Plane Separation Research Articles

Ductile-brittle transition at edge cracks (001)[110] in BCC iron under different loading rates in mode I: a 3D atomistic study

3D atomistic simulations via molecular dynamics (MD) at temperature of 0 K and 295 K (22 °C) with a high quasi-static loading rate dP/dt of 2.92 kN s−1 show that cleavage fracture is supported by surface emission of oblique dislocations and by their subsequent cross slip to {112} planes, which increases separation of the (001) cleavage planes inside the crystal. Under the slower loading rate by a factor 5, the crack growth is hindered by twin generation on oblique planes {112} and the fracture is ductile. The MD results explain the contribution of the crack itself to the ductile-brittle transition observed in our fracture experiments on Fe-3wt%Si single crystals of the same orientation and geometry, loaded at the same rates dP/dt as in MD. The loading rates are equivalent to the cross head speed of 5 mm min−1 and 1 mm min−1 used in the experiment. The MD results also agree with the stress analysis performed by the anisotropic LFM and comply with experimental observations.

Magnetic transition in the [formula omitted] Kagomé system Sm[formula omitted]Sb[formula omitted]Zn[formula omitted]O14

We present a study of Sm3Sb3Zn2O14 (SSZO) through magnetization and specific heat capacity Cp(T) measurements. SSZO contains well separated planes of Sm3+ magnetic ions on a Kagomé lattice. Though our magnetic susceptibility (where the data are limited down to 2K) does not show any anomaly, the Cp(T) data which have been taken down to 0.35 K reveal a broad maximum at T∼1.5K followed by a sharp peak at T∼0.5K indicative of short-range correlations and long-range order, respectively.

Role of layer thickness and dislocation distribution in confined layer slip in nanolaminated Nb

Confined layer slip (CLS) is considered as the primary mechanism for plastic deformation in nanolaminates. It depicts the confined motion of a single dislocation between two parallel interfaces nanometers apart. Using atomistic simulations, we investigate the effects of interface spacing, or equivalently individual layer thickness, and dislocation distribution on the CLS of an edge dislocation in nanolaminated Nb with coherent twin boundaries and Nb nanofilm. We show that CLS motion transitions from smooth glide to staggered glide as the nanolayer thickness increases, while the line bows out, as theoretically pictured. For the same nanolayer thicknesses L, dislocation CLS in the nanofilm is smooth and the CLS resistance is 47% to 79% lower. For both the nanolaminate and film, the nanolayer size L effect on CLS resistance is found to follow the expected ln(L)/L scaling with an additional constant that depends on the interface/dislocation interaction but is independent of L. When like-signed dislocation glide concurrently on the same glide plane in the adjacent layers, the dislocations move with almost no bow-out, and the CLS resistance is substantially reduced, even below that of the thin film bounded by two free surfaces. With an increase in the glide plane separation between like-signed dislocations in the neighboring layers, a higher flow stress is obtained. However, when the dislocations are oppositely signed, CLS motion is jerky and the stress fluctuates and overall increases three fold.

Applying Federated Learning in Software-Defined Networks: A Survey

Federated learning (FL) is a type of distributed machine learning approacs that trains global models through the collaboration of participants. It protects data privacy as participants only contribute local models instead of sharing private local data. However, the performance of FL highly relies on the number of participants and their contributions. When applying FL over conventional computer networks, attracting more participants, encouraging participants to contribute more local resources, and enabling efficient and effective collaboration among participants become very challenging. As software-defined networks (SDNs) enable open and flexible networking architecture with separate control and data planes, SDNs provide standardized protocols and specifications to enable fine-grained collaborations among devices. Applying FL approaches over SDNs can take use such advantages to address challenges. A SDN control plane can have multiple controllers organized in layers; the controllers in the lower layer can be placed in the network edge to deal with the asymmetries in the attached switches and hosts, and the controller in the upper layer can supervise the whole network centrally and globally. Applying FL in SDNs with a layered-distributed control plane may be able to protect the data privacy of each participant while improving collaboration among participants to produce higher-quality models over asymmetric networks. Accordingly, this paper aims to make a comprehensive survey on the related mechanisms and solutions that enable FL in SDNs. It highlights three major challenges, an incentive mechanism, privacy and security, and model aggregation, which affect the quality and quantity of participants, the security and privacy in model transferring, and the performance of the global model, respectively. The state of the art in mechanisms and solutions that can be applied to address such challenges in the current literature are categorized based on the challenges they face, followed by suggestions of future research directions. To the best of our knowledge, this work is the first effort in surveying the state of the art in combining FL with SDNs.

