Complex Schemes Research Articles

A 10-20 GHz 6-Bit High-Accuracy Digital Step Attenuator with Low Insertion Loss in 0.15 µm GaAs p-HEMT Technology.

In a beamforming circuit for a modern broadband phased-array system, high accuracy and compactness have received sufficient attention as they are directly related to side lobe level and fabrication cost, respectively. In order to meet the low phase error required, this paper proposed an ultra-broadband 6-bit digital step switched-type attenuator (STA) with capacitive/inductive compensation networks. Compared to the conventional methods, the proposed technique employs an improved simplified T-structure with capacitive compensation networks, which simultaneously achieves low insertion loss and high-accuracy amplitude/phase control. In addition, on-chip level shifting circuit is integrated to avoid complex control schemes. The strategy of prioritizing return loss is adopted to alleviate the performance degradation caused by impedance mismatch after cascade. As a proof-of-principle demonstration, a wideband 6-bit STA with core area of only 0.5 mm × 1.8 mm was designed via 0.15-micrometer GaAs pHEMT technology. It exhibits ultra-broadband operation with a 31.5 dB amplitude tuning range and a 0.5 dB tuning step. The insertion loss of the reference state is 4-5.3 dB. The return loss is better than 15 dB for all the 64 states. The RMS amplitude and phase errors are less than 0.2 dB and 2° over the 10 to 20 GHz.

Recent Advances in Chitosan-based Nanocomposite Membrane Materials for Water Treatment

In recent years, research on chitosan (CS)-based nanocomposite membranes has made significant progress in the field of water treatment. This innovative membrane material incorporates a variety of excellent biological properties, including the biocompatibility and adsorption properties of the natural polymer chitosan (CS) and the introduction of nanotechnology. Furthermore, it enables the composite material to have excellent functional characteristics, such as higher water flux and selectivity. Furthermore, the enhancement of the structural and intrinsic properties of membrane materials will facilitate the attainment of further advancements in a multitude of performance characteristics, including stability, durability, and adsorption selectivity. Consequently, this field has become a promising area of research in water treatment technology, attracting extensive research and attention. However, the publication of a large number of related research reports in recent years, accompanied by numerous and complex performance optimization schemes and research ideas, has resulted in a paucity of articles that summarize these performance optimization strategies and research paths. Consequently, there are few meaningful references for subsequent research. In light of the aforementioned considerations, this paper will provide a comprehensive review of the most recent research advances in the field of water treatment, with a particular focus on the latest research strategies and frameworks for optimizing the performance of related materials. Furthermore, this paper will illustrate the innovative and beneficial applications of such materials from various vantage points, including their sources and preparation processes. It is anticipated that this paper will serve as a valuable source of inspiration for further research in this field.

Application of fiberglass pipes in geothermal circulation systems

The results of calculating the coefficient of thermal conductivity of the developed construction of the pipeline from multilayer composite spatially oriented fiberglass are given. A method of calculating the coefficient of thermal conductivity of a pipe wall with a complex structure of reinforcement has been developed. The fiberglass pipe is made by the continuous method of oblique-layer longitudinal-transverse winding on a self-feeding frame of reinforcing pseudo-tape moistened with a binder in the form of a rarefied mesh. With each rotation of the mandrel, it shifts by the amount of hardening of the obtained two-component material under the influence of temperature. A comparison of calculated and experimental data was made. When comparing various known calculated dependencies and experimental values, the accepted physical model and the real structure of the material are determined. The known dependences obtained for a medium with infinite long parallel cylindrical inclusions for unidirectional and orthogonally reinforced materials and therefore for materials with a complex structure and scheme of reinforcements give errors and deviations. The work assumes that fiberglass consists of two components - a reinforcing filler and a binder with pores, the reinforcing fibers are endless and have a circular cross-section, the reinforcing fibers are evenly distributed in the matrix of the binder, there is an ideal thermal contact at the boundaries of the distribution between the reinforcement and the binder. Experimental data on determining the transverse thermal conductivity of unidirectional fiberglass rods with reinforcement based on aluminoborosilicate or magnesium-aluminosilicate glass and epoxy binders showed the smallest error in comparison with the calculated ones (8-10%). They investigated the fact that the coefficient of thermal conductivity of a fiberglass pipe is 100 times lower than that of a steel pipe. It was determined that it is possible to replace a steel pipe with a diameter of 219 mm with a fiberglass pipe with a diameter of 146 mm.

