Resistor Network Research Articles

‘Round ring on the floor’—Collective resistance networks in female factories

‘Round ring on the floor’—Collective resistance networks in female factories

A novel combined model for energy consumption performance prediction in the secondary air system of gas turbine engines based on flow resistance network

Predicting the comprehensive energy consumption is challenging for the complicated secondary air system. To solve this problem, a universal flow resistance element has been constructed to describe different components more accurately. And a novel flow resistance network is proposed to calculate the system's energy consumption. This network can be analyzed by the flow resistance characteristics of its components to estimate the energy consumption of each component and the energy loss of the system. Furthermore, a flow resistance parameter is defined as a unique factor to determine the magnitude of flow resistance for each component. Compared to experimental and numerical results, both models demonstrate sufficient accuracy in calculating mass flow rates and entropy increments, with the maximum deviation less than 1.2%. The above two models are also applied to predict flow losses of elements with changes in pressure and inlet total temperature, with the maximum deviation less than 4.5%. Based on the flow resistance network, the aerodynamic performance of each element can be easily computed by the inlet and outlet boundary of this system, regardless of whether the elements are arranged in series or parallel.

Low cost energy-efficient preheating of battery module integrated with air cooling based on a heat spreader plate

Integration of heating and cooling functions has aroused increasing interest for the automotive battery modules. The proposed cylindrical 18650 battery module is equipped with an external sleeved spreader plate (SHSP), which features low thermal resistance and a large exchange area as an efficient heat transfer medium. The transient temperature characteristics of the battery module were experimentally investigated in both cooling mode and heating mode, respectively. In cooling mode, the temperature characteristics of the battery module equipped with SHSP were examined. With an inlet velocity of 1 m/s and a discharge rate of 3 C, the temperature rise and temperature difference are only 12.9 °C and 2.83 °C at an ambient temperature of 25 °C, respectively. In heating mode, the heat-up characteristics of the battery module were experimentally examined at a subzero temperature of −20 °C under three different heating protocols: continuous heating, fast-rest-slow heating, and slow-rest-fast heating. Immune from potential effects on the battery internal degradation, the heating rate of the battery module in a continuous heating protocol could reach 6.98 °C/min with a heating efficiency of 69.8%, which outperforms the existing external heating modes.Additionally, the fast-rest-slow heating protocol has clear-cut advantages in terms of heating rate while maintaining a smaller temperature difference during the heating phase. Finally, a simplified thermal resistance network model for the cell is established based on the analysis of the one-dimensional steady state heat transfer. According to projections, the thermal resistance of the present heating model is 2.03 K/W, which is less than the hot air convection heating model by 5.24 K/W. The proposed method exhibits excellent performance and provides a low-cost, highly efficient design solution for the battery module under varying conditions.

The WorldWide Antimalarial Resistance Network’s efforts to “level the playing fields” for data sharing by researchers in malaria endemic countries

The WorldWide Antimalarial Resistance Network’s efforts to “level the playing fields” for data sharing by researchers in malaria endemic countries

Dimensionless unified modelling of macroscale electric properties of conductive fibre networks in different regimes

The electric properties of conductive fibre networks, which can be representative of carbon nanotube networks, are investigated by means of numerical simulations and a dimensionless unified macroscale model is developed. Fibres are represented as rigid chains of discrete element method particles and we compress systems of fibres in a representative volume element periodic in three dimensions. In the used electric resistor network method, the particles are used as discretisation points to construct a system of linear equations linking the particle conductivities to their local electric potentials and in turn allowing for predictions on the electric macroscale properties of the fibre system. A carried out dimensional analysis suggests suitable scaling laws to unify different macroscale fibre systems in two different regimes - a percolating and a conductive regime. The dimensionless macroscale conductance is found to depend on the percolation threshold and percolation probability. It is moreover found that the critical solid volume fraction for rigid fibres is not only dependent on the fibre aspect ratio, but can also depend on the compression height of the system. Additionally, correlations between transmittance and solid volume fractions are found allowing for possibly simple solid volume fraction estimations in experiments.

