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The increasing usage of the Internet of Things (IoT) and other modern massive machine-type communication applications has led to a growing demand for more efficient u tilization o f a vailable c ommunication bandwidth. These applications necessitate the concurrent operation of multiple communication channels. The classical approach is Orthogonal Multiple Access (OMA), such as Time Division Multiple Access (TDMA) or Frequency Division Multiple Access (FDMA). However, an emerging alternative is Non-Orthogonal Multiple Access (NOMA), where communicating parties share one or more resources. The power domain NOMA scheme employs superposition coding (SC) and successive interference cancellation (SIC) to mitigate the effects of interference caused by overlapping frequency bands. Our proposal presents a partial NOMA solution: we retain the bandwidth division from the FDMA scheme but allow for partial overlap between neighboring channels. In this approach, we do not apply SIC; instead, we treat the interference caused by the overlap as part of the noise. This scheme enables the use of a wider bandwidth for individual channels. By carefully controlling the extent of overlap, we achieve a capacity increase resulting from the wider bandwidth that outweighs the capacity loss due to increased noise.

In this work, we propose a non-orthogonal multiple-relaxation-time (MRT) lattice Boltzmann method (LBM) for the two-dimensional (2D) incompressible Navier-Stokes equations in vorticity-stream function formulation. In this method, the vorticity and the streamfunction equations are calculated by two separate LB equations, which are constructed by using the non-orthogonal transformation matrix. Most importantly, to eliminate the residual term that may appear in the recovered vorticity equation, the convection term is handled as a source term in the LB equation rather than being directly recovered by the evolution equation. In addition, due to the convection term in our method is computed with a local scheme, it retains the parallel feature of the standard LBM. We then test the accuracy and the stability of the present LBM by considering various benchmark examples. The results show that the present method has a second-order convergence rate in space. Our numerical results indicate that the present LBM is a good candidate for solving streamfunction-vorticity formulation. • A MRT LBM is proposed for vorticity-streamfunction formulation. • The present model is constructed with a simple non-orthogonal matrix. • The convection term in vorticity equation is treated as a source in the LBE. [ABSTRACT FROM AUTHOR]

Current generation mobile communications require high-quality services. Adopting multiple access (MA) and multi-carrier waveforms potentially enhances the quality of services offered to end-users. However, in the majority of literature, the integration of multi-carrier and multiple-access approaches have not been extensively examined. One possible solution is to review multiple access and multi-carrier waveforms simultaneously to create a favorable foundation for the integration of these schemes. Thus, we consider a comprehensive review of multiple-access systems and multi-carrier waveforms jointly from $1^{st}$ to $5^{th}$ -generation (1G-5G) cellular networks. Initially, we present orthogonal MA (OMA) schemes called: frequency division multiple access (FDMA), time division multiple access (TDMA), code division multiple access (CDMA), and orthogonal frequency division multiple access (OFDMA) that have been utilized in 1G, 2G, 3G, and 4G, respectively. In addition, 5G wireless non-orthogonal multiple access (NOMA) techniques such as power domain NOMA (PD-NOMA), code domain NOMA (CD-NOMA), and other NOMA multiplexing methods are addressed in detail. On the other hand, we glanced at 5G cellular multi-carrier waveforms such as filter bank multi-carrier (FBMC), universal filtered multi-carrier (UFMC), generalized frequency division multiplexing (GFDM), and filtered orthogonal frequency division multiplexing (f-OFDM) waveforms. The assessment and comparison between different OMA, NOMA, and multi-carrier waveforms are carried out with the parameters: modulation schemes, bit error rate (BER), signal to noise ration (SNR), sum rate, peak-to-average power ratio (PAPR), latency, out of band emission (OOBE), and complexity. The analytical formulas of OMA, NOMA, and multi-carrier waveform schemes are also derived and verified using simulation data. Each multiple access strategy’s merits, shortcomings, applications, and factors influencing its performance are also addressed. Eventually, possible recommendations for the integration of multiple-access and modulation technologies for next-generation mobile networks are also included.