Ways to increase the effectiveness of hypertension correction during antitumor therapy with the use of VEGF inhibitors

In recent years, cardioncology has rapidly become responsible for comprehensive decision-making appropriate cancer patients receiving cardiotoxic cancer therapy. Currently, the implementation of a multidisciplinary approach in the correction of adverse events using various drug antitumor therapy regimens is becoming increasingly relevant. In particular, given the widespread use of vascular-endothelial growth factor inhibitors, both at the heart of complex schemes and in mono-supportive modes. It is important to timely identify and correct such a clinically significant adverse event as an increase in blood pressure at the time of administration and in the early follow-up period. Adherence to standard drug regimens for hypertension, which usually provide satisfactory blood pressure control between cycles of administration of vascular-endothelial growth factor inhibitors, in a number of patients did not allow the same effective retention of blood pressure in the planned intervals with the administration of bevacizumab. The intensification of drug therapy for hypertension, both at the pre-infusion stage and at the time of an increase in blood pressure, was of a multidirectional nature. Search and summarize information on the availability and development of physiotherapeutic treatment methods for the correction of hypertension during antitumor therapy in cancer patients using vascular-endothelial growth factor inhibitors. 35 literature sources were analyzed. There are no data on the development of physiotherapeutic methods for the treatment of bevacizumab-induced hypertension. Domestic sources ― 25 articles. Foreign sources ― 10 articles. An analysis of the literature concluded that there is a lack of research on the development of physiotherapeutic methods for the treatment of bevacizumab-induced hypertension. In order to reduce the cardiotoxicity of humanized recombined monoclonal antibodies, maintain the dose interval period, improve survival and eliminate the need for dose adjustment of antihypertensive drugs, it is proposed to consider the use of preformed physical factors in the treatment of bevacizumab-induced hypertension.

Оценка состояния вентиляционной сети рудного тела Le-3 на месторождении «Джульетта»

Effective, high-quality and steady ventilation of mine workings is one of the main factors that determine safe working conditions in an underground mine. The Juliet deposit is characterized with an irregular shape and varying dips and strikes. In some cases, it consists of isolated and mutually remote deposits with different mining and geological characteristics. These features of the deposit dictate the use of complex schemes for the development and mining of the deep-lying layers, which results in formation of a very extensive and branched network of underground workings. The specific features in the development of the Juliet deposit include the fact that a large number of mining blocks are in operation at the same time, and extraction of these block can be carried out using different mining systems. Intensive removal of dust and gases can be ensured only when a sufficiently large amount of air is supplied to the mine and the individual working faces. In order to overcome the overall air drag in the mine, it is necessary to use high-performance and high-pressure fans that would consume enormous power.