Electrical properties of a generalized 2 × n resistor network

Any changes in resistor conditions will increase the difficulty of resistor network research. This paper considers a new model of a generalized 2 × n resistor network with an arbitrary intermediate axis that was previously unsolved. We investigate the potential function and equivalent resistance of the 2 × n resistor network using the RT-I theory. The RT-I method involves four main steps: (1) establishing difference equations on branch currents, (2) applying a matrix transform to study the general solution of the differential equation, (3) obtaining a current analysis of each branch according to the boundary constraints, and (4) deriving the potential function of any node of the 2 × n resistor network by matrix transformation, and the equivalent resistance formula between any nodes. The article concludes with a discussion of a series of special results, comparing and verifying the correctness of the conclusions. The work establishes a theoretical basis for related scientific research and application.

Robustness of Sparsely Distributed Representations to Adversarial Attacks in Deep Neural Networks.

Deep learning models have achieved an impressive performance in a variety of tasks, but they often suffer from overfitting and are vulnerable to adversarial attacks. Previous research has shown that dropout regularization is an effective technique that can improve model generalization and robustness. In this study, we investigate the impact of dropout regularization on the ability of neural networks to withstand adversarial attacks, as well as the degree of "functional smearing" between individual neurons in the network. Functional smearing in this context describes the phenomenon that a neuron or hidden state is involved in multiple functions at the same time. Our findings confirm that dropout regularization can enhance a network's resistance to adversarial attacks, and this effect is only observable within a specific range of dropout probabilities. Furthermore, our study reveals that dropout regularization significantly increases the distribution of functional smearing across a wide range of dropout rates. However, it is the fraction of networks with lower levels of functional smearing that exhibit greater resilience against adversarial attacks. This suggests that, even though dropout improves robustness to fooling, one should instead try to decrease functional smearing.

Variability in white blood cell count during uncomplicated malaria and implications for parasite density estimation: a WorldWide Antimalarial Resistance Network individual patient data meta-analysis

BackgroundThe World Health Organization (WHO) recommends that when peripheral malarial parasitaemia is quantified by thick film microscopy, an actual white blood cell (WBC) count from a concurrently collected blood sample is used in calculations. However, in resource-limited settings an assumed WBC count is often used instead. The aim of this study was to describe the variability in WBC count during acute uncomplicated malaria, and estimate the impact of using an assumed value of WBC on estimates of parasite density and clearance.MethodsUncomplicated malaria drug efficacy studies that measured WBC count were selected from the WorldWide Antimalarial Resistance Network data repository for an individual patient data meta-analysis of WBC counts. Regression models with random intercepts for study-site were used to assess WBC count variability at presentation and during follow-up. Inflation factors for parasitaemia density, and clearance estimates were calculated for methods using assumed WBC counts (8000 cells/µL and age-stratified values) using estimates derived from the measured WBC value as reference.ResultsEighty-four studies enrolling 27,656 patients with clinically uncomplicated malaria were included. Geometric mean WBC counts (× 1000 cells/µL) in age groups < 1, 1–4, 5–14 and ≥ 15 years were 10.5, 8.3, 7.1, 5.7 and 7.5, 7.0, 6.5, 6.0 for individuals with falciparum (n = 24,978) and vivax (n = 2678) malaria, respectively. At presentation, higher WBC counts were seen among patients with higher parasitaemia, severe anaemia and, for individuals with vivax malaria, in regions with shorter regional relapse periodicity. Among falciparum malaria patients, using an assumed WBC count of 8000 cells/µL resulted in parasite density underestimation by a median (IQR) of 26% (4–41%) in infants < 1 year old but an overestimation by 50% (16–91%) in adults aged ≥ 15 years. Use of age-stratified assumed WBC values removed systematic bias but did not improve precision of parasitaemia estimation. Imprecision of parasite clearance estimates was only affected by the within-patient WBC variability over time, and remained < 10% for 79% of patients.ConclusionsUsing an assumed WBC value for parasite density estimation from a thick smear may lead to underdiagnosis of hyperparasitaemia and could adversely affect clinical management; but does not result in clinically consequential inaccuracies in the estimation of the prevalence of prolonged parasite clearance and artemisinin resistance.

