Complementary Function Research Articles

Synthesis of High-Selectivity Two-Dimensional Filter Banks Using Sigmoidal Function

This paper explores an application of the sigmoidal function—the complementary integral Gaussian error function (erfc(.))—in two-dimensional (2D) uniform and nonuniform filter bank synthesis. The complementary integral Gaussian error function graph represents a smooth low-pass filter magnitude response. A parameter changes the function slope and increases the magnitude response selectivity. The theory is applied to 2D band-pass filter banks. Exact expressions for the magnitude response parameters are determined. As a result, 2D uniform and nonuniform filter banks with very high selectivity and exact shapes are obtained. Three synthesis examples of 2D filter banks with circular and fan-shaped magnitude responses are provided. The theoretical exposition is supplemented with two examples of image analysis using 2D uniform and nonuniform filter banks. A procedure to reduce the computations in image analysis is proposed. A comparison of filter synthesis between Parks–McLellan’s 2D filters and the erfc(.) demonstrates the significantly shorter calculation time of the proposed method.

Assessment of the performance and robustness of a new PID tuning technique for AVR systems

ABSTRACT In this work, a hybrid PID controller, combining Zeigler–Nichols (ZN) theory and the dominant pole placement, has been developed for the automatic voltage regulator (AVR) systems. Furthermore, the reduced order models (ROMs) of AVR systems, namely, AVR-1, AVR-2, and AVR-3, have been established using Particle Swarm Optimization (PSO), Big Bang Big Crunch (BBBC), and Pade’s approximation, respectively. Then, the proposed PID controller has been applied to both the original and developed lower order models of AVR to check the efficacy and robustness of the developed hybrid controller. It is shown that the proposed hybrid PID controller provides a very small value of the percentage peak overshoot (%M p ) and settling time (t s ). Also, the gain margin (GM) and phase margin (PM) are found to be in the desired range. Finally, the sensitivity analysis has also been performed to check the robustness of the proposed controller. The sensitivity function, complementary sensitivity function, and various performance indices have been evaluated for the proposed controller based on Bode’s Integral (BI), Tyreus–Lyuben (T–L), and Internal Model Control (IMC) approaches. The comparative studies of the results show that the proposed controller has smaller values of performance indices and sensitivity function.

A force-density framework for flexible multi-body dynamic analysis of clustered tensegrity structures

This paper develops a versatile and effective force-density framework for the flexible multi-body dynamic analysis of clustered tensegrity structures. In this framework, the force density is selected as the basic variable instead of force, and the clustered tensegrity structure is mathematically described in a vector and matrix form, encompassing topology, geometry, material, and force properties. A non-negative variable is defined as an indicator of the member stress state, and a complementary function is constructed to address the discontinuity issues that arise from the unidirectional axial stiffness of cables. Dynamic formulas are established within this force-density framework, with nodal coordinates selected as generalized parameters and formulations constructed in a matrix form. A complementary framework is established as an alternative for solving the dynamic equations, transforming the isolated steps of Newton’s iteration and cable state judgment (slack or tension) into a unified one, bringing more potential for improving solving efficiency. Numerical simulations are carried out to validate the approach, demonstrating that it effectively reveals the dynamic oscillation, tension changes, and cable slack behavior of clustered tensegrity structures during shape control. Comparative studies highlight the advantage of computational efficiency. The method proposed in this paper provides a robust mathematical model for studying clustered tensegrity structures, particularly regarding the shape control of deployable, active, and intelligent structures, aiding in understanding dynamic oscillation, tension changes, and cable slack behavior during their deformation. The methods can also be applied to cable net structures and other prestressed pin-jointed systems.

The yin and yang of pioneer transcription factors: Dual roles in repression and activation.

Pioneer transcription factors, by virtue of their ability to target nucleosomal DNA in silent chromatin, play crucial roles in eliciting cell fate decisions during development and cellular reprogramming. In addition to their well-established role in chromatin opening to activate gene expression programs, recent studies have demonstrated that pioneer factors have the complementary function of being able to silence the starting cell identity through targeted chromatin repression. Given recent discoveries regarding the repressive aspect of pioneer function, we discuss the basis by which pioneer factors can suppress alternative lineage programs in the context of cell fate control.

