Simply-connected Research Articles

Local uniqueness of vortices for 2D steady Euler flow in a bounded domain

We study the 2D Euler equation in a bounded simply-connected domain, and establish the local uniqueness of flow whose stream function ψε satisfies{−ε2Δψε=∑i=1k1Bδ(z0,i)(ψε−με,i)+γ,inΩ,ψε=0,on∂Ω, with ε→0+ the scale parameter of vortices, γ∈(0,∞), Ω⊂R2 a bounded simply connected Lipschitz domain, z0,i∈Ω the limiting location of ith vortex, and με,i the flux constants unprescribed. Our proof is achieved by a detailed description of asymptotic behavior for ψε and Pohozaev identity technique. For k=1, we prove the nonlinear stability of corresponding vorticity in Lp norm, provided that z0,1 is a non-degenerate minimum point of Robin function. This stability result can be generalized to the case k≥2, and (z0,1,⋯,z0,k)∈Ωk being a non-degenerate minimum point of the Kirchhoff-Routh function.

Evaluation of HMIPv6 Algorithm in 5G Mmwave Single and Dual Connectivity Handover Network

In this article, we analyzed a Handover Mobile IPv6 (HMIPv6) algorithm under conditions of 5G millimeter wave (mmWave) single and dual connectivity. A single connectivity enables handover between 5G base stations. Meanwhile, a dual connectivity is a handover occurred from a 4G base station to a 5G base station. In sending data, TCP has a congestion control algorithm that allows TCP to handle any congestion problems on the network. In this article, we analyzed the HMIPv6 performance using TCP YeAH and TCP CUBIC with various user equipment (UE) speeds. It showed that each TCP had a fairly stable delay and throughput under the condition of the single connectivity handover with an average delay of 192.8196 ms and average throughput of 52.8812 Mb/s. Whereas, in the dual connectivity handover condition, each TCP had a fluctuating delay and throughput directly proportional to the increasing UE speed. Therefore, TCP YeAH dominated the stability in dual connectivity with an average delay of 221.4226 ms and average throughput of 44.4004 Mb/s. Overall, this article found that TCP YeAH performed better than TCP CUBIC in both the single connectivity and dual connectivity handovers.

Continuity Criterion for Locally Bounded Finite-Dimensional Representations of Simply Connected Solvable Lie Groups

Continuity Criterion for Locally Bounded Finite-Dimensional Representations of Simply Connected Solvable Lie Groups

Numerical study on split base plate connection with concentric anchors between steel‐plate composite wall and concrete basemat

SummarySteel‐plate composite (SC) walls can be connected to a concrete basemat using a base plate and a set of anchors eccentric to the wall. The base plate can be separated into two parts so that the concrete of the wall and basemat is cohesive, and thus, the wall can be manufactured more easily and economically. Additionally, compression and shear demand are directly transferred from infill concrete to concrete basemat. Another change in the base plate connection of available tested walls involves transferring anchors to the bottom of faceplates. As a result of this modification, the base plate is removed from the force transmission chain, and the force is transferred directly from the wall to the anchors. After presenting the design criteria for this type of connection, three test walls with concrete foundations were verified in LS‐Dyna. The walls were modeled with a split base plate connection and concentric anchors, and then compared to other types of wall‐basemat connections. Three rectangular sections were then chosen as benchmarks and modeled with three anchors of different sizes to evaluate the effect of this parameter on walls behavior. The design equations presented for the single base plate connection were found applicable to design split base plate connections. Then all walls were compared to the test wall‐fixed base wall connection. Finally, the models were analyzed with elastic walls to determine whether the foundation is stronger than the wall. The split base plate connection with concentric anchors was found to be stronger than connected parts and can be an alternative to existing connections.

