Imperfect Conditions Research Articles

A User Pairing Algorithm for the Uplink NOMA With Imperfect CSI

ABSTRACTIn this paper, the problem of user pairing across subcarriers is investigated for the uplink non‐orthogonal multiple‐access (NOMA) systems, in which every subcarrier is assigned to exactly two users. Considering fixed transmit power for all users, we pair users such that sum‐rate is maximized over all subcarriers. While different (near) optimum allocation schemes exist in the literature, they pertain to perfect channel state information (CSI), which is impractical. To overcome this limitation, we assume statistical CSI is available in the form of the first two moments of channel gains. Then, we maximize a lower bound on the sum rate over user pairings utilizing a block coordinate ascent (BCA) approach with guaranteed convergence to a suboptimal solution. Numerical results corroborate a satisfactory performance for our proposed algorithm versus the perfect CSI benchmark and a simple random assignment approach. For high signal to noise ratios (SNRs) and the more challenging frequency selective fading setup, the solution of our proposed algorithm comes close to those of the optimal pairing with perfect CSI. Furthermore, simulations revealed that if the proposed BCA is utilized assuming perfect CSI, it performs similar to the well‐known global optimum in the frequency flat fading setup and outperforms the best existing near‐optimal solution in the frequency selective fading scenario. These observations offer a testament to the strength of the proposed BCA algorithm in both perfect and imperfect CSI conditions.

Effect of imperfect boundary conditions on free vibrations of square simply supported plates

ABSTRACT In this research, the influence of clearance of supports on free vibrations of a simply supported square plate has been analysed and investigated. To achieve this objective, the boundary conditions in clearance supports are assumed to be non-ideal and the vibration equations of the plate are examined by Lindstedt-Poincaré perturbation technique. For the validation of the performed solution and the obtained results, in a special case of one non-ideal boundary, condition, the dimensionless non-ideal natural frequencies were compared with reference. Eventually, a square plate which simply supported with two non-ideal boundary conditions on two opposite edges has been investigated. The existence of the opposite non-ideal boundary conditions, causes symmetry in the mode shapes of the plate. Based on the results, in general with going up the clearance, the difference between ideal and non-ideal natural frequencies rises as well.

Dispersive and attenuation behavior of Love wave in a non-local highly heterogeneous media with imperfect contact condition

Abstract The primary aim of this study is to explore the impact of different physical parameters on the propagation of Love waves in non-local media. This study considers heterogeneous orthotropic viscoelastic properties within a layer and the variation of sandy medium properties with exponential depth, representing the half-space. Furthermore, the interface between the layer and the half-space is considered mechanically imperfect and perfect. The solutions of mechanical displacement of the layer and half-space are derived separately by solving the second-order hyperbolic type differential equation with the help of a variable-separable technique. A closed form of the dispersion relation is obtained using appropriate boundary conditions involving the medium's non-local elasticity and inhomogeneity parameters. Verification of the dispersion relation is shown by deriving some particular cases and comparing them with the classical dispersion relation of Love wave. The effects of physical parameters (like viscoelasticity, inhomogeneity, interfacial imperfection, sandy, non-locality, and \textcolor{blue}{thickness of the layer}) on the phase and attenuation phenomena of Love wave are investigated through numerical calculations and graphical representation. Furthermore, it is observed that the particle displacement in the layer decreases with depth, while in the half-space, the amplitude decreases oscillatory with depth, and the displacement gradually converges towards zero. A comparative graphical analysis of these parameters on the phase and attenuation characteristics of Love wave through the stratified Earth's structure with imperfect and perfect interfaces has been accomplished.

Analytical formulae for the higher-order effective coefficients of periodic laminated elastic composites with imperfect contact

Analytical formulae are derived for the effective coefficients of linear elastic second-order laminate composite materials made of any finite number of linear elastic first-order layers. Imperfect contact conditions are considered at the interfaces, and small strains are assumed at the micro and macro scales. The “micro-macro” homogenization procedure used here is reported in Continuum Mech. Thermodyn. (2020) 32:1251-1270 wherein only numerical studies are presented. Asymptotic homogenization method results at the micro-scale level are combined with the macro-scale parameters based on the equivalence of the stored energies on the periodic cell (i.e., the energy-averaging theorem known as the Hill-Mandel condition). Some comparisons are considered for validation. To the best of our knowledge, the fully analytical application of this methodology to the case of laminate media has not been reported previously, that is, with the analytical solution of the local problems. The formulas obtained could be useful to control numerical codes in more complex periodic cells. Projects PAPIIT DGAPA UNAM IN101822, Mexico, and CNPq Universal Nº 402857/2021-6, Brazil, are gratefully acknowledged. CAPES Brazil Program (PRAPG) – Edital No 14/2023 is also recognized.