Modelling the time-dependent mechanical properties of thermoplastic and thermosetting polymers with Gumbel distribution functions

In this paper, we propose a simple modelling method that accurately describes the time-dependent viscoelastic behaviour of thermoplastic and thermosetting solid polymers. We performed short-term creep and stress relaxation tests on representative samples of three major classes of polymers: an amorphous, a semi-crystalline thermoplastic and a thermosetting polymer. Then, to investigate the relationship between the model parameters and the material composition, we also tested thermoplastic matrix composites with different plasticiser contents. From the short-term tests, master curves were constructed with the use of the time–temperature superposition principle. Then, the temperature dependence of the obtained shift factors was described using the Arrhenius model. The resulting creep compliance and relaxation modulus master curves were normalised and modelled with a two-parameter cumulative Gumbel distribution function (CDF) and its complementary distribution function (CCDF). For the creep and stress relaxation master curves, the median error of modelling was less than 16 % and 16.5 % in all cases, respectively. Furthermore, it was less than 2 % for the thermosetting polymer, making this model an excellent tool for describing the creep and stress relaxation behaviour of thermosetting systems. In the case of the plasticised composites, we found a strong relationship between the material composition and the location parameter of the Gumbel model. Based on this, we developed a method that can be used to estimate the evolution of the creep compliance curve for any arbitrary OLA content (between 0 wt% and 16 wt%) at any desired temperature (between 22 °C and 70 °C).

A varying-parameter complementary neural network for multi-robot tracking and formation via model predictive control

In this paper, a varying-parameter complementary neural network (VPCNN) is designed and combined with model predictive control (MPC) to solve the multi-robot tracking and formation problems via a leader–follower strategy. First, multi-robot tracking and formation problems are transformed into quadratic programming (QP) problems employing an MPC approach. Second, a nonlinear complementary function approach, i.e., the Fischer–Burmeister function, is used to map the Karush–Kuhn–Tucker conditions of the QP problem with double-ended inequality constraints to a system of nonlinear equations. Finally, the VPCNN is designed to solve the multi-robot tracking and formation problem. The effectiveness of the proposed method is demonstrated by numerical simulations, and the advantage of VPCNN in terms of solution speed is indicated by comparisons with a primal–dual neural network.

On the integral and derivative identities of bivariate Fox H-function and applications in performance analysis of wireless communications under generalized Gaussian noise

In conjunction with an algebraic, exponential, complementary error function, and a generalized Q-function, this paper provides analytical solutions for the integral of the bivariate Fox H-function (BFHF). The paper also includes derivative identities related to function arguments. The proposed formulations are then applied for analyzing the performance of point-to-point wireless communication subjected to fading, the characterization of which involves the bivariate Fox H-function, and additive white generalized Gaussian noise. Novel expressions are presented for evaluating the average symbol error probability performance considering different noise distributions, such as Gamma, Gaussian, and Laplacian. An asymptotic analysis is also conducted to determine the system’s potential diversity order. Finally, the accuracy of the analytical findings is confirmed via comparisons of numerical results with Monte-Carlo simulations.

A combination of DST precoder and ICF based-methods for PAPR suppression in OFDM signal

Abstract One well-known demerit of orthogonal frequency division multiplexing (OFDM) is its high peak-to-average power ratio (PAPR) which limits the efficiency of high-power amplifier (HPA) and also destroys its bit error rate (BER) performance. Hence, a method based on grouping of discrete sine transform (DST) precoder and iterative clipping and filtering (ICF) is proposed to reduce PAPR in this article. The DST precoder reduces PAPR to certain level by changing phase of the signal. Moreover, the ICF technique is also implemented in DST based-OFDM signal for additional minimization of PAPR. Therefore, the proposed method (DST-ICF) preserves BER performance also from other existing methods. At complementary cumulative distribution function (CCDF) = 10−3, the simulation results indicate the proposed technique that minimizes PAPR with iteration values (I = 1, I = 2, and I = 3) to 6.37 dB, 5.29 dB, and 4.81 dB respectively. Moreover, at same BER, the E b /N 0 of proposed technique with iteration value (I = 3) is achieved by 9.75 dB for quadrature phase shift keying (QPSK).