Design Synthesis of a Robotic Uniaxial Torque Device for Orthopedic Haptic Simulation

Abstract Robotic devices are commonly used in surgical simulators to provide tactile, or haptic, feedback. They can provide customized feedback that can be rapidly modified with minimal hardware changes in comparison to nonrobotic systems. This work describes the design, development, and evaluation of one such tool: a novel uniaxial torque haptic device for a surgical training simulator. The objective of the work was to design a single connection haptic device that could augment an existing six degree-of-freedom haptic device to mimic a Concorde Clear vacuum curette. Design and evaluations focused on the tool's ability to deliver adequate torque, imitate a surgical tool, and be integrated into the haptic device. Twenty-nine surgeons tested the tool in the simulator and evaluated it via a questionnaire. The device was found to deliver the 800 N⋅mm of torque necessary to mimic an orthopedic procedure. Surgeons found it accurately imitated surgical tools physical appearance and maneuverability, scoring them 3.9 ± 1.0 and 3.3 ± 1.2, respectively, on a 1–5 Likert scale. By virtue of the functionality necessary for testing and evaluation, the device could be connected to the haptic device for mechanical and electrical engagement. This device is a step forward in the field of augmentable haptic devices for surgical simulation. By changing the number of robotically controlled degrees-of-freedom of a haptic device, existing devices can be tuned to meet the demands of a particular simulator, which has the potential to improve surgeon training standards.

Enhanced Sensory Identification in Arrays of Coupled Resonant Sensors

Coupled resonant sensors have been used in a large number of sensing systems with microelectromechanical systems, enabling multi-sensing using single input-output connections as one can record the collective behaviour of an array of coupled resonant sensors using the response of only one of their elements. The forward problem with these systems is to identify the change in eigenvalues recorded when some sensing operation takes place, which often reflects as a eigenvalue perturbation problem. The reverse problem of identifying the sensing element and the sensing amount is challenging, when recording only one readout in such systems. This paper provides a robust new technique to do so with enhanced accuracy and noise tolerance. This is achieved by using properties of eigenpairs and an inverse analysis. The method has been verified using experimental data from an array of coupled microelectromechanical resonators. The technique has also been analysed for potential experimental errors including quantisation and random noises.

IEEE Publications: How Do We Measure Success? [From the Editor’s Desk

At this very moment, you have made the decision to commit time in your day to read through the latest issue of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">IEEE Industry Applications Magazine</i> . A good choice … and I thank you. For more than 14,000 IEEE Industry Applications Society (IAS) members around the globe, this magazine is the single common connection—for many, the only connection—to our Society and to IEEE. Remarkably, IEEE publishes 377 periodicals, including newsletters, journals, transactions, and magazines. How do <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">IEEE Industry Applications Magazine</i> and other IAS publications stack up against the rest of the IEEE periodicals, and how do we know if we’re doing things right? Likely, you have never considered these questions. There are people who do.

Localization and diagnosis of abnormal channels in children with ASD based on WMSSE and ASI

BackgroundThe purpose of this study is to explore the differences of resting EEG in children with autism spectrum disorders and then analyze the sensitive channels with significant differences, to provide support for the accurate differential diagnosis of autism spectrum disorder (ASD). New methodBased on the weighted multi-scale sample entropy (WMSSE) algorithm and amplitude synchronization index (ASI) algorithm of EEG, this paper comprehensively evaluates the brain state of ASD children from the two aspects of brain function complexity and brain function synchronization connectivity. Further, by combining the support vector machine (SVM) classification model to explore the location of abnormal channels of ASD children and realize the diagnosis of ASD children. ResultsThe WMSSE of the ASD group was lower than that of the healthy group. Furthermore, there was a significant difference in the F3/F4 channels and F7/F8 channels (P < 0.05), and the synchronization of the brain in the ASD group was also lower than that of the healthy group in Delta, Theta, Alpha, Beta band. Finally, combined with the WMSSE and ASI features of the F3/F4 channels (posterior frontal lobe) and F7/F8 channels (anterior temporal lobe), the classification accuracy and AUC value of ASD patients calculated by the SVM classification model were 82.7 ± 3.2%/ 0.795 (F3 / F4 channels), 89.8 ± 1.7%/ 0.812 (F7 / F8 channels). Comparison with existing methodsIt avoids the one-sided problem of single analysis complexity and synchronous connectivity, and provides a research basis for the comprehensive evaluation of ASD brain function. ConclusionWMSSE and ASI can be used as effective potential biomarkers for ASD diagnosis, and F7 and F8 channels can be preliminarily located as abnormal sensitive channels for ASD brain regulation. It also proves that the feature analysis of comprehensive complexity and synchronous connectivity is more conducive to the abnormal diagnosis of ASD patients.