Prevalence of and risk factors for microscopic and submicroscopic malaria infections in pregnancy: a systematic review and meta-analysis

Malaria infections during pregnancy can cause adverse birth outcomes, yet many infections are undetected by microscopy. We aimed to describe the epidemiology of submicroscopic malaria infections in pregnant women in Asia, the Americas, and Africa using aggregated and individual participant data (IPD). For this systematic review and meta-analysis, studies (published Jan 1, 1997 to Nov 10, 2021) with information on both microscopic and submicroscopic infections during pregnancy from Asia, the Americas, or Africa, identified in the Malaria-in-Pregnancy Library, were eligible. Studies (or subgroups or study groups) that selected participants on the basis of the presence of fever or a positive blood smear were excluded to avoid selection bias. We obtained IPD (when available) and aggregated data. Estimates of malaria transmission intensity and sulfadoxine-pyrimethamine resistance, matched by study location and year, were obtained using publicly available data. One-stage multivariable logit and multinomial models with random intercepts for study site were used in meta-analysis to assess prevalence of and risk factors for submicroscopic infections during pregnancy and at delivery. This study is registered with PROSPERO, number CRD42015027342. The search identified 87 eligible studies, 68 (78%) of which contributed to the analyses. Of these 68 studies, 45 (66%) studies contributed IPD (48 869 participants) and 23 (34%) studies contributed aggregated data (11 863 participants). During pregnancy, median prevalence estimates were 13·5% (range 0·0-55·9, 66 substudies) for submicroscopic and 8·0% (0·0-50·6, 66 substudies) for microscopic malaria. Among women with positive Plasmodium nucleic acid amplification tests (NAATs), the median proportion of submicroscopic infections was 58·7% (range 0·0-100); this proportion was highest in the Americas (73·3%, 0·0-100), followed by Asia (67·2%, 36·4-100) and Africa (56·5%, 20·5-97·7). In individual patient data analysis, compared with women with no malaria infections, those with submicroscopic infections were more likely to present with fever in Africa (adjusted odds ratio 1·32, 95% CI 1·02-1·72; p=0·038) but not in other regions. Among women with NAAT-positive infections in Asia and the Americas, Plasmodium vivax infections were more likely to be submicroscopic than Plasmodium falciparum infections (3·69, 2·45-5·54; p<0·0001). Risk factors for submicroscopic infections among women with NAAT-positive infections in Africa included older age (age ≥30 years), multigravidity, and no HIV infection. During pregnancy, submicroscopic infections are more common than microscopic infections and are associated with fever in Africa. Malaria control in pregnancy should target both microscopic and submicroscopic infections. Bill & Melinda Gates Foundation through the Worldwide Antimalarial Resistance Network.

Experimental comparison and numerical study of flow and heat transfer characteristics of the pipe rows in heat pipe heat exchanger

Lube oil cooling is a very important heat transfer process on board, and the use of liquid-liquid heat pipe heat exchangers (HPHE) is easier to maintain and save energy, and does not have the risk of leakage. In this work, the heat transfer and flow in the heat pipe row of liquid-liquid HPHE is analyzed. The numerical model of HPHE based on the thermal resistance network of heat pipe is constructed and verified with the actual experimental data, and its maximum deviation is 8.1%. Results show that increasing the working fluid temperature in the evaporative section improved the operating performance of the heat pipe inside the HPHE, with the maximum equivalent thermal conductivity reaching 7112 W·m−1·K−1 at 70 °C. Furthermore, increasing the hot fluid flow rate improved the heat transfer rate of the HPHE more than increasing the cold fluid inlet flow rate. The convective heat transfer performance equations were fitted to the HPHE, with reliable accuracy within 5% obtained for both the forced convection correlations in the condensing and evaporating sections. The pipe row effect was observed to have some variability, with the periodic variation of the heat transfer coefficient per pipe row being more pronounced. The heat transfer coefficient of the pipe row at the outlet decreased by 15.5%, and the heat transfer coefficient of the pipe row at the baffle gap was also about 15% lower than that of the middle pipe row.