‘Very curious and romantick Views’: Captain Cook’s Antarctic explorations and aesthetic education

In all three of James Cook’s expeditions to the Pacific, visual artists were hired by the Royal Society and the Admiralty to communicate scientific information that relied on visual evidence, while conveying the embodied experience of travel. The present article focuses on the representational challenges raised by the encounter with the Antarctic during the polar explorations of the second voyage (1772–75), with an emphasis on Cook’s textual accounts and William Hodges’s sketches and illustrations, which are shown to provide an interesting angle on the contemporary debates about the respective abilities of words and images, both as paths to knowledge and as sources of aesthetic experience. After a brief discussion of the complementary epistemological function of words and images in Cook’s Pacific voyages, this article argues that the specific representational issues raised by the encounter with the Antarctic not only encouraged Cook to reflect about the value of images for the publication of his discoveries, but also partook of his own aesthetic education, with significant and long-lasting implications for the subsequent construction of polar regions in the British imagination.

Sparse Ramanujan Sequences Transform based OFDM for PAPR reduction

Sparse Ramanujan Sequences (SRS) are periodic series derived from Ramanujan Sums (RS). RS is an exponential summation used to derive infinite series expansions for arithmetic functions, whose application pervades different fields of study from classical mathematics to digital signal processing. SRS has properties similar to RS such as periodicity and orthogonality. SRS transforms allow the sparse representation of signals, hence they have many potential applications, such as denoising and compression. The application of SRS transform to reduce the Peak to Average Power Ratio (PAPR) in Orthogonal Frequency Division Multiplexing (OFDM) is proposed in this paper. The Complementary Cumulative Distribution Function (CCDF) and Bit Error Rate (BER) are used to assess the PAPR reduction performance of the proposed system. The results show that the proposed SRS transform-based OFDM system significantly reduces PAPR and BER with reduced computational complexity in comparison with the existing systems.

Understanding contextual and practical factors to inform WHO recommendations on using chest imaging to monitor COVID-19 pulmonary sequelae: a qualitative study exploring stakeholders’ perspective

BackgroundA recommendation by the World Health Organization (WHO) was issued about the use of chest imaging to monitor pulmonary sequelae following recovery from COVID-19. This qualitative study aimed to explore the perspective of key stakeholders to understand their valuation of the outcome of the proposition, preferences for the modalities of chest imaging, acceptability, feasibility, impact on equity and practical considerations influencing the implementation of using chest imaging.MethodsA qualitative descriptive design using in-depth interviews approach. Key stakeholders included adult patients who recovered from the acute illness of COVID-19, and providers caring for those patients. The Evidence to Decision (EtD) conceptual framework was used to guide data collection of contextual and practical factors related to monitoring using imaging. Data analysis was based on the framework thematic analysis approach.Results33 respondents, including providers and patients, were recruited from 15 different countries. Participants highly valued the ability to monitor progression and resolution of long-term sequelae but recommended the avoidance of overuse of imaging. Their preferences for the imaging modalities were recorded along with pros and cons. Equity concerns were reported across countries (e.g., access to resources) and within countries (e.g., disadvantaged groups lacked access to insurance). Both providers and patients accepted the use of imaging, some patients were concerned about affordability of the test. Facilitators included post- recovery units and protocols. Barriers to feasibility included low number of specialists in some countries, access to imaging tests among elderly living in nursing homes, experience of poor coordination of care, emotional exhaustion, and transportation challenges driving to a monitoring site.ConclusionWe were able to demonstrate that there is a high value and acceptability using imaging but there were factors influencing feasibility, equity and some practical considerations associated with implementation. We had a few suggestions to be considered by the expert panel in the formulation of the guideline to facilitate its implementation such as using validated risk score predictive tools for lung complications to recommend the appropriate imaging modality and complementary pulmonary function test.