A serviceability investigation of dowel-type timber connections featuring single softwood dowels

Dowel-type connections are common in timber engineering, but current design codes are largely based on empiricism and are oversimplified. This inhibits the optimised use of connections, which is essential for the design of economically efficient timber structures. This study investigates the use of 3D computational modelling to predict the slip modulus (a key measure of stiffness) of single and double shear, dowel-type connections featuring a single softwood dowel. Initial modelling was conducted on parallel- and perpendicular-to-grain connections to establish a suitable mesh size and to validate the model against experimental work. The slip modulus in angled orientations was then investigated, a relationship given no consideration in design codes. The results show that the current design codes greatly overestimate the slip modulus in both single and double shear connections involving timber dowels. In comparison, the models in this study are more than twice as accurate at predicting slip modulus. Furthermore, slip modulus was shown to vary sinusoidally as the grain-to-grain angle changes between the parallel and perpendicular orientations. Differences between model and experimental values can be attributed to uncertainty in the mechanical properties of the timber in the experiments, the assumption of uniform properties for timber in each principal direction in the models, and the inherent variability of timber which affects experimental results.

Dual-Resonance (16/32 MHz) Piezoelectric Transducer With a Single Electrical Connection for Forward-Viewing Robotic Guidewire.

Peripheral artery disease (PAD) affects more than 200 million people globally. Minimally invasive endovascular procedures can provide relief and salvage limbs while reducing injury rates and recovery times. Unfortunately, when a calcified chronic total occlusion is encountered, ~25% of endovascular procedures fail due to the inability to advance a guidewire using the view provided by fluoroscopy. To enable a sub-millimeter, robotically steerable guidewire to cross these occlusions, a novel single-element, dual-band transducer is developed that provides simultaneous multifrequency, forward-viewing imaging with high penetration depth and high spatial resolution while requiring only a single electrical connection. The design, fabrication, and acoustic characterization of this device are described, and proof-of-concept imaging is demonstrated in an ex vivo porcine artery after integration with a robotically steered guidewire. Measured center frequencies of the developed transducer were 16 and 32 MHz, with -6 dB fractional bandwidths of 73% and 23%, respectively. When imaging a 0.2-mm wire target at a depth of 5 mm, measured -6 dB target widths were 0.498 ± 0.02 and 0.268 ± 0.01 mm for images formed at 16 and 32 MHz, respectively. Measured SNR values were 33.3 and 21.3 dB, respectively. The 3-D images of the ex vivo artery demonstrate high penetration for visualizing vessel morphology at 16 MHz and ability to resolve small features close to the transducer at 32 MHz. Using images acquired simultaneously at both frequencies as part of an integrated forward-viewing, guidewire-based imaging system, an interventionalist could visualize the best path for advancing the guidewire to improve outcomes for patients with PAD.

Investigation and standardisation of electrolysers for green hydrogen production using the test infrastructure in Bremerhaven, Germany

Abstract To realise the installation targets of 10 GW electrolysis capacity in Germany and 40 GW in the EU until 2030, extensive standardisation and testing is required. The electrical characteristics of electrolysers need to be fully understood and mastered for a reliable operation within distribution grids and decoupled grids of systems to produce green hydrogen, e.g. off-shore. Using a modular test infrastructure and multi-functional test pads, electrolysers, but also fuel cells and CHP units, can be tested in emulated grid conditions. To emphasize the range of feasibility regarding testing, three different scenarios were developed, covering the challenges between single unit grid connection and offshore hydrogen production. The test results serve as input for standardisation committees to expand existing and develop new guidelines.