Spectral efficiency improvement is a key focus in most wireless communication systems and achieved by various means such as using large antenna arrays and/or advanced modulation schemes and signal formats. This work proposes to further improve spectral efficiency through combining non-orthogonal spectrally efficient frequency division multiplexing (SEFDM) systems with index modulation (IM), which can efficiently make use of the indices of activated subcarriers as communication information. Recent research has verified that IM may be used with SEFDM to alleviate inter-carrier interference (ICI) and improve error performance. This work proposes new SEFDM signal formats based on novel activation pattern designs, which limit the locations of activated subcarriers and enable a variable number of activated subcarriers in each SEFDM subblock. SEFDM-IM system designs are developed by jointly considering activation patterns, modulation schemes and signal waveform formats, with a set of solutions evaluated under different spectral efficiency scenarios. Detailed modelling of coded systems and simulation studies reveal that the proposed designs not only lead to better bit error rate (BER) but also lower peak-to-average power ratio (PAPR) and reduced computational complexity relative to other reported index-modulated systems. [ABSTRACT FROM AUTHOR]

A simultaneous wireless information and power transfer (SWIPT)-assisted cognitive overlay-based multiple input multiple output (MIMO) downlink (DL) cooperative relaying system has been considered wherein a secondary network comprising of an energy harvesting (EH) base station (BS) and possibly multiple fully wireless powered secondary users (SUs) share the spectrum of a primary network for information transmission and energy harvesting. In exchange, the secondary BS acts as a relay for the primary network and aids in transmitting information from the primary BS to the primary users (PUs) along with its own information using non-orthogonal transmission and the harvested energy. Closed-form expressions for the end-to-end outage probability (OP) at all the PUs and SUs have been obtained considering Rayleigh fading channel links and also sensitivity and saturation impairments at the energy harvesting nodes. Moreover, all the energy harvesting nodes have been assumed to be equipped with a finite battery for storing the harvested energy and rely solely on this stored energy for running the transceiver circuitry. Closed-form expressions have also been obtained to characterize the degradation due to the energy harvesting impairments and finite battery on the end-to-end OP of all the users. Furthermore, closed-form expressions for the asymptotic outage floor and diversity order have been obtained to analyze the performance of the system at high transmit power. Finally, simulation results have been presented to validate the analytical results derived and provide further insights into the performance of the system. [ABSTRACT FROM AUTHOR]

Electromagnetic waves carrying orbital angular momentum (OAM) can improve the spectral efficiency of communication systems by multiplexing a number of OAM modes. However, since being not able to perform water-filling power allocation and adaptive modulation for each sub-channel like closed-loop multiple-input multiple-output (MIMO) systems, the traditional orthogonal multi-mode OAM multiplexing system usually has poor bit error rate (BER) performance due to the inherent large divergence angle of high-order orthogonal OAM beams. Therefore, in this article we propose a non-orthogonal OAM (NO-OAM) multi-mode multiplexing scheme based on uniform circular array (UCA), which regulates the divergence angles of all non-orthogonal OAM beams to be the same, circumventing the problem that large beam divergence of high-order orthogonal OAM modes results in low received signal-to-noise ratio (SNR) at the receive UCA with a fixed aperture. Mathematical analysis and numerical simulations show that in contrast to the existing uniform concentric circular array (UCCA) beam adjustment scheme, the proposed NO-OAM scheme has slightly better beam adjustment effect but with only one UCA. Moreover, in contrast to the traditional orthogonal OAM multi-mode transmission, the proposed NO-OAM multi-mode multiplexing scheme has asymptotically equivalent channel capacity and much lower BER.

4 Results & discussion Figure 3 shows the temporal variation of the dimensionless equivalent equilibrium temperature ( HT ht , where HT ht is the temperature at film right edge (300 K), and HT ht is the temperature at film left edge (301 K)) at three different locations I A i , I B i , and I C i along the I x i -axis, which is also a line of symmetry for the geometry. [Extracted from the article]

Non-orthogonal multiple access (NOMA) technology meets the increasing demand for high-seed cellular networks such as 5G by offering more users to be accommodated at once in accessing the cellular and wireless network. Moreover, the current demand of cellular networks for enhanced user fairness, greater spectrum efficiency and improved sum capacity further increase the need for NOMA improvement. However, the incurred interference in implementing NOMA user grouping constitutes one of the major barriers in achieving high throughput in NOMA systems. Therefore, this paper presents a computationally lower user grouping approach based on discrete particle swarm intelligence in finding the best user-pairing for 5G NOMA networks and beyond. A discrete particle swarm optimization (DPSO) algorithm is designed and proposed as a promising scheme in performing the user-grouping mechanism. The performance of this proposed approach is measured and demonstrated to have comparable result against the existing state-of-the art approach. [ABSTRACT FROM AUTHOR]