ENERGY EFFICIENCY INCREASING OF ORE ENRICHMENT WASTES’ PROCESSING BY ELECTRICAL DISCHARGE METHOD

A promising and accessible raw material, comparable in terms of gold and silver content to natural ore deposits, is the lying tailings of ore flotation. Currently, billions of tons of ore tailings have been accumulated, the content of valuable components in which sometimes exceeds those in natural deposits. The processing of ore tailings from tailings for the extraction of non-ferrous metals in most cases requires complex beneficiation schemes, and in terms of technical and economic indicators and the quality of concentrates, they are uncompetitive compared to products of natural raw materials. An electric discharge method of disintegration of ore beneficiation waste to increase the number of available target components, based on the rational organization of crushing and grinding processes in relation to beneficiation tasks, was experimentally investigated. The pressure values of the compression waves generated by the electric discharge were determined to calculate the radius of effective selective influence on the studied waste samples of flotation beneficiation of copper-zinc ores. The necessary conditions for the effective operation of the technological part of the equipment are established: in the volume of the disintegrator, the pressure, created by the electric discharge, should not be less than the tensile strength of the processed material and at the same time should not exceed the strength of the disintegrator’s material. The use of the electric discharge method ensures the selectivity of disintegration of the material along the interphase boundary "dead rock - mineral inclusion", this circumstance allows to achieve a significant increase in the amount of mined valuable metals and simultaneously reduction of energy consumption by 2 - 4 times. Increasing energy efficiency is considered by the way of example with copper-zinc ore concentration’s waste. The increase in the number of target metals available in wastes of flotation concentration of copper-zinc ore after their electric discharge treatment is shown. The increase in the amount of copper extracted from copper-zinc ore enrichment waste was from 40 to 93% by mass, extracted zinc - from 39 to 94% by mass, silver extracted - from 16 to 50% by mass.

Specificity of Using Phonograms in Popular Music

The purpose of the research. This article attempts to characterise the interaction of sound directing practices with popular music during stage performances and concerts. The research methodology employed to address the set objectives consisted of a historical-cultural approach to analyse the development process of digital sound recording formats and innovations in concert touring practices, a philosophical-aesthetic approach when considering the aesthetic principles of the music and sound concept in concert performances, and a method of theoretical generalisation to draw conclusions and justify the specific features of the outlined issues. The scientific novelty of this article lies in being the first in Ukrainian science to substantiate and sequentially describe the work on recording playback phonograms in the studio, as well as their subsequent use together with live performances by artists during a long-anticipated concert tour as a unified music and sound image of the creative ensemble, based on teaching and sound engineering experience. Conclusions. With the development of digital means of artistic expression, the use of phonograms in popular music has gained significant momentum, with the main argument in favour being the "the main focus is the show programme". This, to some extent, justifies artists' performances to pre-recorded playback. Therefore, based on analyzed examples, the specificity of the sound engineer's work with a complex scheme of simultaneous use of phonograms from a player-recorder (HDR) and the sound accompaniment of the creative ensemble during stage performances is elucidated. The issues related to this practice and recommended methods to avoid them are highlighted. It is determined that the concert sound director is a central figure in creating a popular music stage performance. The level of artistic and spectacular event, regardless of the chosen performance format (playback or live performance) of the creative performer/ensemble, depends on their professional skills and practical experience in utilising innovative sound equipment. The use of a full or partial phonogram during a concert, presented to an enthusiastic audience, is a matter of professional ethics and the integrity of the artist(s). Failure to uphold these high components results in complete ruin of the performer's or creative ensemble's stage career. The final choice remains with the artists. Keywords: sound directing, popular singing, backing vocals, instrumental performance, studio sound recording, phonogram, sound equipment.

Identifying farmers' response to changes in marginal and average subsidies using deep learning

AbstractMuch of the developed world has adopted substantial, complex agricultural subsidy schemes in an attempt to produce desired rural livelihood and environmental outcomes. Understanding how farmers adjust their production activity in response to farm subsidies is crucial for setting optimal agricultural policy. Whereas standard economic theory suggests that farmers largely adjust production levels in response to prices and marginal subsidy rates, recent work in consumer behavior suggests that average (dis‐)incentives may play a relevant role. We use a unique panel covering all farms applying for subsidies in Norway and a flexible deep‐learning method to exploit kinks in the subsidy scheme to answer whether farmers respond more to average or marginal subsidies. In contrast to the standard economic theory of production, we find suggestive empirical evidence that farmers respond more to changes in average payments than to changes in marginal payments. We anticipate that our findings on the relevance of average payment levels for farmers' decision making may inspire further theoretical and empirical inquiries into agricultural policy effects. The study also highlights how novel deep‐learning tools can be applied for detailed policy analysis and what advantages and challenges come with it. We believe that this approach has substantial potential for analysts and policymakers to evaluate and predict the impacts of policy options.