An efficient virtual machine allocation using single stage weapon target assignment model in cloud software‐defined network environment

SummaryWith the rapid growth of the Internet, technological advancements, and the increasing number of cloud users, a paradigm transformation towards separate data and control planes with a centralized control point is taking place. As a result of this separation, software‐defined networks (SDNs) have distinct software controllers for routers and the capacity to manage network behavior. Virtual machine placement (VMP) and virtual machine migration (VMM) are two examples of SDN usage in data centers. The issue of VMP in cloud environments is a significant challenge that has been widely researched but not fully resolved. In this research, we used the single stage weapon target assignment (SSWTA) to model the virtual machine allocation (VMA) for jobs in order to maximize the resource utilization of the physical machines (PMs) by reducing idle time. Furthermore, this research proposes three algorithms: job assignment algorithms, PM allocation (PMA) using the least recently used (LRU) policy, and optimal VMA. The proposed VMA's performance is compared to other related VMA models such as first fit decreasing, and it is determined to be efficient in terms of resource utilization.

Transparent 2-Element 5G MIMO Antenna for Sub-6 GHz Applications

A dual-port transparent multiple-input multiple-output (MIMO) antenna resonating at sub-6 GHz 5G band is proposed by using patch/ground material as transparent conductive oxide (AgHT-8) and a transparent Plexiglas substrate. Two identical circular-shaped radiating elements fed by using a microstrip feedline are designed using the finite element method (FEM) based high-frequency structure simulator (HFSS) software. The effect of the isolation mechanism is discussed using two cases. In case 1, the two horizontally positioned elements are oriented in a similar direction with a separate ground plane, whereas in case 2, the elements are vertically placed facing opposite to each other with an allied ground. In both cases, the transparent antennas span over a −10 dB band of 4.65 to 4.97 GHz (300 MHz) with isolation greater than 15 dB among two elements. The diversity parameters are also analyzed for both the cases covering the correlation coefficient (ECC), mean effective gain (MEG), diversity gain (DG), and channel capacity loss (CCL). The average gain and efficiency above 1 dBi and 45%, respectively with satisfactory MIMO diversity performance, makes the transparent MIMO antenna an appropriate choice for smart IoT devices working in the sub-6 GHz 5G band by mitigating the co-site location and visual clutter issues.

Plane-separated routing in ad-hoc networks

Control and user (data) plane separation (CUPS) is a concept applied in various networking areas to scale network resources independently, increase the quality of service, and facilitate the autonomy of networks. In this study, we leverage this concept to design a plane-separated routing algorithm, CUPS-based hierarchical routing algorithm (CHRA), as an energy-efficient and low-latency end-to-end communication scheme for clustered ad-hoc networks. In CHRA, while cluster heads constitute the control plane to conduct network discovery and routing, ordinary nodes residing in the user plane forward packets according to the routing decisions taken by the control plane. Exploiting the CUPS, we avoid exhausting cluster heads by offloading packet-forwarding to ordinary nodes and improve the quality of service by utilizing alternative paths other than the backbone of cluster heads. Our simulation results show that CHRA offers a better quality of service in terms of end-to-end latency and data-to-all ratio, and promotes fairness in energy-consumption in both stationary and mobile scenarios.