Financial market structure and capital controls in Sub-Saharan Africa

PurposeThis study investigates the influence of capital controls on financial market structure in Sub-Saharan Africa (SSA). This is especially relevant as the former restrictions are relatively common on the sub-continent. At the same time, the sub-region’s financial markets are highly bank-based and focused on the short term, with stock markets being illiquid and stunted.Design/methodology/approachTo achieve its research objectives, the study posits an original model and uses comparative statics to analyze the relation between the aforestated phenomena in a representative SSA economy. Key hypothesized conclusions derived therefrom are tested using panel econometrics.FindingsThe comparative static analysis illustrates that capital controls favor banks, making them monopolistic and inefficient. This is confirmed by the empirical investigation, as the said market restriction skews financial market structure towards a bank-dominated system.Research limitations/implicationsThe study limits itself to capital controls and their effects on financial market structure. It does not particularly investigate the influence of different types of these restrictions. Specifically, it dichotomizes the influence of the examined controls on bank and stock markets.Practical implicationsThe dissimilar influence of capital controls on banks relative to stock markets is critical for decision and policymakers. This paper highlights that capital controls may have unintended adverse effects on domestic financial markets. Also, they may not be the most appropriate policy to deepen markets and enhance domestic resource retention. There is, consequently, a need to determine fitting policies that attract rather than repel financial flows. Furthermore, capital controls may engender rather than address macroeconomic misalignment.Social implicationsAs a social imperative, it is necessary to analyze SSA’s framework of capital restrictions to better understand how they distort market incentives and mechanisms. This would help identify adverse effects that retard social development.Originality/valueThis study extends existing literature by developing a novel analytical framework incorporating key characteristics of SSA economies. This helps to better understand the nature of the capital controls–financial market structure relation in imperfect market conditions.

Deep Learning-Enhanced Autoencoder for Multi-Carrier Wireless Systems

In a multi-carrier (MC) system, the transmitted data are split across several sub-carriers as a crucial approach for achieving high data rates, reliability, and spectral efficiency. Deep learning (DL) enhances MC systems by improving signal representation, leading to more efficient data transmission and reduced bit error rates. In this paper, we propose an MC system supported by DL for operation on fading channels. Deep neural networks are utilized to model the modulation block, while a gated recurrent unit (GRU) network is used to model the demodulation blocks, acting as the encoder and decoder within an autoencoder (AE) architecture. The proposed scheme, known as MC-AE, differs from existing AE-based systems by directly processing channel state information and the received signal in a fully data-driven way, unlike traditional methods that rely on channel equalizers. This approach enables MC-AE to improve diversity and coding gains in fading channels by simultaneously optimizing the encoder and decoder. In this experiment, we evaluated the performance of the proposed model under both perfect and imperfect channel conditions and compared it with other models. Additionally, we assessed the performance of the MC-AE system against index modulation-based MC systems. The results demonstrate that the GRU-based MC-AE system outperforms the others.

Transverse squeeze flow of thermoplastic composite tape during in-situ consolidation via automated fiber placement

Transverse squeezing of thermoplastic composite tapes during automated fiber placement is a challenge in controlling gaps/overlaps of adjacent bands. A theoretical model may provide insights on direct effect of process parameters on deformation of tape. The developed models in this work evaluate non-Newtonian squeeze flow of molten tape using power-law viscosity under three different no slip, perfect slip, and imperfect slip boundary conditions at interface during in-situ consolidation, aiming to predict the final width of tape with minimal computational costs. The results predicted by models are verified using finite element analysis with close agreement. Subsequently, no slip and perfect slip assumptions underestimated and overestimated the experimental measurements of consolidated widths, respectively. However, the squeeze model with imperfect slip condition may effectively capture the trends in the experimental data. This model includes the effect of intimate contact development on the friction parameter during squeezing, utilizing a new non-Newtonian trapezoidal asperity model.