The Invisible Lake of Sa’ādat-ābād and the Safavid Architecture of Affect

Abstract Isfahan’s selection as the capital of Persia’s Safavid Empire (1501–1736) at the turn of the seventeenth century set off multiple phases of growth in the city. This included the development of Shah Abbas II’s (r. 1642–66) palatial complex of Sa’ādat-ābād, which encouraged Isfahan’s engagement with the nearby river Zāyandehrud. This article expands the discourse examining the river beyond the domain of nature by exploring the Zāyandehrud as a designed environment and a site of architectural imagination and action. As shown in this study, the river and the complex interconnections between natural and cultural systems played a central role in shaping the scheme of this royal complex. While a lack of visual and archaeological evidence has kept rivers and lakes on the sidelines in most studies of premodern Islamic water architecture, this article provides a new perspective on the roles of such bodies of water through a close reading of Safavid poetry, contemporary prose, spatial analysis, and architectural reconstructions.

Fraud from a CPA named Laws: missed red flags and conflict of interest

Research methodology The case uses primary source documents, such as the court cases brought forth by the SEC and US District Attorney, for the specifics about the fraud and secondary sources for further background information about the town and industry. The individuals in the case are not disguised. The authors have no connection to the case. Case overview/synopsis Thomas Laws was a CPA, a registered investment advisor and a real estate broker. Laws made a poor business investment. Instead of taking the financial hit, Laws orchestrated a complex Ponzi scheme using clients from his CPA practice and embezzling money from an employer, Santa Fe Gold Corporation. Laws’ scheme continued until his employer confronted him about missing funds. Frank Mueller, the CFO of Santa Fe, did not exercise the due diligence necessary until it was too late. Rest’s framework for ethical decision making is used to frame the ethical decisions Mueller can make. The case examines the conflict-of-interest guidance issued by the American Institute of Certified Public Accountants (AICPA) and allows students to examine the due diligence and controls needed by employers and prospective investors. Complexity academic level This case is designed for undergraduate accounting students taking Intermediate Accounting I, ACCT 0312 at the authors’ institution, typically junior-level students. It would be appropriate whenever you introduce the AICPA Code of Professional Conduct during an ethics discussion.

The Generalization of Bidirectional Dual Active Bridge DC/DC Converter Modulation Schemes: State-of-the-Art Analysis under Triple Phase Shift Control

The main objective of this paper is to provide a thorough analysis of currently used modulation control schemes for single-phase bidirectional dual active bridge DC/DC converters. In this article, it will be shown that single phase shift, extended phase shift and dual phase shift modulation schemes are special cases of the triple phase shift (TPS) modulation scheme. The article aims to highlight six TPS switching modes and their complements with operational constraints. Unlike previous studies that regarded TPS as a complex scheme, this paper simplifies the analysis of each mode and aims to standardize the understanding of TPS modulation for dual active bridge (DAB) converters. Power equations, range of power transferred and zero-voltage switching (ZVS) are derived for all the modes under TPS without assuming fundamental component analysis. Additionally, a generic optimization algorithm is developed to show the advantages of TPS modulation, and thus, the analysis in this paper offers a valuable insight for single-phase DAB converter designers in identifying a wide range of optimization algorithms to achieve higher efficiency under TPS modulation. This analysis contributes to the advancement of bidirectional DAB converter technology and facilitates its application in various power electronic systems.

A sign that used to annoy me, and still does

We provide a proof of the following fact: if a complex scheme Y has Behrend function constantly equal to a sign σ∈{±1}, then all of its components Z⊂Y are generically reduced and satisfy (−1)dimC⁡TpY=σ=(−1)dim⁡Z for p∈Z a general point. Given the recent counterexamples to the parity conjecture for the Hilbert scheme of points Hilbn(A3), our argument suggests a possible path to disprove the constancy of the Behrend function of Hilbn(A3).