Topology Optimization under Both-sided Casting Constraint without Specifying the Separation Plane

Topology Optimization under Both-sided Casting Constraint without Specifying the Separation Plane

SDN-Based Traffic Matrix Estimation in Data Center Networks through Large Size Flow Identification

Software defined networking (SDN) with separated control plane and data plane brings new opportunities for traffic measurement in data center networks. However, in the SDN-enabled switches, available TCAM (Ternary Content Addressable Memory) resources for traffic measurement are limited. Thus, it is necessary to utilize traffic matrix (TM) estimation to derive a hybrid network monitoring scheme through combining the partial direct measurement offered by SDN with some inference techniques. Although large size flows play an important role in improving TM estimation accuracy, directly monitoring each flow and finding out large size flows consume massive channel bandwidth resource between control plane and data plane. Therefore, in this paper, we identify large size flows from multiple historical TMs instead of monitoring each flow. First, we analyze multiple historical TMs and observe that origin-to-destination (OD) pair whose flow size is selected as large size flow at last time slot is most likely to be selected for per-flow monitoring at next time slot, so these OD pairs are identified by gradient boosting machine and are directly regarded as sampled OD pairs in order to reduce resource consumption. Then, we propose a greedy heuristic algorithm to solve SDN-enabled switch selection problem to best utilize the TCAM resources and guarantee that most of sampled OD pairs are measured in the flow table. We also present a source node prefix tree based bit merging aggregation (SPTBMA) scheme to design feasible forwarding rules to be inserted in TCAM of SDN-enabled switches and reserve more TCAM space for sampled OD pairs. Finally, the experimental results based on real traffic dataset demonstrate that our proposed scheme outperforms the existing algorithms in terms of improving TM estimation accuracy and overcoming limitation of TCAM resources.

Verb Movement and Pair-Merge

Government and Binding posited that the head operation in question involves adjunction of a lower head to a higher head in narrow syntax. It has been noted early, however, that this approach is highly problematic because head-adjunction violates several well-motivated constraints like proper binding condition, extension condition, chain uniformity condition and A- over-A principle. Thus Chomsky(2015) redefines head movement under pair- merge of heads, which can not be seen in syntax due to the fact that head is thought to be attached to the moved head on a separate plane. However in this article this internal pair -merge of heads(head adjunction) seems to be no longer available because it potentially produces multi-dominance and violation of some desiderata (Chomsky 2019) like RCR, DA, Strict Binary and also anaysis of bridge verb construction as well. Thus this proposal proposes that MERGE can redefine internal pair-head merge like R-to-v movement under feature sharing with an identical feature, which renders two-membered pair-merge into one-membered MERGE(amalgam). This operation with feature sharing ensures the basic derivation in Chomsky (2019)’s 7 desiderata as well as multi-dominance, extention condition and A-over-A principle.

DEVELOPMENT OF DIES WITH DIFFERENTIATED CLAMP FOR CUTTING BLANKS FOR PRECISION STAMPING

A large contribution to the final cost of machine-building products is made by the efficiency of blank production, in which a waste-free shear cut is used. The most promising for the implementation of the method of shear cutting are dies with a differentiated clamping of rolled products. The aim of the work is to develop a new die design with a differentiated clamping of rolled products with high technical and economic characteristics and recommendations for the design of such equipment. On the basis of the developed graph of constructions of dies with a differentiated clamping of rolled products, design features have been identified, which made it possible to create a new die design. Compared with the known structures, in the stamp of the DSEA structure, the transverse dimensions and weight are reduced by an average of 25%, and the height of the open stamped space – by 10%. In the process of dividing in the vertical plane, a constant position of the rolling axis is ensured. The transfer of force to the clamp through the rolling is excluded. The stamp has high rigidity. The stamps of the DSEA design have been introduced at the Odessa PJSC "Stroygidravlika". The economic effect of the implementation was 100000 UAH. Acceptance test results showed that the dies of the new design are efficient and reliable in operation. The quality of the cut workpieces corresponds to the quality indicators of the workpieces cut on modern similar equipment. On the basis of theoretical analysis, experimental studies and operating experience of dies with differential clamping of rolled products, known and formulated new recommendations for the design of such dies. The main ones are: it is necessary to provide a differentiated clamping of rolled products on both sides of the separation plane, subject to the condition that the clamping force should be one and a half times greater than the cutting force; the die body is preferably box-shaped to compensate for thrust forces and torsional moments of forces; the power parts of the stamp must be made in a closed form with stiffening ribs to ensure strength under cyclic stress conditions.