Unmasking Maps, Unmaking Empire: Towards an Archipelagic Cartography

On the surface, maps enable the planning and development of human dwelling, the visualization of connections, and drawing of boundaries. Throughout human history, however, maps have also acted as antidotes to chaos by generating spatial imaginations as pathways to meaning, belonging, and yearning. Exploring both theoretical and practical trajectories of transnational mappings, this article traces cartographies through the spatio-cultural nodes of the mainland United States, Hawaiʻi, and Micronesia. By revealing hidden connections, interstices, mobilities, memories, flows, and polysemic knowledges, it argues that an archipelagic approach to cartographic creation and interpretation reveals the significance of ‘minor’ spatial imaginations, mobilities, and historical practices. Although these may appear interspersed, fragmented, or insular, I suggest that they form nodes in archipelagic networks of resistance against colonizing cartographic regimes that aim to homogenize, police, and commodify spaces according to imperial logics—thus casting doubts on the authority of continental, national, and imperial/colonial geographic vocabularies. The article’s findings make apparent the need for a methodological turn that takes into account the methodological relationality and social agency of maps as actors in the generation and interpretation of discursive networks of spatial imaginations. Engaging with these imaginations, it becomes clear, means reevaluating and redefining conventional understandings of oceans, islands, continents, archipelagos, as well as those yet unnamed, unmapped, and unwritten places that exist between or submerged below these categories.

Pilot testing the EARS-Vet surveillance network for antibiotic resistance in bacterial pathogens from animals in the EU/EEA.

As part of the EU Joint Action on Antimicrobial Resistance (AMR) and Healthcare-Associated Infections, an initiative has been launched to build the European AMR Surveillance network in veterinary medicine (EARS-Vet). So far, activities included mapping national systems for AMR surveillance in animal bacterial pathogens, and defining the EARS-Vet objectives, scope, and standards. Drawing on these milestones, this study aimed to pilot test EARS-Vet surveillance, namely to (i) assess available data, (ii) perform cross-country analyses, and (iii) identify potential challenges and develop recommendations to improve future data collection and analysis. Eleven partners from nine EU/EEA countries participated and shared available data for the period 2016-2020, representing a total of 140,110 bacterial isolates and 1,302,389 entries (isolate-antibiotic agent combinations). Collected data were highly diverse and fragmented. Using a standardized approach and interpretation with epidemiological cut-offs, we were able to jointly analyze AMR trends of 53 combinations of animal host-bacteria-antibiotic categories of interest to EARS-Vet. This work demonstrated substantial variations of resistance levels, both among and within countries (e.g., between animal host species). Key issues at this stage include the lack of harmonization of antimicrobial susceptibility testing methods used in European surveillance systems and veterinary diagnostic laboratories, the absence of interpretation criteria for many bacteria-antibiotic combinations of interest, and the lack of data from a lot of EU/EEA countries where little or even surveillance currently exists. Still, this pilot study provides a proof-of-concept of what EARS-Vet can achieve. Results form an important basis to shape future systematic data collection and analysis.

Reversible vancomycin susceptibility within emerging ST1421 Enterococcus faecium strains is associated with rearranged vanA-gene clusters and increased vanA plasmid copy number