Assessment of the effectiveness of measures to improve the patient routing system in the provision of planned medical care (experience of Tomsk region)

Introduction. This article reviews the results of the development and implementation of organizational solutions aimed at reducing the time of providing routine medical care to patients in outpatient settings and increasing its availability. Among the reasons negatively affecting the waiting times for medical care are complex routing schemes and the high level of administrative overhead that accompanies each stage of the treatment and diagnostic process.Aim: To develop and evaluate the effectiveness of measures to improve the system of organization of planned medical care on the example of medical organizations of Tomsk region.Material and Methods. The study included medical organizations providing primary health care in outpatient settings (31 institutions). The study was conducted in stages: 2018–2019 the main set of measures (creation of offices of the organization of planned care) was developed and implemented, 2020–2021 – summarized interim results, 2022 – performance assessment was carried out. For comparative analysis all medical organizations were divided into 2 groups (group A and group B) depending on implementation of planned activities. Statistical processing was performed using the Statistica 10.0.228.8 software package.Results. It was found that the waiting time for a doctor’s consultation Group A reduced by 5.5% (p = 0.025) in 2019 compared with 2018, in contrast to Group B. The waiting time for a routine diagnostic examination in Group A also reduced by 16.6% in 2019 compared to 2018 (p = 0.041), while no differences were found between waiting times for routine diagnosis in Group B for the same period (p = 0.101).Summary. The study has shown that the problems of accessibility of planned medical care can be effectively solved through the creation of a patient flow management system at all stages of the treatment and diagnostic process.

Fast functional mapping of ligand-gated ion channels

Ligand-gated ion channels are formed by three to five subunits that control the opening of the pore in a cooperative fashion. We developed a microfluidic chip-based technique for studying ion currents and fluorescence signals in either excised membrane patches or whole cells to measure activation and deactivation kinetics of the channels as well as ligand binding and unbinding when using confocal patch-clamp fluorometry. We show how this approach produces in a few seconds either unidirectional concentration-activation relationships at or near equilibrium and, moreover, respective time courses of activation and deactivation for a large number of freely designed steps of the ligand concentration. The short measuring period strongly minimizes the contribution of disturbing superimposing effects such as run-down phenomena and desensitization effects. To validate gating mechanisms, complex kinetic schemes are quantified without the requirement to have data at equilibrium. The new method has potential for functionally analyzing any ligand-gated ion channel and, beyond, also for other receptors.

Regular-singular connections on relative complex schemes

Deligne's celebrated "Riemann--Hilbert correspondence" relates representations of the fundamental group of a smooth complex algebraic variety and regular-singular integrable connections. In this work, we show how to arrive at a similar statement in the case of a smooth scheme $X$ over the spectrum of a ring $R=\mathbb C[[t_1,\ldots, t_r]]/I$. On one side of the correspondence we have representations on $R$-modules of the fundamental group of the special fibre, and on the other we have certain integrable $R$-connections admitting logarithmic models. The correspondence is then applied to give explicit examples of differential Galois groups of $\mathbb C[[t]]$--connections.

Affine transformations accelerate the training of physics-informed neural networks of a one-dimensional consolidation problem

Physics-informed neural networks (PINNs) leverage data and knowledge about a problem. They provide a nonnumerical pathway to solving partial differential equations by expressing the field solution as an artificial neural network. This approach has been applied successfully to various types of differential equations. A major area of research on PINNs is the application to coupled partial differential equations in particular, and a general breakthrough is still lacking. In coupled equations, the optimization operates in a critical conflict between boundary conditions and the underlying equations, which often requires either many iterations or complex schemes to avoid trivial solutions and to achieve convergence. We provide empirical evidence for the mitigation of bad initial conditioning in PINNs for solving one-dimensional consolidation problems of porous media through the introduction of affine transformations after the classical output layer of artificial neural network architectures, effectively accelerating the training process. These affine physics-informed neural networks (AfPINNs) then produce nontrivial and accurate field solutions even in parameter spaces with diverging orders of magnitude. On average, AfPINNs show the ability to improve the {mathscr {L}}_2 relative error by 64.84% after 25,000 epochs for a one-dimensional consolidation problem based on Biot’s theory, and an average improvement by 58.80% with a transfer approach to the theory of porous media.