A Co-Location Study of 87 Low-Cost Environmental Monitors: Assessing Outliers, Variability, and Uncertainty

While field research in indoor air quality (IAQ) increasingly uses large numbers of low-cost sensors, detailed validation of each sensor is becoming infeasible, ignored, or undeclared. Questions remain about whether these sensors meet manufacturer or third-party specifications and whether their utility improves with some validation, even under imperfect conditions. This study details the outcomes of a co-location experiment with 87 low-cost IAQ monitors, conducted with the objective of verifying their performance in measuring total volatile organic compounds (tVOCs), particulate matter 2.5 (PM2.5), carbon dioxide (CO2), temperature, and relative humidity. The monitors were installed next to professional-grade reference IAQ instruments in an office with controlled ventilation. A mixed validation methodology was used, involving outlier detection, uncertainty quantification, and performance metric calculations. Results showed that CO2, temperature, and humidity sensors reliably met manufacturer specifications, while tVOC sensors had significant accuracy issues, deviating by up to 79% from reference measurements—substantially more than the stated uncertainty of ±20%. PM2.5 sensors were more consistent but had an error margin of ±27%, compared to the stated ±15%. A total of 5 of the 87 sensors (5.7%) were outliers for at least one IAQ indicator. Despite the need for further long-term validation, this study highlights the importance of performing an experimental evaluation of low-cost IAQ monitors before field deployment.

Quantum-enhanced mean value estimation via adaptive measurement

Quantum-enhanced (i.e., higher performance by quantum effects than any classical methods) mean value estimation of observables is a fundamental task in various quantum technologies; in particular, it is an essential subroutine in quantum computing algorithms. Notably, the quantum estimation theory identifies the ultimate precision of such an estimator, which is referred to as the quantum Cramér-Rao (QCR) lower bound or equivalently the inverse of the quantum Fisher information. Because the estimation precision directly determines the performance of those quantum technological systems, it is highly demanded to develop a generic and practically implementable estimation method that achieves the QCR bound. Under imperfect conditions, however, such an ultimate and implementable estimator for quantum mean values has not been developed. In this paper, we propose a quantum-enhanced mean value estimation method in a depolarizing noisy environment that asymptotically achieves the QCR bound in the limit of a large number of qubits. To approach the QCR bound in a practical setting, the method adaptively optimizes the amplitude amplification and a specific measurement that can be implemented without any knowledge of state preparation. We provide a rigorous analysis for the statistical properties of the proposed adaptive estimator such as consistency and asymptotic normality. Furthermore, several numerical simulations are provided to demonstrate the effectiveness of the method, particularly showing that the estimator needs only a modest number of measurements to almost saturate the QCR bound.

A Multi-Strategy Hybrid Sparse Reconstruction Method Based on Spatial-Temporal Sparse Wave Number Analysis for Enhancing Pipe Ultrasonic-Guided Wave Anomaly Imaging.

Ultrasonic-guided waves (UGWs) in defective pipes are subject to severe coherent noise caused by imperfect detection conditions, mode conversion, and intrinsic characteristics (dispersion and multiple modes), inducing the limited performance of anomaly imaging. To achieve the high resolution and accuracy of anomaly imaging, a multi-strategy hybrid sparse reconstruction (MHSR) method based on spatial-temporal sparse wavenumber analysis (ST-SWA) is proposed. MHSR leverages the capability of ST-SWA to extract the wavenumber dispersion curves, thereby providing a more refined and precise search space for MHSR. Furthermore, it mitigates the impact of coherent noise by conducting dispersion compensation on the reconstructed signal. The sparse compensated signals through MHSR are employed for sparse reconstruction imaging. To validate the efficacy of the proposed method, UGW testing is performed on the defective steel pipe, and the results demonstrate the significant enhancement of anomaly imaging in defect resolution and positioning accuracy. The lowest estimated errors for axial and circumferential defect positions are 10 mm and 4 mm, respectively.

"What choice do we have?" Reactive and proactive decision-making for aging in place with dementia.

