Simply-connected Research Articles

Research on the optimisation of logistics parcel intelligent sorting and conveying chain combined with variable clustering mathematical method

Abstract The rapid development of China’s economy, especially the rapid rise of the logistics and distribution industry in recent years, coupled with the rise of e-commerce in recent years, has created a huge impact on the traditional logistics industry. Aiming at the sorting system of small and medium-sized logistics distribution centrer, this paper proposes an item allocation strategy based on customer demand in combination with practical application requirements and adopts the direct dynamic clustering algorithm based on hierarchical clustering. As a clustering index, all items in the distribution centre are clustered and the final clustering result is obtained. The results show that the maximum value of segmentation using the single connection method is 5.8, reflecting that the distribution distance is more advantageous; the maximum value of the segmentation method using the median method is 2.94, and the minimum value is 2.35, which reflects that the result of the algorithm is relatively uniform. A reasonable item allocation strategy has a certain positive effect and influence on the development of modern logistics and the service quality of the logistics industry.

Application of electrical power measurements for process monitoring in ultrasonic metal welding

For the production of e-mobility components such as cable harnesses, battery cells, power electronics, etc., ultrasonic metal welding is well-established process of choice. These electrical applications require high quality for every single connection; single points of failure and no possibility of repair after installation or commissioning are state of the art. At present, the prevailing binding mechanisms and their sensitivity to the numerous process influencing variables like base material hardness, surface, and cleanliness are still the subject of research. In order to ensure sufficient quality despite the lack of process understanding, random destructive testing is carried out during ongoing production. The welding systems’ internal monitoring methods are currently not sufficient to make a prediction of the joint quality achieved. To determine process phases and extract features regarding the joint formation, the observation of process vibrations at the horn, anvil, and the components using laser-doppler-vibrometry, laser triangulation sensors or other suitable external measurement technology is common. These methods require external accessibility to the measurement position, not given in the industrial production environment. In this study, measurements of the high-frequency power signal of the welding system are conducted, and several machine learning models for quality prediction are set up. To ensure the robustness, several disturbances, e.g., changing material hardness and cleanliness, are taken into account. Thus, it will be evaluated to what extent an industrially suitable quality monitoring can be implemented by means of electrical measuring technology and how much more accurate such an external measuring system is compared to the possibilities already available in the welding system.

Virtual Dynamic Grid Impedance and Its Impacts on Harmonics and Stability of Inverter Based Resources Plant

Nowadays, a large number of inverter-based resources (IBRs) are integrated into the grid at a single connection point as an IBR plant. In this article, a virtual dynamic grid impedance concept is introduced to evaluate the harmonics and stability for grid integration of an IBR plant containing multiple IBRs. First, a detailed theoretical study is conducted to build a foundation of the virtual grid impedance concept, which is a dynamic impedance that changes with the number of IBRs added into an IBR plant. Then, based on the new virtual dynamic grid impedance concept, frequency spectrum analysis is performed to explore harmonic impact at the interconnection point for an IBR plant with IBRs having L, LC, and LCL filters, respectively. An electromagnetic transient (EMT) simulation model of a grid-connected IBR plant is developed to explore the harmonics and stability of the IBR plant connected to the grid as well as the reliable operation of IBRs within the plant from the novel virtual equivalent dynamic grid impedance point of view. Hardware experiments are conducted to validate the EMT simulation evaluation. The results show that the number of IBRs added into an IBR plant influences the grid impedance, i.e., grid strength, and the grid impedance variation has multiple impacts on the IBR plant and IBRs within the plant depending on the grid-connected filters of the IBRs.

A five-primary Maxwellian-view display for independent control of melanopsin, rhodopsin, and three-cone opsins on a fine spatial scale.