Static performance of steel temcor joint subjected to out-of-plane bending moments

The temcor system is one of the most famous single-layer grid shell structures’ connections. In this study, temcor joints were designed using Q345 steel with Huck bolts instead of the aluminium alloy to expand using an H-shaped beam of steel in single-layer grid shell structures. Twenty-two joints with a single Huck bolt connection were designed and tested to investigate the shear strength of Huck bolts. At the same time, three specimens of steel temcor joint (TC1, TC2, and TC3) were designed considering the number of Huck bolts, the thickness of the gusset plates, and material type. FE models for tested joints were established using Abaqus to conduct numerical and parametrical analyses. The experimental and numerical results indicated that the bending capacity and the stiffness of the steel temcor joint were limited increased by increasing the gusset plate thickness. However, when the thickness of gusset plates exceeded the thickness of the flanges of the H-shaped beam, the main failure occurred on the H-shaped beam. However, those joints’ stiffness and bending capacity stopped increasing.Moreover, the bending capacity and stiffness of steel temcor joints were higher than that of aluminium temcor joints by an average of 177% and 180%, respectively. The theoretical solution for the bending capacity of steel temcor joint was proposed, and their stiffness was calculated based on Eurocode 3. Finally, the bending capacity and stiffness of the temcor joints obtained from FE models and theoretical equations were in good agreement with the experimental data.

Power-actuated fasteners in single shear-An experimental investigation and proposed design rules

This paper presents the results of 81 experimental tests on the design strength of power-actuated fasteners (PAFs) in single shear connections for a light gauge steel framing (LGSF), as an alternative to self-drilling screws for selective uses. This type of connection can be employed to install a reinforcing plate on one or both sides of the frame, to connect steel strap cross bracing to framing, as well as for many other applications. These power-actuated fasteners present a very efficient and practical solution which can increase productivity and work quality by replacing time consuming screw connections. In this study, two different steel grades (G300 and G550), along with three different steel sheet configurations were investigated. Modes of failure for both the PAFs and the connected material were examined so to provide an understanding of the structural performance of nailed single lap connections and develop design recommendations and proposed formulae. The investigation covers a wide range of steel gauges (0.75 mm, 0.95 mm and 1.15 mm), commonly used in LGSF residential and commercial applications. Two groups of tests were performed. The first group of tests was conducted to determine the shear strength of connectors with two types being tested. The second tests series were carried out in various steel grade and gauge configurations for assembled connections. The results of this research and the proposed design formula can be used to establish the strength prediction model for power-actuated fasteners (PAFs) embedded into LGSF.

Experimental field study on a full-scale road piezoelectric energy harvester

We designed a full-scale road piezoelectric energy harvester (FPEH) and performed field tests to evaluate its electrical performance under various traffic loads. Based on the open-circuit voltage waveform of the FPEH, its electrical output characteristics were established given different axle loads and vehicle speeds. New circuits were designed that can be used to identify the wheel track and wheel position of the vehicle and to determine the horizontal transfer characteristics of the vehicle vibration energy on the road surface. Two off-board circuits were designed for different applications of the FPEH. A parallel circuit rectifies 192 transducer units separately and then connects them in parallel. At a resistance load of 0.4 kΩ, vehicle speed of 60 km h−1, and axle load of 1295 kg, this circuit generated a maximum output of 42 V, 104 mA, and 4338 mW. A single connection circuit rectifies eight transducer units separately and then connects them in parallel to form a total of 24 groups. The electrical performance was evaluated though finite element analyses and field tests. This research is the first to design and fully characterize the electrical performance of a FPEH. The proposed FPEH design significantly improves the driving-load vibration energy harvesting efficiency and produces a watt-level output which is a higher energy output than prior research. The findings obtained herein provide a good foundation for the application of road piezoelectric power generation technology.