Vancomycin variable enterococci (VVE) are van-positive enterococci with a vancomycin-susceptible phenotype (VVE-S) that can convert to a resistant phenotype (VVE-R) and be selected for during vancomycin exposure. VVE-R outbreaks have been reported in Canada and Scandinavian countries. The aim of this study was to examine the presence of VVE in whole genome sequenced (WGS) Australian bacteremia Enterococcus faecium (Efm) isolates collected through the Australian Group on Antimicrobial resistance (AGAR) network. Eight potential VVEAus isolates, all identified as Efm ST1421, were selected based on the presence of vanA and a vancomycin-susceptible phenotype. During vancomycin selection, two potential VVE-S harboring intact vanHAX genes, but lacking the prototypic vanRS and vanZ genes, reverted to a resistant phenotype (VVEAus-R). Spontaneous VVEAus-R reversion occurred at a frequency of 4-6 × 10−8 resistant colonies per parent cell in vitro after 48 h and led to high-level vancomycin and teicoplanin resistance. The S to R reversion was associated with a 44-bp deletion in the vanHAX promoter region and an increased vanA plasmid copy number. The deletion in the vanHAX promoter region enables an alternative constitutive promoter for the expression of vanHAX. Acquisition of vancomycin resistance was associated with a low fitness cost compared with the corresponding VVEAus-S isolate. The relative proportion of VVEAus-R vs. VVEAus-S decreased over time in serial passages without vancomycin selection. Efm ST1421 is one of the predominant VanA-Efm multilocus sequence types found across most regions of Australia, and has also been associated with a major prolonged VVE outbreak in Danish hospitals.

Electrical performance of the 3 × 6 × n cobweb cascade resistance network

SummaryIn this paper, a kind of multi‐stage cobweb resistance network consisting of n single‐stage cobwebs, namely, a 3 × 6 × n cobweb cascade resistance network (CCRN), was studied. To calculate the equivalent resistance of such a large‐scale complex network, we used a modified recursion‐transform (MRT) method. Firstly, the resistance network to be solved was simplified to a simple equivalent network. Thereafter, the recursive relation of the equivalent network was established according to the basic law of circuit. Then, the nonlinear recursive relation was transformed into the linear recursive relation by variable transformation technique. Finally, the equivalent resistance was gained by resolving the linear recursive relation. By this method, we obtained the exact analytical expression of the equivalent resistance of the 3 × 6 × n CCRN. The computation results show that the 3 × 6 × n CCRN's equivalent resistance is decided by the number of circuit stages n, and as n goes to infinity, these equivalent resistances all tend to a definite limit value.

Lattice Green/Neumann function for the 2D Laplacian operator defined on square lattice on cylinders, tori and other geometries with some applications

The lattice Green functions for the discrete planar Laplacian defined on regular square lattice wrapped around cylinders and tori are rigorously defined and obtained in an exact analytic form. The method of images well-known in potential theory is implemented to derive for many other geometries with free boundaries (semi-infinite or finite cylinders and strips, rectangle) the related exact lattice Green-Neumann functions needed to readily solve discrete Neumann problems or, via a Neumann-to-Dirichlet mapping, discrete Dirichlet problems for these flat square lattices. Some applications are thus proposed as explicit expressions of two-point resistances for related resistor networks, and some probability-based characteristics regarding the associated Pòlya’s random walks.

Tiling of rectangles with squares and related problems via Diophantine approximation

This article shines new light on the classical problem of tiling rectangles with squares efficiently with a novel method. With a twist on the traditional approach of resistor networks, we provide new and improved results on the matter using the theory of Diophantine Approximation, hence overcoming long-established difficulties, such as generalizations to higher-dimensional analogues. The universality of the method is demonstrated through its applications to different tiling problems. These include tiling rectangles with other rectangles, with their respective higher-dimensional counterparts, as well as tiling equilateral triangles, parallelograms, and trapezoids with equilateral triangles.

Improving the Sierpinski carpet model arithmetic to accurately predict the thermal conductivity of fatty acid/carbon composite phase-change materials

The effective thermal conductivity is an important physical parameter of composite phase-change materials (PCMs). In this study, a new analytic expression of the dimensionless thermal conductivity is proposed to predict the dimensionless thermal conductivity of fatty acid–carbon materials composite PCMs based on the Sierpinski carpet model and the thermal resistance network model of a fractal geometry combined with the principle of the weighted average. The new analytical expression can be used to overcome the issue of the predicted values deviating considerably from the experimental results when the fractal series n is too small. At the same time, an accurate solution for the dimensionless ratio (t+) of the width of the carbon materials to the side length of the Sierpinski carpet is presented. Compared with the general solution algorithm proposed by Song, the commonly used quadratic parallel (QP) prediction model, and the Maxwell–Eucken model, this algorithm is more reliable. The proposed prediction model can be used to predict the effective thermal conductivity of fatty acid–carbon materials.