Independent spatiotemporal control of the stimulation of the five photoreceptor classes requires a display with as many primary lights to probe their isolated spatial and temporal responses. No such system exists with suitable performance properties. We present a system to construct a five-primary display from commercially available three-primary digital light processing projectors. It optimizes the set of five primary lights required to maximize the achievable contrast of a single photoreceptor class in a silent substitution protocol, including where the background chromaticity is first specified. From these chosen five primaries, we describe a method to convert complex three-primary (RGB) images to five-primary representations with complete specification of the photoreceptor excitations at each pixel. Key to enabling this multiple display system with a single HDMI connection is a novel control protocol implemented in a deterministic field-programmable gate array controller that splits the data into five video streams to allow nearly synchronous presentation of primary image data through multiple displays. Each pixel is controlled over 9.5 bits for each primary over a single frame for measurement of threshold-level vision. In addition to a large contrast gamut, the Maxwellian view offers high retinal illumination to support the investigation of five opsin-based responses to complex spatiotemporal images with a truly silent substitution protocol, while avoiding the confounding effects of uncontrolled photoreceptor excitations as occurs in four-primary systems. The customizable primaries facilitate this display translation to species with different photoreceptor spectral responses, and the optics are designed for integration into microscopes for use as a stimulus generator in physiological experiments.

Harmonic Beltrami Signature: A Novel 2D Shape Representation for Object Classification

There is a growing interest in shape analysis in recent years. We present a novel shape signature for 2D bounded simply-connected domains, named the Harmonic Beltrami signature (HBS). The proposed signature is based on the harmonic extension of the conformal welding map of a unit circle and its Beltrami coefficient. We show that there is a one-to-one correspondence between the quotient space of HBS and the space of 2D simply-connected shapes up to a translation, rotation and scaling. With a suitable normalization, each equivalence class in the quotient space of HBS is associated to a unique representative. It gets rid of the conformal ambiguity. As such, each shape is associated to a unique HBS. Conversely, the associated shape of a HBS can be reconstructed based on quasiconformal Teichmuller theories, which is uniquely determined up to a translation, rotation and scaling. The HBS is thus an effective fingerprint to represent a 2D shape. The robustness of HBS is studied both theoretically and experimentally. With the HBS, simple metric, such as L2, can be used to measure geometric dissimilarity between shapes. Experiments have been carried out to classify shapes in different classes using HBS. Results show good classification performance, which demonstrate the efficacy of our proposed shape signature.

Fatigue Damage Mitigation for Welded Beam-to-Column Connections in Steel High-Rise Buildings Using Passive Vibration Control

To investigate the use of vibration control systems in fatigue damage mitigation for welded beam-to-column connections in steel high-rise buildings, cases of both a single connection under constant amplitude cyclic loading and multi-connections in a high-rise building under the stochastic wind, with and without the fluid viscous damper (VFD) and the tuned mass damper (TMD), are discussed respectively. The finite element analysis and the fatigue assessment are conducted so that the mitigation effect, the effect of technical parameters and the conditions of both high-cycle fatigue and low-cycle fatigue are all discussed. The results show that the VFD and the TMD systems are both effective in the mitigation of local fatigue damage along with the structural displacement for both cases. The VFD generally has a better mitigation effect than the TMD and it starts to take effect instantly with the external loading, but it causes a phase difference in structural responses, while the situation of the TMD is quite the opposite. The displacement and the local stress show similar and synchronous mitigation trends so that the damping systems can be designed based on either of them. The VFD should be designed with a smaller damping exponent and a larger damping coefficient in a braced installation form, while the TMD can be designed using the optimal parameters. The optimized VFD layout plan is that VFDs are placed between the two connections with large relative displacement and relative velocity on higher floors and these two connections with VFDs should be near to the targeted connection. The negative fatigue damage mitigation mainly stems from insufficient lateral support force so that the direct installation of VFDs may result in a negative fatigue damage mitigation effect in the connections with limited lateral support.