According to the lumped mass method, this study presents a bending axial–torsional coupled dynamic model of a dual-branch transmission system with offset nonorthogonal spur (ONS) face gear pairs. The common form and force of the ONS face gear pair, the layout form of the dual-branch transmission system, and meshing phase differences are investigated in detail. The dynamic model considers factors, such as meshing phase differences, meshing stiffness, installation errors, damping, and elastic deformations. Results show that the dynamic uneven load of the system is affected by the meshing phase differences and gear vibrations when no installation error occurs. The input load and torsional stiffness have a crucial effect on the dynamic load sharing coefficients when installation errors exist. Moreover, the support stiffness of the spur cylindrical pinion 1 and the meshing stiffness fluctuation amplitude of each gear pair should be smaller. [ABSTRACT FROM AUTHOR]

In this paper, we propose the usage of Generalized Frequency Division Multiplexing (GFDM), a non-orthogonal multicarrier waveform for radar. We presented a novel method that cancels the effect of interference caused by the non-orthogonality of GFDM waveform in the radar processing, thus not affecting the performance of the radar. We show the viability of GFDM for radar with communications systems and the benefits of using it over Orthogonal Frequency Division Multiplexing (OFDM). Finally, we also present GFDM as a solution to mitigate inter-system interference in radar with communications (RadCom) systems, thus showing that GFDM may prove to be a better candidate than OFDM for RadCom applications. This method is validated with simulations and practical measurements at 24 GHz.

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The non-orthogonal bevel gear is the key component of a four-cylinder double-acting Stirling engine variable incline angle swashplate drive device,which can be used to support the torque of the inclined plate inclination in the angle adjustment of the inclined plate. In order to ensure the reliable and effective operation of the engine,the design of bevel gear and the analysis of fine strength are necessary. Based on this,in view of the high power four-cylinder double-acting Stirling swashplate engine,based on the variable angle of inclined plate transmission device layout requirements,the parameter design research of a Stirling engine nonorthogonal bevel gear transmission system is conducted,three-dimensional model of fine bevel gear contact strength analysis is established. Secondly,simulation analysis is carried out by using the finite element analysis software Workbench to verify the performance of the non-orthogonal bevel gear transmission system. On this basis,the influence of geometrical parameters on meshing properties of bevel gears is discussed. The results show that the maximum shape variables and the maximum stress of the gear are decreased with the increase of the tooth number in a certain range. This conclusion will provide certain theoretical basis for design and dynamic analysis for four-cylinder double-acting Stirling engine variable angle of inclined plate drive system optimization and performance improvement.

The debate of using zero padding (ZP) instead of a cyclic prefix (CP) for enhancing channel estimation and equalization performance is a recurring topic. This is particularly true for orthogonal signals, such as orthogonal frequency division multiplexing (OFDM). Yet, there are far fewer studies evaluating the impact of ZP and CP in non-orthogonal systems. Such systems have the added complexity of self-induced interference rendering channel estimation and equalization more challenging. For this reason, this work proposes a new channel estimation and equalization technique for non-orthogonal systems, which combines ZP with an orthogonal demodulator. Results show that the multipath components that appear in the ZP part can be used to enhance performance when compared to the CP approach. [ABSTRACT FROM AUTHOR]

Abstract A new framework, Eigen Analysis in General Curvilinear Coordinates (EAGCC), is presented for internal propagation of linear acoustic flow disturbances through irregular but smoothly varying duct geometries and non-uniform but smoothly varying mean flows. The framework is based on an eigen analysis of the linearised Euler equations for a perfect gas formulated in a general curvilinear coordinate system. A series of test cases are studied, from a simple uniform cylindrical annular duct with uniform mean flow to an axially and circumferentially non-uniform duct with non-uniform mean flow, which together validate the method for acoustic propagation through non-uniform annular ducts and non-uniform but irrotational and homentropic mean flow: although the framework provides for rotational and non-homentropic mean flow, and for modelling vortical and entropic flow perturbations, these features are not validated in this paper. Two propagation methods are presented. The first is a one-way "single sweep" calculation, in which only information travelling in the direction of propagation is retained. The second is an iterative "two-way sweep" method that accurately captures reflected waves and returns transmitted and reflected perturbations. Previous eigenvector analyses were subject to limitations on geometry and mean flow (for instance slowly-varying ducts) that are not required in the current method, for which the only limitations are that the duct and mean flow vary smoothly with position. This work extends the scope of the eigenvector approach to include acoustic problems previously limited to volumetric or surface-based methods. [ABSTRACT FROM AUTHOR]