Promoting options for aging in place (AIP) has broad appeal to policymakers and professionals providing services to persons living with dementia (PWD). However, the benefits or burdens of AIP likely vary among individuals and families. We sought to describe factors influencing decision-making to age in place versus seek a higher level of residential care for PWD. A qualitative study was undertaken as part of a larger mixed-methods study utilizing semi-structured interviews with PWD, family care partners, and dementia clinicians. Interview transcripts were analyzed using qualitative content analysis with constant comparison. Sample size was determined by thematic saturation within subgroups. We conducted 74 interviews among 14 PWD, 36 care partners, and 24 clinicians. Preferences for AIP were driven by (1) desire to preserve independence, (2) a sense that the "best care" is delivered by loved ones and in a familiar environment, (3) distrust and fear of care facilities, and (4) caregiver guilt. PWD and care partners frequently considered moving from home as a "last resort" and wanted to avoid planning for future care needs. Many decisions to move were reactive and triggered by patient safety events, physical dependency, or the loss of caregiver. Proactive decision-making was facilitated by (1) prior experience witnessing the challenges of caring for a person with advanced dementia in the home; and (2) having substantial financial resources such that participants could seek major home adaptations or avoid "lower quality" institutions. Decisions regarding care setting for PWD frequently do not feel like a choice and are made under imperfect conditions. Programs using AIP as an outcome measure should recognize the various patient-centered and non-patient-centered factors that influence such choices, and interventions should be designed to promote more informed and equitable decision-making for care setting in dementia.

Enhanced Energy Transfer Efficiency for IoT-Enabled Cyber-Physical Systems in 6G Edge Networks with WPT-MIMO-NOMA

The integration of wireless power transfer (WPT) with massive multiple-input multiple-output (MIMO) non-orthogonal multiple access (NOMA) networks can provide operational capabilities to energy-constrained Internet of Things (IoT) devices in cyber-physical systems such as smart autonomous vehicles. However, during downlink WPT, co-channel interference (CCI) can limit the energy efficiency (EE) gains in such systems. This paper proposes a user equipment (UE)–base station (BS) connection model to assign each UE to a single BS for WPT to mitigate CCI. An energy-efficient resource allocation scheme is developed that integrates the UE–BS connection approach with joint optimization of power control, time allocation, antenna selection, and subcarrier assignment. The proposed scheme improves EE by 24.72% and 33.76% under perfect and imperfect CSI conditions, respectively, compared to a benchmark scheme without UE–BS connections. The scheme requires fewer BS antennas to maximize EE and the distributed algorithm exhibits fast convergence. Furthermore, UE–BS connections’ impact on EE provided significant gains. Dedicated links improve EE by 24.72% (perfect CSI) and 33.76% (imperfect CSI) over standard connections. Imperfect CSI reduces EE, with the proposed scheme outperforming by 6.97% to 12.75% across error rates. More antennas enhance EE, with improvements of up to 123.12% (conventional MIMO) and 38.14% (massive MIMO) over standard setups. Larger convergence parameters improve convergence, achieving EE gains of 7.09% to 11.31% over the baseline with different convergence rates. The findings validate the effectiveness of the proposed techniques in improving WPT efficiency and EE in wireless-powered MIMO–NOMA networks.

Maiolica seen by Vis–NIR hyperspectral imaging spectroscopy: the application of an ultraportable camera at the Museo Nazionale del Bargello

An ultraportable hyperspectral camera operating in the Vis–NIR range (400–1000 nm) was used in this study for the non-invasive analysis of a selection of Italian maiolica wares and sherds from the Museo Nazionale del Bargello in Florence, Italy. The studied objects included authentic archaeological sherds, nineteenth-century forgeries, and ceramics of uncertain origin. The primary aim of this study was to evaluate the efficacy of hyperspectral imaging (HSI) spectroscopy combined with multivariate analysis for examining highly refractive and three-dimensional glazed ceramic artefacts within the constraints of a museum environment, including imperfect lighting conditions. Two data processing pipelines were tested: one based on principal component analysis (PCA) with score plots and the other on spectral angle mapper (SAM) classification obtained through the ENVI Spectral Hourglass Wizard (ENVI-SHW). The analyses enabled the discrimination between original parts and/or restored parts and additions. Among others, a complex assemblage of original sherds, restored parts, and non-ceramic parts was observed in a Renaissance pastiche vase. Furthermore, the method enabled the identification of the various chromophores providing clues on the artistic colour palette. In particular, the identification of chromium in the blue and green glazes of two objects of uncertain chronology suggested that they were not made before the nineteenth century. The acquisition of a larger and more detailed database of HSI data on maiolica glazes is strongly encouraged to improve the applicability of this method in authenticity, art-historical and archaeological studies.