Discovering sex and age implicator edges in the human connectome

Determining important vertices in large graphs (e.g., Google’s PageRank in the case of the graph of the World Wide Web) facilitated the construction of excellent web search engines, returning the most important hits corresponding to the submitted user queries. Interestingly, finding important edges – instead of vertices – in large graphs has received much less attention until now. Here we examine the human structural braingraph (or connectome), identified by diffusion magnetic resonance imaging (dMRI) methods, with edges connecting cortical and subcortical gray matter areas and weighted by fiber strengths, measured by the number of the discovered fiber tracts along the edge. We identify several “single” important edges in these braingraphs, whose high or low weights imply the sex or the age of the subject observed. We call these edges implicator edges since solely from their weight, one can infer the sex of the subject with more than 67 % accuracy or their age group with more than 62% accuracy. We argue that these brain connections are the most important ones characterizing the sex or the age of the subjects. Surprisingly, the edges implying the male sex are mostly located in the anterior parts of the brain, while those implying the female sex are mostly in the posterior regions. Additionally, most of the inter-hemispheric implicator edges are male ones, while the intra-hemispheric ones are predominantly female edges. Our pioneering method for finding the sex- or age implicator edges can also be applied for characterizing other biological and medical properties, including neurodegenerative- and psychiatric diseases besides the sex or the age of the subject, if large and high-quality neuroimaging datasets become available. We emphasize that our contribution identifies statistically valid single brain connections related to the sex and the age of the subjects in a large and robust dataset. To our knowledge, our results are unprecedented in this aspect.

Gaussian unitary ensemble in random lozenge tilings

This paper establishes a universality result for scaling limits of uniformly random lozenge tilings of large domains. We prove that whenever the boundary of the domain has three adjacent straight segments inclined under 120 degrees (measured in the direction internal to the domain) to each other, the asymptotics of tilings near the middle segment is described by the GUE–corners process of random matrix theory. An important step in our argument is to show that fluctuations of the height function of random tilings on essentially arbitrary simply-connected domains of diameter N have magnitude smaller than \(N^{1/2}\).

Development of High-Power Bidirectional DC Solid-State Power Controller for Aircraft Applications

The high-power solid-state power controller (SSPC) will be a critical component for the future electrified aircraft propulsion system. This article presents the development of a 1 kV 500 A bidirectional dc SSPC using SiC power modules and transient voltage suppression (TVS) diodes. The design procedure and implementation of the SSPC are presented in detail and the system level influence is discussed. Due to the limited power of a single switch, parallel and/or series connections of switches are necessary for high-power SSPCs, and the corresponding challenges are investigated with possible solutions. In addition, the high peak-to-average clamping voltage ratio caused by Ldi/dt of the turn-off current commutation and foldback characteristics of high-power TVS diodes is addressed. Finally, the testing setups for the high-power SSPC are presented, and all key functions are tested for the SSPC. The power rating and the specific power of the developed SSPC are superior to state-of-the-art counterparts to show the advantage of the developed one.

S3646 Double Pylorus: A Case of Chronic Peptic Ulcer Disease Leading to Formation of a Gastroduodenal Fistula

Introduction: Double pylorus is a rare condition, either congenital or acquired, that results in a gastroduodenal fistula, forming an additional connection between the antrum of the stomach and the duodenal bulb. Case Description/Methods: A 75-year-old female with past medical history of cervical cancer (in remission), hypertension, tobacco use, chronic constipation, and peptic ulcer disease (PUD) presented to the emergency department (ED) with diffuse abdominal pain and blood in her stool. Patient reported intermittent black stools with occasional rectal bleeding. She was using non-steroidal anti-inflammatory drugs (NSAIDs) for headaches. In the ED, patient was hypertensive to 170/75, but other vital signs were stable. Her labs showed a hemoglobin of 12.6 g/dL (normal 12-16 g/dL) without evidence of coagulopathy. Imaging of the abdomen and pelvis did not show any acute findings. Esophagogastroduodenoscopy (EGD) showed two openings to the duodenal bulb, a functional pylorus inferiorly and an accessory channel superiorly (Figure). The two lumens of the duodenum appeared normal without evidence of acute ulceration. Colonoscopy showed a non-bleeding arteriovenous malformation in the proximal ascending colon and internal hemorrhoids, which were likely the cause of her bleeding. Discussion: Acquired double pylorus (ADP) is usually an incidental finding with a prevalence of approximately 0.001-0.4%, affecting males and females in a 2:1 ratio, respectively. Most cases of ADP are secondary to PUD, often an ulcer in the antrum of the stomach or duodenum penetrating directly into the duodenal bulb. Patients can be asymptomatic with ADP, but some may experience vomiting, epigastric pain, or dyspepsia. Melena may also be present with active ulceration. Initial diagnostic approach to ADP should include EGD, assessing NSAID or corticosteroid use, and H. pylori testing. Treatment involves proton-pump inhibitor administration or other mucosal protective agents, avoidance of NSAIDs and steroids, and eradication of H. pylori. Endoscopic division of the tissue bridge with a sphincterome should be considered if severe symptoms of gastric outlet obstruction persist. In severe cases where perforation, refractory bleeding and/or obstruction occurs, a surgical consultation should be pursued. The accessory pathway will typically remain patent for life, but rarely, the channel will close completely or merge to form a single connection to the duodenal bulb.Figure 1.: Double pylorus on EGD. The accessory channel is observed superiorly, revealing a gastroduodenal fistula.