Martdianto, R.; Muin, M.; Kusuma, S.B.; Muslim, A.B., and Alam, H.N., 2023. BOD-salinity simulation in the Sunter River Tanjung Priok port with a non-orthogonal model application. In: Lee, J.L.; Lee, H.; Min, B.I.; Chang, J.-I.; Cho, G.T.; Yoon, J.-S., and Lee, J. (eds.), Multidisciplinary Approaches to Coastal and Marine Management. Journal of Coastal Research, Special Issue No. 116, pp. 76-80. Charlotte (North Carolina), ISSN 0749-0208. Tanjung Priok port is the biggest port in Indonesia, located in the Capital City of Jakarta, equipped with two sides of a breakwater that protects the port from the direct impact of the sea. The Sunter river flow to Tanjung Priok port delivers high domestic waste as an influence of urban activities. The high content of BOD values along the Sunter river to Tanjung Priok increases the source of water pollution that needs to control correctly. Tanjung Priok also has pollution sources consisting of solid domestic waste, domestic liquid waste, and oil sludge. The Sunter river streamflow in the Jakarta drainage system is divided by Kanal Banjir Timur (KBT), changing flow rate, and water quality pattern. The study area is the Sunter river's main channel, which has a 17 km length and includes Duren Sawit, Pulo Gadung, Kelapa Gading, Plumpang, Rawa Badak, and Tanjung Priok. To describe the complexity of a river's geometric flow to an estuary along the Sunter river to Tanjung Priok, the concept of a curvilinear Non-Orthogonal model is used, which is careful in composing the river morphology shape, river-channel branching, dimension, and elevation of the river to the estuary. Efforts to improve water quality along the Sunter river by increasing saltwater's effect by carrying out a Density-Induced Current (DIC) and dredging configuration. Dredging at the mouths of rivers by considering the influence of DIC involves water currents, river flow, wind stress, and tides. The study presents several simulation scenarios using MuQual3D to assess water quality problems in the Sunter river by increasing salinity through river dredging. [ABSTRACT FROM AUTHOR]

• The effective kinematic model of non-orthogonal theodolite is established. • The accurate expression of the laser axis pose error in arbitrarily motion state is proposed. • The aiming error is defined and used as the key reference parameters for error identification. • Shafting error parameters identification is achieved without actual reference end on laser axis. • Shafting error compensation by iteration is achieved and verified. The research about non-orthogonal shafting laser theodolite (N-theodolite) is motivated by the growing demand for instrument. The reference pose of laser axis in motion state cannot be obtained due to the absence of reference end, and the error compensation of the N-theodolite is lack of basis. Therefore, the shafting error parameters identification and compensation method without reference end is proposed in this paper. Based on the derived kinematics model of the N-theodolite, the laser axis pose error in motion state can be described accurately. Then the aiming error is defined as the key reference parameters to construct the linear equations for effective identification and iterative compensation of shafting error. The experimental results have shown that the average aiming error of the compensated N-theodolite is less than 0.04 mm within 10 m. Compared with the existing calibration approaches, the shafting parameters adjustment performance of the proposed method is more prominent. [ABSTRACT FROM AUTHOR]

A novel cost-effective non-contact 3D measurement system is proposed in this paper, which consists of two rotary tables and one laser range finder. No orthogonal accuracy between the three axes (two rotation axes and the laser axis) is required, i.e. the three parts of the sensor unit (two rotary tables and the laser range finder) need not be assembled orthogonally, which lowers the barrier to manufacture it. Time for adjustment and recalibration with non-orthogonality is also saved, compared to traditional instrument. A computing algorithm is proposed for the system to measure all the points in the measurement space, and the experiments validate that the proposed system is able to deliver relevant performance for indoor and outdoor construction measurement. [ABSTRACT FROM AUTHOR]

• A 3D fracture model was developed to simulate the interactions between fracture and oblique bedding plane. • A good match of width profile was shown between the developed fracture model and Abaqus simulator. • Width profiles and shear sliding were analyzed under the influence of different controlling parameters. • Fracture width at the junction area was calculated to provide a critical insight of selecting a proper proppant. • Positive correlation between approach angle and shear sliding was consistent with other numerical experiments. Weak bedding planes (interfaces), a critical factor in determining the fracture height growth and the propagation pathway of the fractures, is pervasively distributed in the unconventional reservoirs. In the real world, multi-layered bedding planes, regarded as frictional discontinuities, are not horizontally distributed in the formation. In this paper, a three-dimensional fracture model, based on the three-dimensional displacement discontinuity method, was developed to simulate the interactions between vertical/slanted hydraulic fractures and frictional discontinuities (such as natural fractures or horizontal/oblique bedding plane segments) with non-orthogonal approach angle. Comparison of width profiles between the developed fracture model and Abaqus simulator showed a good agreement. In the case studies, width profiles and shear displacement discontinuity along the interface were analyzed under the influence of approach angle, ratio of distance between the injection source and interface to the fracture height, fluid pressure, Young's modulus and Poisson's ratio. A positive relation exists between shear sliding along the interface and approach angle, which conforms to the numerical experiments from the three-dimensional Discrete Element Method model. Interface location from the injection source has unconspicuous impact on the interface opening and shear sliding along the interface with non-orthogonal approach angle. The increment of fluid pressure makes alteration of vertical fracture more apparently in the non-orthogonal case. Smaller Young's modulus makes the interface easier to be opened in the orthogonal case. This model enables to calculate fracture width distribution at the intersection area, which provides a guideline for proppant transport and avoid potential bridging and screen-out of the proppant. [ABSTRACT FROM AUTHOR]