Hidden transition in multiplex networks

Weak multiplex percolation generalizes percolation to multi-layer networks, represented as networks with a common set of nodes linked by multiple types (colors) of edges. We report a novel discontinuous phase transition in this problem. This anomalous transition occurs in networks of three or more layers without unconnected nodes, P(0),=,0. Above a critical value of a control parameter, the removal of a tiny fraction Delta of nodes or edges triggers a failure cascade which ends either with the total collapse of the network, or a return to stability with the system essentially intact. The discontinuity is not accompanied by any singularity of the giant component, in contrast to the discontinuous hybrid transition which usually appears in such problems. The control parameter is the fraction of nodes in each layer with a single connection, Pi ,=,P(1). We obtain asymptotic expressions for the collapse time and relaxation time, above and below the critical point Pi _c, respectively. In the limit Delta rightarrow 0 the total collapse for Pi ,>,Pi _text {c} takes a time T propto 1/(Pi -Pi _text {c}), while there is an exponential relaxation below Pi _text {c} with a relaxation time tau propto 1/[Pi _text {c}-Pi ].

An ensemble of Xgboost models for detecting disorders of consciousness in brain injuries through EEG connectivity

Disorders of consciousness (DoC) happen frequently in brain injuries. Automated DoC detection is desirable because conventional clinical examinations, typically behavioural assessments, consume significant resources of manpower and time. Extracting knowledge from electroencephalogram (EEG) signals and then employing machine learning to classify patients are an attractive way to achieve automatic detection of DoC. However, an EEG dataset from brain injuries always has much more subjects without DoC than the subjects with DoC. Because of the heavy imbalance of the dataset, even if the re-sampling technique is used, it is still challenging to achieve good classification performance from, e.g., eXtreme Gradient Boosting (Xgboost), one of the most effective machine learning methods. This paper develops an ensemble of multiple Xgboost models (EoXgboost) to improve the machine learning performance for DoC detection in the presence of severe class distribution skews. We also explore effective connectivity indices to distinguish brain injuries with and without DoC. A new combined connectivity measure is shown to be effective in detecting DoC in a dataset of 648 brain injuries. Our classification results show that our EoXgboost classifier with the new combined connectivity index has achieved the best classification performance than the single connectivity indices. Our EoXgboost has detected DoC in brain injuries with the accuracy of 99.07%, AUC of 98.74%, specificity of 99.77%, and sensitivity of 97.71%. This demonstrates that our EoXgboost is a promising tool for DoC detection in brain injuries.

Convergent and Divergent Structural Connectivity of Brain White Matter Network Between Patients With Erectile Dysfunction and Premature Ejaculation: A Graph Theory Analysis Study.

BackgroundSexual dysfunction, namely, erectile dysfunction (ED) and premature ejaculation (PE), has been found to be associated with abnormal structural connectivity in the brain. Previous studies have mainly focused on a single disorder, however, convergent and divergent structural connectivity patterns of the brain network between ED and PE remain poorly understood.MethodsT1-weighted structural data and diffusion tensor imaging data of 28 patients with psychological ED, 28 patients with lifelong PE (LPE), and 28 healthy controls (HCs) were obtained to map the white matter (WM) brain networks. Then, the graph-theoretical method was applied to investigate the differences of network properties (small-world measures) of the WM network between patients with ED and LPE. Furthermore, nodal segregative and integrative parameters (nodal clustering coefficient and characteristic path length) were also explored between these patients.ResultsSmall-world architecture of the brain networks were identified for both psychological ED and LPE groups. However, patients with ED exhibited increased average characteristic path length of the brain network when compared with patients with LPE and HCs. No significant difference was found in the average characteristic path length between patients with LPE and HCs. Moreover, increased nodal characteristic path length was found in the right middle frontal gyrus (orbital part) of patients with ED and LPE when compared with HCs. In addition, patients with ED had increased nodal characteristic path length in the right middle frontal gyrus (orbital part) when compared with patients with LPE.ConclusionTogether, our results demonstrated that decreased integration of the right middle frontal gyrus (orbital part) might be a convergent neuropathological basis for both psychological ED and LPE. In addition, patients with ED also exhibited decreased integration in the whole WM brain network, which was not found in patients with LPE. Therefore, altered integration of the whole brain network might be the divergent structural connectivity patterns for psychological ED and LPE.