On the effective organization of rural settlements spatial structure under the transformation and development of mountainous areas in Western China: evaluation measurement based on complex adaptability theory.

The vast majority of rural settlements in Western China are located in the ecologically sensitive and diverse mountainous environment, which also experienced rapid changes in policy and institutional interventions over the past 40years. At present, in the transitional period of "post-poverty alleviation," they have more opportunities to re-integrate themselves into the large regional development. However, there is a lack of systematic evaluation and cognition of the related functions of the spatial structure between the settlements at the regional village scale and town scale. Therefore, in this paper, the theory of complex adaptive system and its analytical NK model were introduced, and a quantitative measurement framework was constructed for the adaptability level of this kind of rural settlement spatial structure organization so as to explore the effective path for its global optimization. Taking Xinglong Town of Chongqing in the western mountainous area as an example, it was found from the analysis that (1) the number of villages at a high comprehensive adaptation level has increased over time, which has an obvious positive correlation with the construction of transportation network, and a structural adsorption effect. (2) The spatial structure of the rural settlement system in the region has changed from weak industrial nodes - traffic single branch connection - public service decentralized coverage in 2010 to the organizational adaptation characteristics of stable industrial agglomeration - traffic expansion and extension - public service continuous coverage in 2019. (3) The spatial elements related to industry and public service in each village have an increasingly significant impact on the reconstruction and differentiation of its spatial structure. Finally, based on the changing trend of adaptability level and the correlation characteristics of regional space, in this paper, the spatial structure optimization strategy of Xinglong Town is put forward, which provides a reference basis for the coordinated development of the town and village space under the township-level planning in the western region.

Numerical modeling on shear performance of braced cold-formed steel composite walls

In this paper, the specific influence of diagonal braces on the hysteretic behaviors, including lateral stiffness, yield load, and load-bearing capacity, of braced composite cold-formed steel (CFS) walls have been investigated through the combination of previous experiment results and numerical analysis. A detailed modeling method using connector function in ABAQUS for simulating single screw connection has been introduced. Furthermore, the finite element models based on experimental specimens have been constructed, an excellent match of finite element analysis and experimental results are yielded to prepare for parametric analysis; five significant parameters, vertical load, panel splice type, screw spacing, section thickness of end studs, and diagonal braces, were considered in parametric analysis to in-depth investigate the hysteretic behavior of walls. Finally, some valued conclusions expected to be benefited engineering applications have been summarized.

DSM-MoC as Baseline: Reliability Assurance via Redundant Cellular Connectivity in Connected Cars

Connected Cars (CCs) and vehicle-to-everything (V2X) use cases require stringent reliability for safety and non-safety uses. With increasing network softwarisation, it has become easier to use multiple, redundant connectivity options instead of relying on a single network connectivity. But where should these redundant connections be managed? Is it at a network provider’s core network - i.e., supply side managed (SSM) - or at the CC - i.e., demand side managed (DSM)? In our work, we investigate the use of SSM and DSM for CCs on four separate days and across 800 kilometers of major / minor roads in South East England. For Day 1, we captured performance indicators, and determined hypothetical multi-operator configurations for four U.K. providers and a global Universal SIM. For Day 2, 3 & 4, we built and deployed a test-bed to actually implement network switching and understand performance (incl. for TCP & UDP) either on the road or in a stationary location. Based on our results, we make three contributions. First, we show that DSM can deliver superior performance for CCs more than any individual network (up to 28 percentage points in a hypothetical scenario), or SSM which had up to 4.8x longer page load times. Second, unlike other smartphone-only studies, our system-level study demonstrates that improvements of at least 12% can be obtained in a practical DSM field implementation for a CC. Third, we confirm that the advantage of DSM in a field implementation is higher for UDP traffic (23% better latency) compared to TCP (13%).