PARAMETRICAL SYNTHESIS OF PEAK-PHASE MODULATORS WITH THE SET QUANTITY OF IDENTICAL CASCADES OF TYPE «THE NONLINEAR PART – THE RESISTIVE TWO-PORT NETWORK»

Resistive elements possess independence of their resistance from frequency in a very wide band of frequencies. Therefore, developing algorithms of parametrical synthesis of amplitude-phase modulators with the use of resistive matching four-pole networks is an actual task. In this work, matching provides the set dependence of a relation of modules and a difference of transfer function phases from frequency in two conditions of a nonlinear element defined by two levels of a control signal. The nonlinear part represents a three-pole nonlinear element with a feedback. The interrelations between elements of the classical matrix of transferring in four-pole networks are established, and the formulas for defining resistances of their two-pole units that are optimum by the criterion of amplitude-phase modulation of an outputt signal are determined. The theory of four-pole networks, as well as the methods of matrix algebra, parametrical synthesis of UHF control devices, decomposition and circuit analysis of radio devices are used. The comparative analysis of theoretical results (AFC and PFC of modulators in two states) received by mathematical modelling in the «MathCad» system and of experimental results received by circuit simulation in the «OrCad» and «MicroCap» systems shows their satisfactory coincidence.

Analytical potential formulae and fast algorithm for a horn torus resistor network.

In this paper, a (u+1)×v horn torus resistor network with a special boundary is researched. According to Kirchhoff's law and the recursion-transform method, a model of the resistor network is established by the voltage V and a perturbed tridiagonal Toeplitz matrix. We obtain the exact potential formula of a horn torus resistor network. First, the orthogonal matrix transformation is constructed to obtain the eigenvalues and eigenvectors of this perturbed tridiagonal Toeplitz matrix; second, the solution of the node voltage is given by using the famous fifth kind of discrete sine transform (DST-V). We introduce Chebyshev polynomials to represent the exact potential formula. In addition, the equivalent resistance formulae in special cases are given and displayed by a three-dimensional dynamic view. Finally, a fast algorithm of computing potential is proposed by using the mathematical model, famous DST-V, and fast matrix-vector multiplication. The exact potential formula and the proposed fast algorithm realize large-scale fast and efficient operation for a (u+1)×v horn torus resistor network, respectively.

Deterministic Conductive Filament Formation and Evolution for Improved Switching Uniformity in Embedded Metal-Oxide-Based Memristors─A Phase-Field Study

The extreme device-to-device variation of switching performance is one of the major obstacles preventing the applications of metal-oxide-based memristors in large-scale memory storage and resistive neural networks. Recent experimental works have reported that embedding metal nano-islands (NIs) in metal oxides can effectively improve the uniformity of the memristors, but the underlying role of the NIs is not fully understood. Here, to address this specific problem, we develop a physical model to understand the origin of the variability and how the embedded NIs can improve the performance and uniformity of memristors. We find that due to the dimension confinement effect, embedding metal NIs can modulate the electric field distribution and lead to a more deterministic formation of the conductive filament (CF) from their vicinity, in contrast to the random growth of CFs without embedded NIs. This deterministic CF formation, via vacancy nucleation, further reduces the forming, reset, and set voltages and enhances the uniformity of the operation voltages and current ON/OFF ratios. We further demonstrate that modifying the shapes of the metal NIs can modulate the field strengths/distributions around the NIs and that choosing the NI metal composition and shape that chemically facilitate vacancy formations can further optimize the CF morphology, reduce the operation voltages, and improve the switching performance. Our work thus provides a fundamental understanding of how embedded metal NIs improve the resistive switching performance in oxide-based memristors and could potentially guide the selection of embedded NIs to realize a more uniform memristor that also operates at a higher efficiency than present materials.