Simulation analysis of a method to improve data-transmission performance of Nanshan 26m Radio Telescope based on Software-Defined Networks

Data Center of Xinjiang Astronomical Observatory (XAO-DC) commenced operating in 2015, and provides services including archiving, releasing and retrieving precious astronomical data collected by the Nanshan 26m Radio Telescope (NSRT) over the years, and realises the open sharing of astronomical observation data. The observation data from NSRT are transmitted to XAO-DC 100 km away through dedicated fiber for long-term storage. With the continuous increase of data, the static architecture of the current network cannot meet NSRT data-transmission requirements due to limited network bandwidth. To get high-speed data-transmission using the existing static network architecture, a method for reconstruction data-transmission network using Software-Defined Networks (SDN) is proposed. Benefit from the SDNʼs data and control plane separation, and open programmable, combined with the Mininet simulation platform for experiments, the TCP throughput (of single thread) was improved by ∼24.7%, the TCP throughput (of multi threads) was improved by ∼9.8%, ∼40.9%, ∼35.5% and ∼11.7%. Compared with the current network architecture, the Latency was reduced by ∼63.2%.

The Benefits of 3D and 4D Synthesis of Marine Geophysical Datasets for Analysis and Visualisation of Shipwrecks, and for Interpretation of Physical Processes over Shipwreck Sites: A Case Study off Methoni, Greece

Through the study of three wreck sites over the Methoni Bay (Greece), this article presents the benefits of spatio-temporal integration and correlation of marine geophysical data in a common three-dimensional (3D) geographical platform for analysis, and visualisation of shipwreck ruins and for interpretation of physical processes over wreck sites. The integration of 3D datasets has been proven to support identification of archaeological features over and under the seafloor, evaluation of the wreck structure state, and assessment on the wrecking event and the wreck site arrangement at that time, due to interactive cross-examination of datasets acquired in separate planes. Data synthesis is fundamental for 3D digital reconstruction of scattered and partially buried shipwreck ruins in complex geology as every dataset acts as interpretive and complimentary to each other. It is also shown that data synthesis highlights the signatures of physical processes over the wreck sites, and the interaction between the processes and the shipwrecks. The analysis of spatio-temporal, four-dimensional (4D) integrated datasets has proved to provide knowledge on the wreck site evolution through time, and highlights the disturbance of underwater archaeological resources due to human activities. The study has also shown that the creation of a shoalest depth true position bathymetric surface supports the realistic 3D wreck representation over the seafloor.

Pilot plant tests to demonstrate the functionality of sealing elements made of salt cut bricks