Bank fundamental dynamics: the role of optimal bank management

Purpose This study aims to investigate the dynamic relationships between profitability, credit risk, liquidity risk and capital in Indonesian banking industry. Design/methodology/approach The authors use a panel vector autoregression model that incorporates macroeconomic variables: growth, interest rate, foreign exchange. The analysis is based on a monthly panel data set of 88 banks spanning from January 2012 to September 2021, which comprises 10,296 bank-month observations. Findings Our key findings highlight (i) permanent credit cost and liquidity cost pass through practices, (ii) complementary function of liquidity and capital, (iii) earning management motivated asset write off and (iv) credit risk-liquidity risk neutrality. In addition, the authors observe that the banks demonstrated resilience to macroeconomic shocks. Research limitations/implications Our study have shown some interesting dynamic patterns of fundamentals; nevertheless, unified theoretical underpinning of the process is still unavailable. This should be an important future reasearch avenue. Practical implications The study brings significant implications for regulatory and supervisory practices aimed at enhancing the financial stability of banks. Originality/value We conduct estimation of Indonesian banks system in dynamic perspective and perform impulses responses.

Dependence of rain attenuation on rain rate and drop size distribution for Ka-band satellite communication over India

The Raindrop size distribution (DSD) is the most effective parameter to calculate rain-induced attenuation, which can be severe at Ka-band and higher frequencies. The authors have investigated the impact of rain rate and DSD on rain-induced specific attenuation over a tropical location Kolkata, India. DSD data from disdrometer has been used to calculate the specific rain attenuation with the help of Mie scattering theorem. Low to medium drop diameters (up to 3 mm) are the largest contributors to the various classes of rain rate and attenuation. Double peaks of drop sizes are significant for medium rain rate. The contribution of smaller drop diameters decrease, whereas the contribution of higher drop diameters increase with increasing rain attenuation. At lower rain attenuation, (up to 1.5 dB), complementary cumulative distribution function (CCDF) shows higher value for stratiform rain, with respect to convective rain. The higher attenuation occurrences are mostly observed during 12–18 Indian standard time (IST), i.e., in the afternoon. The results will be helpful for Ka-band (GSAT-14) and higher frequency satellite communication channel modeling over India.

Bingham plastic fluids flow analysis in multimembranes fitted porous medium

A mathematical analysis is presented for the flow of a Bingham plastic fluid propelled by the multi-membranes pumping mechanism through porous media. Two successive membranes with different amplitude, diameter, and phase lag, are fitted at the upper wall of the channel, and the lower wall is stationary. Due to the simultaneous propagation of both membranes, the pressure is generated at the membrane's position, which helps in propelling the fluids in forward and backward directions depending upon the compression and expansion cycles of the membranes. The low Reynolds number assumption and lubrication theory are utilized to linearize the governing equations, which are further analytically derived, and then employing MATLAB codes to compute the illustrations for the interpretation of the results. The effects of key parameters like plug flow region, pore size and diameter of membranes on the velocity field, wall shear stress, pressure gradient, fanning friction factor, head loss and particle trajectories, are analysed in the microchannel. Results of the present model conclude that the geometrical properties of membranes, rheological properties of fluids and porosity of the medium significantly alter the flow and pumping characteristics which give valuable insights for the design of micro-valve less pumping actuators to be aimed at controlling microscale transport processes in various medical diagnoses and treatments.

Comparative evaluation of four actual evapotranspiration models over different ecosystems and climate zones in China

ABSTRACT To better understand the discrepancies in evapotranspiration (ET) simulations between ET models, we intercompared four models in China: Priestley–Taylor Jet Propulsion Laboratory (PT-JPL), Penman–Montieth–Leuning Version 2 (PML-V2), Sigmoid Generalized Complementary Function (SGCF), Mapping Evapotranspiration at High Resolution with Internalized Calibration (METRIC). Data from 18 flux sites were used to evaluate the model performance at daytime (when incident shortwave radiation is greater than 20 W/m2) scales. To compare more fairly, we took the intersection of the outputs from four models for the analyses in the main text. All models yielded acceptable results, with PML-V2 or SGCF performing best at most sites. The average coefficient of determination and root mean square error among all sites of LE (latent heat of ET) were 0.72 and 51.71 W/m2 for PT-JPL, 0.80 and 46.65 W/m2 for PML-V2, 0.79 and 41.13 W/m2 for SGCF, 0.70 and 51.09 W/m2 for METRIC. PT-JPL and PML-V2 underestimated ET at most sites, whereas SGCF overestimated, potentially due to uncertainties in the vegetation indices and ET constraint parameters. Compared to measurements, PT-JPL underestimated the proportion of transpiration to evapotranspiration (0.81 versus 0.59), while PML-V2 overestimated (0.81 versus 0.90). Furthermore, all models performed best in the semi-arid zone dominated by grassland sites.