Software-Defined Heterogeneous Quantum Key Distribution Chaining: An Enabler for Multi-Protocol Quantum Networks

Quantum key distribution (QKD) is an essential branch of quantum communications that facilitates future-proof security. In the near future, large-scale quantum networks will inevitably encounter diverse QKD protocols, ultimately resulting in a multi-protocol quantum network. Motivated by the evolution of advanced QKD protocols, this article introduces a pivotal enabler for multi-protocol quantum networks: software-defined heterogeneous QKD chaining (HQKDC). In contrast to the conventional QKD chain using a single protocol and a single connectivity pattern, a heterogeneous QKD chain is established relying on multiple protocols and diverse connectivity patterns. We elaborate the HQKDC framework by describing the structures of various QKD chains and proposing an architecture of software-defined HQKDC over optical networks. The software defined networking paradigm and optical networks can facilitate the orchestration and deployment of heterogeneous QKD chains, respectively. Furthermore, we present and evaluate the strategies for heterogeneous QKD chain deployment, as well as devise and demonstrate the workflow for heterogeneous QKD chain orchestration. Finally, we discuss open issues toward the practical QKD network and quantum Internet.

Statistical correlation investigation of a single-doweled timber-to-timber joint

Dowel-type joints are widely used in timber structures given their ease of construction, strength, and capacity to deform before failure. The embedment strength of timber and the bending moment capacity of dowels are considered key properties in the design. On the other hand, these properties have an inherent variability that increases the uncertainties related to the connection’s strength and associated failure modes. This study proposes to quantify the uncertainty related to the statistical correlation behavior between the timber embedment strength and dowel bending moment capacity while comparing analytical solutions to the results of double shear single doweled timber joints. Traditional distribution fitting procedures, as well as copula functions, are implemented to capture their marginal and dependence behavior. Since their source of mutual correlation is known, the effectiveness of the different approaches in describing the statistical dependence structure can be assessed. This is done by investigating how equivalent are the descriptions of dependence by copula functions and directly from the correlation origin. Results obtained here indicate that, for single dowel-type connections in double shear, the impact of the copulas on the results is small, which means that improving their joint characterization represents a minor improvement in the reliability results. Besides the minor differences, the results show that copula functions are a viable tool capable of capturing the nuances of the joint behavior between random variables.

Impact of Time Resolution on Curtailment Losses in Hybrid Wind-Solar PV Plants

Curtailment losses for large-scale hybrid wind–solar photovoltaic (PV) plants with a single grid connection point are often calculated in 1 h time resolution, underestimating the actual curtailment losses due to the flattening of power peaks occurring in shorter time frames. This paper analyses the curtailment losses in hybrid wind–PV plants by utilising different time resolutions of wind and PV production while varying the grid cut-off power, wind/solar PV farm sizes, and shares of wind/PV capacity. Highly resolved 1 s measurements from the operational wind farm and pyranometer are used as an input to specialized wind and PV farm power production models that consider the smoothing effect. The results show that 15 min resolution is preferred over 1 h resolution for large-scale hybrid wind–PV plants if more accurate assessment of curtailment losses is required. Although 1 min resolution additionally increases the estimation accuracy over 15 min resolution, the improvement is not significant for wind and PV plants with capacity above approx. 10 MW/10 MWp. The resolutions shorter than 1 min do not additionally increase the estimation accuracy for large-scale wind and PV plants. More attention is required when estimating curtailment losses in wind/PV plants with capacity below approx. 10 MW/10 MWp, where higher underestimation can be expected if lower time resolutions are used.

