonic Materials for Accurate Detection of Ethanol.

Photonic materials that enable visual detection of chemicals have shown great potential for wide applications in chemical, environmental, biotechnological, and food industries, but until now, using hydrophilic photonic materials for tracing water-soluble chemicals remains a major challenge due to the strong water interference. Here, we demonstrate a two-step co-assembly and subsequent surface coating strategy to develop an ethanol-sensitive and anti-water interference photonic crystal film. By using citric acid as a co-assembly phase, high ethanol sensing is realized because of the strong intermolecular affinity. By controlling the thickness of the outer polyvinyl butyral layer, selective ethanol penetration but a water barrier is enabled. Notably, the composite photonic films are free-standing, highly flexible, and controllably structurally colored. We further present using the composite film to quantitatively trace ethanol/water mixtures and potentially track drunk driving as a colorimetric sensor. The heuristic two-step modification strategy proposed in this work not only overcomes the limitation of water interference for hydrophilic colorimetric sensors but also provides references to develop more new photonic materials with water resistance that need to be applied in water/humid environments.

Seismic interpretation pitfalls caused by interference effects, exemplified by seismic modeling of outcropping chalk successions

Interference and inherent resolution limitations are well-recognized problems in reflection seismic data and have over time led to misinterpretations. Acquisition of seismic data containing a broad range of frequencies, including high frequencies, does not solve this problem but merely moves the problem to a finer scale. Forward seismic modeling of known geologic scenarios is a valuable tool for studying anticipated seismic responses of successions with a given set of geologic and/or rock physical characteristics and for predicting interpretational challenges. We perform finite-difference-based seismic forward modeling on a conceptual geologic model derived from outcropping chalk sections in southeast Denmark and evaluate possible pitfalls that may hamper interpretation of seismic data acquired from strata with similar characteristics. We demonstrate that interbedded strata with contrasting physical properties and variable thickness can result in interference effects resembling faults and fractures. The result has significance for characterization, e.g., geothermal sites, potential CO2 storage targets, groundwater reservoirs, and hydrocarbon exploration sites, in which the proper imaging of faults and fractures from seismic data is an essential task.

Optimal power allocation for non‐orthogonal multiple access enabled full‐duplex underlay cognitive relay networks under partial relay selection

AbstractThis article considers non‐orthogonal multiple access (NOMA) enabled full‐duplex (FD) underlay cognitive relay networks (ie, NOMA‐FDCRNs) with partial relay selection scheme. The secondary network, where NOMA is used, consists of a secondary base station (SBS) sending messages to two secondary users (SUs), that is, a near SU (SU1) and a far SU (SU2), by utilizing a dedicated relay selected from a set of FD decode‐and‐forward nodes. We obtain analytical expressions for the outage probabilities (OPs) of the SUs and then deduce the asymptotic OP expressions as well. Further, expressions are obtained for the optimal power allocation (OPA) coefficients at the SBS and at the relay that separately maximizes the throughput of the secondary network in NOMA‐FDCRN. Furthermore, the jointly optimal power allocation (JOPA) coefficients that maximize the throughput are also determined. The analyses consider (i) imperfect successive interference cancelation conditions, (ii) the tolerable interference limit of the primary receiver, (iii) the secondary nodes' maximum transmit power values, (iv) interference generated by the primary transmitter, and (v) the residual self‐interference (RSI) at the FD relay. It is shown that the proposed OPA coefficients at the SBS and the JOPA can mitigate the impact of RSI and significantly improve the OP and throughput performance. The numerical results show that the proposed JOPA approach provides 32% and 106% improvement of throughput compared to random power allocation (RPA) and equal power allocation (EPA) strategies, respectively. The OP of SU1 and SU2 reduce by 68% and 73%, respectively, under the proposed JOPA compared to RPA, while compared to EPA, the OP of SU1 and SU2 reduce by 96% and 97%, respectively.

Optimization method for spatial route adjustment of multi-bends pipes considering assembly demands

PurposeThis paper aims to propose an optimization method to automatically adjust the spatial route of multibend pipes to meet the assembly demands in constrained space.Design/methodology/approachThe compact geometric parameters that uniquely determine the pipe route are analyzed. Besides, the relationship between these parameters and the end pose is revealed based on the exponential product formula. Mathematical representations for the engineering constraints, including the end pose restriction, collision interference, manufacture ability and geometric limitations, are further established. On this basis, the adjustment of the spatial route is formulated as a multiconstraint optimization problem. A modified particle swarm optimization method based on the combination of gradient projection and swarm intelligence is designed to find the near-optimal pipe that meets the required assembly demands.FindingsThe experimental results show that the proposed method can effectively find the feasible pipe route that satisfies the engineering constraints and the end pose requirement is highly guaranteed.Originality/valueThe proposed method can automate the geometric adjustment of multi-bend pipes to meet the actual assembly demands, which significantly reduces manual efforts and guarantees high accuracy. The results demonstrate the possibility of further applications in the pipe assembly or design process, especially in ships, aerospace products or pressure vessels.