Exploring and Analyzing a Hybrid PAPR Reduction Method for OFDM Optimization

Orthogonal Frequency Division Multiplexing (OFDM) is a effective modulation technique widely used in modern communication systems, including 5G and wireless networks because of its high spectral efficiency and robustness towards multipath fading. However, OFDM signals are characterized by a high Peak-to-Average Power Ratio (PAPR), which can severely impact the power efficiency and operational cost of these systems. This research investigates and analyse effectiveness of two conventional PAPR reduction methods that is Selective Mapping (SLM), and Partial Transmit Sequence (PTS) with incorporating their approach of PAPR reduction to develop a hybrid variant: SLM-PTS. This study utilized MATLAB simulations to implement and test each PAPR reduction technique on a standard OFDM system model. Parameters such as the number of subcarriers, oversampling factor, and modulation types were systematically varied to analyze the impact on PAPR, BER, and computational complexity. The effectiveness of each technique was measured using the Complementary Cumulative Distribution Function (CCDF) of PAPR values and BER performance under different channel conditions. Key findings reveal that hybrid techniques, particularly SLM & PTS, offer significant improvements in PAPR reduction compared to traditional methods alone, without a corresponding increase in BER or computational overhead. The research underscores the potential of hybrid PAPR reduction techniques to significantly enhance the efficiency and reliability of OFDM systems. These findings have important implications for the design and optimization of next-generation wireless communication systems, suggesting that hybrid approaches can provide a balanced solution to the longstanding issue of PAPR in OFDM transmissions. This study contributes valuable insights into the practical application of combined PAPR reduction strategies, offering a pathway toward more power-efficient and robust OFDM technologies. Keywords : OFDM, PAPR, CCDF, SLM and PTS

Pilot Projects to Secure Local Supply in Rural Areas. Start-ups, Community-oriented Entrepreneurs and Public Funding as Drivers?

The usual store formats can hardly be operated economically in places with fewer than 2,500 inhabitants. In line with the spiral theory, the resulting retreat from the area offers new commercial opportunities for innovative forms of offering, such as staff-free 24/7 markets or online ordering options. At present, a wide variety of actors are experimenting with new and flexible approaches, and it does not yet seem foreseeable which models will ultimately prevail. How can the initial experiences be systematized and what is the potential for establishment? To this end, we compare five pilot projects that use decentralized, mobile and digital formats to bring everyday goods to consumers. For the five case studies, 35 semi-structured interviews were conducted with experts and customers. Central comparative dimensions are the context of emergence and the actor constellations, the contribution to local supply, the economic viability as well as the social function of the offers. The results show that two cases are strongly subsidy-driven or depend on public support. In two other cases, the social function dominates with the involvement of socially oriented enterprises, where the approaches can rather fulfill a complementary supply function. Finally, there is also a new format that at least has the potential to be rolled out on a large scale in rural areas of Germany and beyond.

DERIVATION OF EXPRESSION FOR PHOTOCURRENT DENSITY FOR NON-DESTRUCTIVE TESTING OF 3D PRINTING FILAMENT BY MEANS OF TERAHERTZ SPECTROSCOPY

This report presents a revised expression for the photocurrent density in terahertz spectroscopy, which is a non-destructive testing technique of particular interest to the authors in the context of 3D printed parts. 3D printing, also known as additive manufacturing, involves creating three-dimensional objects based on computer-aided design (CAD) models. The process entails depositing, joining, or solidifying material under computer control, layer by layer.
 
 Defects in 3D printing, such as weak infill, gaps in thin walls, inconsistent extrusion, layer separation, and bed drop, can lead to low printing quality and render some printed parts unfit and unsafe for use. Moreover, the ability to tamper with internal layers without altering the exterior could result in the production of maliciously defective parts without detection. Therefore, it is crucial to test 3D printed details and filaments at each stage of processing using non-destructive methods.
 