Flexural Performance of Splice Connections in Cross-Laminated Timber

This study demonstrates the moment resistance performance of various splice connections of cross-laminated timber (CLT) subjected to flatwise bending. A total of 33 samples in two groups (half-lapped and single-splined) were tested under four-point bending. The influence of fastener types on the half-lapped connections was investigated. Additionally, different lap lengths were considered to understand the influence of lap length on different fastener types. Steel plates with two different thicknesses and plywoods were attached with bolts onto the bottom face only to make the single spline connections. Additionally, plywoods were attached to the CLT members in two ways: (i) with the bolt only and (ii) glue plus bolts. The effect of bolt diameters on the spline connections was also examined, and the connections were tested along both the major and minor axes. To determine the characteristic values of the resistance properties, a statistical analysis was carried out following EN 14358:2016. The results indicate the bolted lap connections experience plastic deformations, whereas the screwed lap connections exhibit relatively linear behaviour until failure. The bolted and screwed lap connection with a lap length of 100 mm showed 39% and 33% higher moment capacity, respectively, than that with a 75 mm lap length. Additionally, the rotational rigidity and ductility of the lap connections increase with the increase in lap length. Irrespective of lap lengths, the bolted lap connections show higher moment capacity, support rotation and ductility, but lower rotational rigidity than screwed lap connections. An increase in bolt diameter increases moment capacity but decreases rotational rigidity. Compared to the plywood spline connections, the steel spline connections showed approximately 24%, 5% and 73% higher moment capacity, rotational rigidity and ductility, respectively. Additionally, the plywood spline connections without glue performed better than glued connections. Overall, compared to the half-lapped connections, the single-spline connections showed better performance.

Single Connection Amid Vertices From Two Given Sets Partitioning Vertex Set in Some Classes of Neutrosophic Graphs

Single Connection Amid Vertices From Two Given Sets Partitioning Vertex Set in Some Classes of Neutrosophic Graphs

Experimental performance of single blind-bolted CFST column connection under predominant shear loading

This paper presents experimental findings of ten full-scale blind-bolted concrete-filled steel tubular (CFST) connection tests under predominant shear loading. Previous works show that, the performance of blind-bolts with extended shank and headed nut performed significantly well under tensile loads, but research on such connections under shear loading is at scarce. In this testing programme, the performance of individual blind-bolted CFST column connection is assessed where various parameters including presence of infill concrete, bolt embedment length, tube wall thickness and concrete strength are considered. Material tests for all the elements in the connection assembly have also been conducted. The study is accompanied by assessment of international codes. It is observed that, with higher bolt embedment length, the concrete contribution can be enhanced up to 58% of the total load applied, where the load is transmitted to the concrete core by bearing, and the tube wall yielding could also be delayed. Test results also shows that, ultimate capacity of the bolts can be achieved with CFST connections under shear load. For all the connections, the failure mode was consistent to shear fracture of bolt. At the end, a modified prediction equation for blind-bolt shear resistance is proposed. The test results presented in the investigation provides scientific data for further numerical investigations and can also provide insights towards load-introduction mechanism in bolted CFST column connections.

Energy minimizing twinning with variable volume fraction, for two nonlinear elastic phases with a single rank-one connection

In materials that undergo martensitic phase transformation, distinct elastic phases often form layered microstructures — a phenomenon known as twinning. In some settings the volume fractions of the phases vary macroscopically; this has been seen, in particular, in experiments involving the bending of a bar. We study a two-dimensional (2D) model problem of this type, involving two geometrically nonlinear phases with a single rank-one connection. We adopt a variational perspective, focusing on the minimization of elastic plus surface energy. To get started, we show that twinning with variable volume fraction must occur when bending is imposed by a Dirichlet-type boundary condition. We then turn to paper’s main goal, which is to determine how the minimum energy scales with respect to the surface energy density and the transformation strain. Our analysis combines ansatz-based upper bounds with ansatz-free lower bounds. For the upper bounds we consider two very different candidates for the microstructure: one that involves self-similar refinement of its length scale near the boundary, and another based on piecewise-linear approximation with a single length scale. Our lower bounds adapt methods previously introduced by Chan and Conti to address a problem involving twinning with constant volume fraction. The energy minimization problem considered in this paper is not intended to model twinning with variable volume fraction involving two martensite variants; rather, it provides a convenient starting point for the development of a mathematical toolkit for the study of twinning with variable volume fraction.