Toward occupant-centric system: Multicriteria optimization of hybrid displacement–personalized ventilation system using computational fluid dynamics with computer-simulated person

Engineers have integrated general ventilation systems with personalized ventilation (PV) to achieve energy efficiency while providing good indoor air quality (IAQ) and thermal comfort. Previous studies conducted parametric analyses of PV by varying its flow rate and temperature, analyzing energy, IAQ, and thermal comfort while keeping main ventilation settings constant, even though the latter significantly affect the general flow field. Therefore, computational fluid dynamics simulation is performed to simultaneously optimize the above-mentioned three outputs in an office with displacement ventilation (DV) and PV by varying the DV supply flow rate and temperature, the fraction of outlet air being resupplied to inlet or DV recirculation, and PV supply flow rate and temperature. We utilize the Taguchi design to minimize the number of simulations as well as use the “technique for order preference by similarity to ideal solution” (TOPSIS) coupled with Taguchi's signal-to-noise ratio analysis for optimization. Four optimization cases are investigated by varying the thermal comfort and IAQ parameters from volume-averaged to occupant-centric values, such as the skin temperature and inhaled concentration. Results show that occupant-centric optimization presents low energy requirements with acceptable IAQ and thermal comfort compared with volume-averaged optimization, which can be attributed to imperfect mixing conditions. Furthermore, the DV settings and thermal plumes significantly affect the direction of jet released by the PV, which does not improve the IAQ. This underscores the importance of considering the aforementioned effects in maximizing the PV potential. Nevertheless, the PV system functions as intended under a flow rate of 6 L/s.

The Effect of Optimism and Gratitude on Subjective Well-Being of Parents of Children with Special Needs

The children who are born with imperfect conditions are often referred as children with special needs. Parents of children with special needs shown to have low levels of optimism and gratitude, which can affect the level of subjective well-being. This research aims to prove the influence of optimism and gratitude on the subjective well-being of parents with special needs children. The present study used a quantitative approach with a survey research type. The research location was in Pidie Regency, Aceh, with a sample size of 132 parents aged 20-55. The sampling technique used simple random sampling. The instruments used in this research include The Satisfaction of Life Scale (SWLS) and Scale of Positive and Negative Experience (SPANE) with a reliability value of 0.710, the Revised Life Orientation Test (LOT-R) with a reliability value of 0.793, and the Gratitude Questionnaire (Q-6) with a reliability value of 0.761. The result shows that optimism and gratitude can simultaneously influence the subjective well-being of parents who have children with special needs (ß=0.087, p=0.000). The practical contribution made by optimism and gratitude to subjective well-being is 97.5%. The study revealed that optimism and gratitude are very influential in increasing subjective well-being in parents. In conclusion, parents with high subjective well-being tend to show confidence, appreciation, and satisfaction in life, thus positively contributing to parental involvement with children.

Performance Analysis of Distributed Reconfigurable-Intelligent-Surface-Assisted Air–Ground Fusion Networks with Non-Ideal Environments

This paper investigates the impact of non-ideal environmental factors, including hardware impairments, random user distributions, and imperfect channel conditions, on the performance of distributed reconfigurable intelligent surface (RIS)-assisted air–ground fusion networks. Using an unmanned aerial vehicle (UAV) as an aerial base station, performance metrics such as the outage probability, ergodic rate, and energy efficiency are analyzed with Nakagami-m fading channels. To highlight the superiority of RIS-assisted air–ground networks, comparisons are made with point-to-point links, amplify-and-forward (AF) relay scenarios, conventional centralized RIS deployment, and fusion networks without hardware impairments. Monte Carlo simulations are employed to validate theoretical analyses, demonstrating that in non-ideal environmental conditions, distributed RIS-assisted air–ground fusion networks outperform benchmark scenarios. This model offers some insights into the improvement of wireless communication networks in emerging smart cities.