With the development of 5G communication, the new non-orthogonal multi-carrier transmission technology has been paid more attention. A filtering operation is made on a group of continuous subcarriers in Universal-filtered multi-carrier (UFMC), making the orthogonality among the subcarriers no longer exist. Such feature has relaxed the strict constraint of synchronization between the various devices, and makes it more suitable for the needs of 5G. On the other hand, the non orthogonality causes the mutual interference among the subcarriers and sub-bands. If the interference is effectively reduced, the performance of UFMC can be improved. In this paper, the factor of true power ratio is proposed to evaluate the inter-band interference. Furthermore, with the specific filter parameters, an appropriate sub-band interval can reduce the energy interference between the sub-bands especially in the uplinks. Simulation result shows that the method can reduce the symbol error rate and improve the transmission performance of UFMC by deploying the sub-band with optimized interval. Especially in high SNR environment, the deployment of shorter filter and neighboring sub-bands shows a better performance. [ABSTRACT FROM AUTHOR]

We compare theoretically the effects of channel decoherence on entangled coherent states (ECSs) and entangled squeezed states (ESSs) as non-orthogonal states. The comparison is achieved in the case when the interaction with the noisy environment is symmetric and when it is asymmetric. In the first case, we notice a robustness of ECSs compared with ESSs against the photons losses. This robustness increases with a good way after using a higher amplitudes. However, in the asymmetric decoherence case, the ESSs resist more the photon losses compared with the ECSs. [ABSTRACT FROM AUTHOR]

REVO five-axis system, designed for the orthogonal coordinate measuring machines, must be reconfigured for the application in the non-orthogonal coordinate measuring machines. First, in this article, error sources of the system and components of measurement data are analyzed; then, scale values of coordinate measuring machine axes, which are essential to derive the coordinates of measured points in non-orthogonal coordinate measuring machine, are separated out. Besides, the mathematical model of REVO is established based on the quasi-rigid body theory, from which the measurement results can be evaluated by data derived instead of that returned by the system. The effectiveness of both separation of scale values and mathematical model of REVO is proved by experiments and practice. The research of this article is of great significance to the application of REVO five-axis system in the non-orthogonal coordinate measuring machine. [ABSTRACT FROM AUTHOR]

In this paper, a non-orthogonal multiple-relaxation-time (MRT) lattice Boltzmann (LB) method for simulating incompressible thermal flows is presented. In the method, the incompressible Navier–Stokes equations and temperature equation are solved separately by two different MRT-LB equations, which are developed based on non-orthogonal basis vectors obtained from the combinations of the lattice velocity components. The macroscopic governing equations of incompressible thermal flows can be recovered from the method through the Chapman–Enskog analysis in the incompressible limit. Numerical simulations of several typical two-dimensional problems are carried out to validate the proposed method. It is found that the present results are in good agreement with the analytical solutions and/or other numerical results reported in the literature. Furthermore, the non-orthogonal MRT-LB model shows better numerical stability in comparison with the BGK-LB model, and the grid convergence tests indicate that the present MRT-LB method has a second-order convergence rate in space. [ABSTRACT FROM AUTHOR]

It is shown that the system of unit vectors corresponding to the internal coordinates is non-orthogonal generally. The deduction starts with the well-known orthonormality of unit vectors of the Cartesian coordinates. The crucial point of the GDIIS method is discussed regarding a "partially isomorphic" relationship between two vector spaces. Some features of the pseudoinverse of the Eliashevich–Wilsonian matrix B are deduced and discussed: these are analogous to the conditions formulated originally for the elements of the B-matrix. [ABSTRACT FROM AUTHOR]