High-frequency oscillations and sequence generation in two-population models of hippocampal region CA1.

Hippocampal sharp wave/ripple oscillations are a prominent pattern of collective activity, which consists of a strong overall increase of activity with superimposed (140 − 200 Hz) ripple oscillations. Despite its prominence and its experimentally demonstrated importance for memory consolidation, the mechanisms underlying its generation are to date not understood. Several models assume that recurrent networks of inhibitory cells alone can explain the generation and main characteristics of the ripple oscillations. Recent experiments, however, indicate that in addition to inhibitory basket cells, the pattern requires in vivo the activity of the local population of excitatory pyramidal cells. Here, we study a model for networks in the hippocampal region CA1 incorporating such a local excitatory population of pyramidal neurons. We start by investigating its ability to generate ripple oscillations using extensive simulations. Using biologically plausible parameters, we find that short pulses of external excitation triggering excitatory cell spiking are required for sharp/wave ripple generation with oscillation patterns similar to in vivo observations. Our model has plausible values for single neuron, synapse and connectivity parameters, random connectivity and no strong feedforward drive to the inhibitory population. Specifically, whereas temporally broad excitation can lead to high-frequency oscillations in the ripple range, sparse pyramidal cell activity is only obtained with pulse-like external CA3 excitation. Further simulations indicate that such short pulses could originate from dendritic spikes in the apical or basal dendrites of CA1 pyramidal cells, which are triggered by coincident spike arrivals from hippocampal region CA3. Finally we show that replay of sequences by pyramidal neurons and ripple oscillations can arise intrinsically in CA1 due to structured connectivity that gives rise to alternating excitatory pulse and inhibitory gap coding; the latter denotes phases of silence in specific basket cell groups, which induce selective disinhibition of groups of pyramidal neurons. This general mechanism for sequence generation leads to sparse pyramidal cell and dense basket cell spiking, does not rely on synfire chain-like feedforward excitation and may be relevant for other brain regions as well.

Bearing-strength of paper laminates in single bolt connections

This study is the first step of a research program organized to contribute to the dream of using recycled paper as a structural element for sustainable design in Civil Engineering. One of the important tasks is to understand the behavior of connections in paper materials. This study presents the results of experimental research carried out to investigate the behavior of paperboard laminate connections consisting of a single bolt in double shear. A simple and effective method to predict the bearing strength in bolted connection for paperboard laminates has been proposed. A total of 96 bolted connections were fabricated from paperboards oriented in both machine and cross direction. The effect of end distance and edge distance of bolt hole are investigated to address the limiting value for both variables. It was found that the failure is governed by both shear and bearing stresses developed around the hole. Finally, a straightforward design equation has been proposed for such connections.

Design of various parts of multi-joint bionic fish equipment

The multi-joint bionic fish has a convenient and stable structure, small size, and can be used in different occasions. At present, it can be used in normal underwater activities and can effectively solve the difficult problem of underwater exploration. The equipment consists of six parts in total: fish wing forward device, fish wing movement linkage device, single joint connection device, fish tail stabilization device, fish body bending and direction changing device, and driving device. Satisfying the basic requirements can solve the problem of underwater operations.