 A comprehensive review of the relevant literature indicates the potential for enhancing measurement accuracy through various improvements in terahertz spectrometer models. The mathematical model for the photocurrent involves a convolution integral of the current density and the laser radiation pulse that irradiates the surface of the material under study. The expression within the integral incorporates parameters such as the duration of the optical pulse, carrier lifetime, and momentum relaxation time. By evaluating the integral, the result can be obtained as two terms, each being a product of an exponent and a complementary error function with the same parameters mentioned earlier.
 
 The calculation involves several steps, including a change of variables during integration. Verification using Maple software demonstrates agreement with analytical calculations and suggests a pathway for further refinement of the expression for the photocurrent density. The Maple program influenced the results by means of repeating same calculation with aid of computer and allowing to compare if analytical results are same and true, also it could be use for simulation and example calculation, for results graphical representation. 
 
 The connection between the obtained mathematical expression and its relation to 3D printing (additive manufacturing) exists. The explanation is in that the 3D printer uses filament, filament has defects, defectoscopy of filament in the terahertz domain have models and methods. The research of defectoscopy models and methods is helpful to increase accuracy of measurement of filament defect parameters and account on it and improve the quality of 3D printed details.

Larger particle size distribution of environmental RNA compared to environmental DNA: a case study targeting the mitochondrial cytochrome b gene in zebrafish (Danio rerio) using experimental aquariums.

Environmental RNA (eRNA) analysis is conventionally expected to infer physiological information about organisms within their ecosystems, whereas environmental DNA (eDNA) analysis only infers their presence and abundance. Despite the promise of eRNA application, basic research on eRNA characteristics and dynamics is limited. The present study conducted aquarium experiments using zebrafish (Danio rerio) to estimate the particle size distribution (PSD) of eRNA in order to better understand the persistence state of eRNA particles. Rearing water samples were sequentially filtered using different pore-size filters, and the resulting size-fractioned mitochondrial cytochrome b (CytB) eDNA and eRNA data were modeled with the Weibull complementary cumulative distribution function (CCDF) to estimate the parameters characterizing the PSDs. It was revealed that the scale parameter (α) was significantly higher (i.e., the mean particle size was larger) for eRNA than eDNA, while the shape parameter (β) was not significantly different between them. This result supports the hypothesis that most eRNA particles are likely in a protected, intra-cellular state, which mitigates eRNA degradation in water. Moreover, these findings also imply the heterogeneous dispersion of eRNA relative to eDNA and suggest an efficient method of eRNA collection using a larger pore-size filter. Further studies on the characteristics and dynamics of eRNA particles should be pursued in the future.

Multivariate canonical correlation analysis identifies additional genetic variants for chronic kidney disease

Chronic kidney diseases (CKD) have genetic associations with kidney function. Univariate genome-wide association studies (GWAS) have identified single nucleotide polymorphisms (SNPs) associated with estimated glomerular filtration rate (eGFR) and blood urea nitrogen (BUN), two complementary kidney function markers. However, it is unknown whether additional SNPs for kidney function can be identified by multivariate statistical analysis. To address this, we applied canonical correlation analysis (CCA), a multivariate method, to two individual-level CKD genotype datasets, and metaCCA to two published GWAS summary statistics datasets. We identified SNPs previously associated with kidney function by published univariate GWASs with high replication rates, validating the metaCCA method. We then extended discovery and identified previously unreported lead SNPs for both kidney function markers, jointly. These showed expression quantitative trait loci (eQTL) colocalisation with genes having significant differential expression between CKD and healthy individuals. Several of these identified lead missense SNPs were predicted to have a functional impact, including in SLC14A2. We also identified previously unreported lead SNPs that showed significant correlation with both kidney function markers, jointly, in the European ancestry CKDGen, National Unified Renal Translational Research Enterprise (NURTuRE)-CKD and Salford Kidney Study (SKS) datasets. Of these, rs3094060 colocalised with FLOT1 gene expression and was significantly more common in CKD cases in both NURTURE-CKD and SKS, than in the general population. Overall, by using multivariate analysis by CCA, we identified additional SNPs and genes for both kidney function and CKD, that can be prioritised for further CKD analyses.