Spectral method of electrical circuits accelerated simulation with thyristors

Purpose. The development of transient processes calculation method in electric circuits with thyristors based on the use of functions approximation by orthogonal polynomials.
 Methodology. Functions approximation by orthogonal polynomials, numerical methods of differential equations integration, matrix methods, programming, theory of electric circuits.
 Obtained results. The method of solution function polynomial approximation of integro-differential equations of state, which describes the transient processes of an electric circuit with thyristors, is used in this paper. The used method showed the advantages over other known methods in increasing the accuracy and reducing the simulation time of transient electrical processes by more than 6 times.
 Findings. The solution is approximated by a series of Chebyshev polynomials. The integro-differential equations of state are transformed into linear algebraic equations for special depiction of the solution functions. The depiction of functions of true currents in the equivalent circuit is interpreted as direct currents. Such a schematic model creates visibility for a researcher performing simulation of transient electrical processes.
 Practical value. The proposed methods discover the possibility of using the apparatus of direct current electric circuits’ theory for transient processes in complex schemes modeling with thyristors.

Harnessing optical vortices to control current flow via quantized torque in coherently prepared multilevel atoms

This study delves into the interaction between coherently prepared trapped atoms and optical vortices, focusing on the intriguing phenomenon of light-induced torque enhancement and the resultant persistent current flow. Beginning with a three-level atom ensemble in the Λ configuration, we initiate a coherent superposition of lower levels to establish a coherent population trapping medium. The atoms interact with a pair of optical vortices, producing a quantized torque on each trapped atom that is directly proportional to the topological charge of the inhomogeneous coupling beams. This torque imparts a rotation to the entire ensemble, thereby generating a striking ring-shaped atomic current flow. With careful manipulation of the initial internal state of the atoms and the strength of the vortex pair, we can control the magnitude of the torque. Extending the model to include more complex level schemes with additional laser beams offers even greater potential for enhancing light-induced torque and refining our control over the current flow.

Automated software and hardware complex based on an eddy current sensor for studying the properties of thin films

The variety of existing thin-film structures used in modern science and technology is described. The design of a miniature eddy current transducer was developed and improved. Methods for determining the properties of films were presented. The main design parameters of the developed transducer are described and a scheme of operation complex is presented. The results of scanning electrically homogeneous and inhomogeneous films are presented. It was possible to establish the degree of uniformity of the conductivity of the film by constructing histograms that display the number of points with different electrical conductivity.

Modeling Impacts of Urbanization on Winter Boundary Layer Meteorology and Aerosol Pollution in the Central Liaoning City Cluster, China.

The influence of urbanization on the frequent winter aerosol pollution events in Northeast China is not fully understood. The Weather Research and Forecasting Model with Chemistry (WRF-Chem) coupled with urban canopy (UC) models was used to simulate the impact of urbanization on an aerosol pollution process in the Central Liaoning city cluster (CLCC), China. To investigate the main mechanisms of urban expansion and UC on the winter atmospheric environment and the atmospheric diffusion capacity (ADC) in the CLCC, three simulation cases were designed using land-use datasets from different periods and different UC schemes. A comparative analysis of the simulation results showed that the land-use change (LU) and both LU and UC (LUUC) effects lead to higher surface temperature and lower relative humidity and wind speed in the CLCC by decreasing surface albedo, increasing sensible heat flux, and increasing surface roughness, with a spatial distribution similar to the distribution of LU. The thermal effect leads to an increase in atmospheric instability, an increase in boundary layer height and diffusion coefficient, and an increase in the ADC. The LU and LUUC effects lead to a significant decrease in near-surface PM2.5 concentrations in the CLCC due to changes in meteorological conditions and ADC within the boundary layer. The reduction in surface PM2.5 concentrations due to the LU effect is stronger at night than during daytime, while the LUUC effect leads to a greater reduction in surface PM2.5 concentrations during the day, mainly due to stronger diffusion and dilution caused by the effect of urban turbulence within different levels caused by the more complex UC scheme. In this study, the LU and LUUC effects result in greater thermal than dynamic effects, and both have a negative impact on surface PM2.5 concentrations, but redistribute pollutants from the lower urban troposphere to higher altitudes.