Extracting building outlines based on convolutional neural networks using the property of linear connectivity

Abstract. For years, researchers have been developing an automated method that can replace humans by drawing the outlines of individual buildings in a vector format, which plays an important role in GIS creation, environmental monitoring, urban planning, population density estimation, and energy supply. There is no doubt that this is an extremely difficult task, not only because of the labor required to develop such a highly intelligent algorithm, but also because of the challenges posed by imperfect imaging conditions, different building structures, and the complexity of the background. One of the current challenges in extracting building outlines is to accurately recreate the polygonal boundaries of the building while extracting vectorized building masks as output for direct use in various applications. This work provides a comprehensive workflow for building extraction and improves the predicted area of buildings through boundary regularization. First, a convolutional neural network is used to train instance segmentation model, then regularization and vectorization processes are performed. The main difference from existing methods is a new regularization method based on the concepts of linear connectivity and convexity of a set of points. This approach can effectively identify and remove points that do not belong to the detected building but were incorrectly segmented by the algorithm. Based on the results of experiments, the algorithm showed a high level of efficiency, comparable to leading methods for extracting building boundaries as PolyWorld.

Optimizing secure power allocation in massive MIMO systems with an eavesdropper under imperfect CSI conditions

Optimizing secure power allocation in massive MIMO systems with an eavesdropper under imperfect CSI conditions

Multi-robot social-aware cooperative planning in pedestrian environments using attention-based actor-critic

Safe and efficient cooperative planning of multiple robots in pedestrian participation environments is promising for applications. In this paper, a novel multi-robot social-aware efficient cooperative planner on the basis of off-policy multi-agent reinforcement learning (MARL) under partial dimension-varying observation and imperfect perception conditions is proposed. We adopt a temporal-spatial graph (TSG)-based social encoder to better extract the importance of social relations between each robot and the pedestrians in its field of view (FOV). Also, we introduce a K-step lookahead reward setting in the multi-robot RL framework to avoid aggressive, intrusive, short-sighted, and unnatural motion decisions generated by robots. Moreover, we improve the traditional centralized critic network with a multi-head global attention module to better aggregate local observation information among different robots to guide the process of the individual policy update. Finally, multi-group experimental results verify the effectiveness of the proposed cooperative motion planner.

Strategic planning as an element of management of the development of the pension system of the Russian Federation

The object of the study is the pension system of the Russian Federation, the subject is the long–term strategic planning for the development of the national pension system. The purpose of the research is to develop proposals for improving the strategic planning of the development of the pension system of the Russian Federation. Special attention is paid to the structure and key provisions of the Strategy for the Long-term Development of the Pension System of the Russian Federation until 2030 (the "Strategy"), the possibility of assessing its implementation, the comparability of the parameters of the functioning of the Russian pension system and data from the long-term budget forecast and forecasts of socio-economic development of the Russian Federation, the interconnection of the goals and objectives of the Strategy and national development goals of the Russian Federation, which makes it possible to develop and implement a comprehensive and coordinated state policy in the field of pension provision for the population. The author considers the expediency of maintaining the current high-level goals of the Strategy in the context of modern socio-economic parameters and trends in the functioning of the Russian economy. The author proceeds to systematization and comparison of the provisions of normative legal acts that are strategic planning documents, modeling of the volume of pension rights, coefficient, graphical, comparative, vertical and horizontal analysis of pension provision indicators. In the course of the study, it was found that the strategy is being implemented in conditions of imperfection of strategic planning documents in terms of pension provision, characterized by low reliability of forecasts, outdated terminology and weak alignment of medium- and long-term planning documents in terms of goal setting, forecasting and programming, weak alignment with the national development goals of the Russian Federation until 2030 and for the future until 2036 the year, the lack of program-oriented cost management in the compulsory pension insurance system. The strategy does not contain unambiguously interpreted indicators of its implementation, does not take into account a significant change in the macroeconomic situation, the transition to a point pension formula, does not contain an assessment of the risks of its implementation, and indicators of the implementation of many of its tasks are not disclosed in other types of strategic documents. We have proposed a number of principles for developing a long-term plan for the development of the pension system, including risk assessment, internal stabilizers and a phased breakdown of the values of indicators of its implementation, as well as defined guidelines for its long-term development, including limiting the growth of the share of the budget mechanism in the national pension system.