Abstract. The long-term safe containment of high-level radioactive waste in a repository in rock salt is ensured if the geological barriers in conjunction with the geotechnical barriers are permanently impermeable to fluids. As such, an essential factor in underground disposal is to confirm that the interfaces between the biosphere and the lithosphere, i.e., shafts, boreholes, and galleries, created during the excavation of underground cavities can be sufficiently tightly sealed. An essential element of the sealing system required to this end is shaft closure. All shaft closure concepts developed thus far include sealing and supporting elements in repository shafts, but differ in the arrangement of these structural elements and the materials used. The materials currently proposed and planned for the construction of the sealing elements include: clay/bentonite, asphalt/bitumen, crushed salt, and salt/sorel cement. In addition to the materials mentioned above, a research project funded by the German Federal Ministry for Economic Affairs and Energy (Bundesministerium für Wirtschaft und Energie, BMWi) is investigating the possibility of integrating a layer of salt cut bricks several decameters to 100 m thick into the shaft closure system as a sealing element that provides the option of allowing the geological barrier to heal in the long term. Like the surrounding rock mass, the salt cut bricks are made of natural rock salt. According to this plan, the profile of the bricks is designed to minimize joint volume as far as possible by cutting them to match the geometry of the shaft. The joints between the salt cut bricks can either be filled with, for example, a supersaturated salt solution, Magnesium building materials, molten salt, crushed salt, etc., or directly brought into contact by wetting the surface of the salt cut bricks. Once the salt solution has hardened (cooling of the solution, evaporation of the mixing water), only the pore space in the crushed-salt joint sealant filled with salt solution or air, or the joint volume resulting from the mismatch between individual rock salt bricks are susceptible to a reaction. This means that the sealing element consisting of salt cut bricks develops early supporting pressure against the creeping rock salt of the rock mass compared to crushed salt, has a low initial porosity and already shows a strong sealing effect in the short term (regression of the loosened zone). One can also assume that cohesive bonding between the surrounding rock and the sealing element can already be achieved by introducing the joint filling or by wetting the contact surfaces of the salt cut bricks (no or reduced separation planes in the contact zone). Essential prerequisites for the investigation of the geomechanical-geohydraulic effectiveness of a sealing element made of salt cut bricks included the development and construction of a pilot plant to analyze the mechanical and hydraulic material properties of the bonding system comprising salt cut bricks and joint sealing (FKZ 02E11223, FKZ 02E11425), as well as preliminary investigations on the production of salt cut bricks and joint sealant (→ cutting technique/processing of salt cut bricks; maufacture/workability of jointing material) and on the spatial arrangement of the salt cut bricks (→ avoidance of continuous axial joints in the bonding system, Fig. 1). The presentation includes the results of the research work on the development, construction and commissioning of the pilot plant, as well as the first successful test results demonstrating the functionality of sealing elements made of salt cut bricks.

A completely automated pipeline for 3D reconstruction of human heart from 2D cine magnetic resonance slices.

Cardiac magnetic resonance (CMR) imaging is a valuable modality in the diagnosis and characterization of cardiovascular diseases, since it can identify abnormalities in structure and function of the myocardium non-invasively and without the need for ionizing radiation. However, in clinical practice, it is commonly acquired as a collection of separated and independent 2D image planes, which limits its accuracy in 3D analysis. This paper presents a completely automated pipeline for generating patient-specific 3D biventricular heart models from cine magnetic resonance (MR) slices. Our pipeline automatically selects the relevant cine MR images, segments them using a deep learning-based method to extract the heart contours, and aligns the contours in 3D space correcting possible misalignments due to breathing or subject motion first using the intensity and contours information from the cine data and next with the help of a statistical shape model. Finally, the sparse 3D representation of the contours is used to generate a smooth 3D biventricular mesh. The computational pipeline is applied and evaluated in a CMR dataset of 20 healthy subjects. Our results show an average reduction of misalignment artefacts from 1.82 ± 1.60 mm to 0.72 ± 0.73 mm over 20 subjects, in terms of distance from the final reconstructed mesh. The high-resolution 3D biventricular meshes obtained with our computational pipeline are used for simulations of electrical activation patterns, showing agreement with non-invasive electrocardiographic imaging. The automatic methodologies presented here for patient-specific MR imaging-based 3D biventricular representations contribute to the efficient realization of precision medicine, enabling the enhanced interpretability of clinical data, the digital twin vision through patient-specific image-based modelling and simulation, and augmented reality applications.This article is part of the theme issue ‘Advanced computation in cardiovascular physiology: new challenges and opportunities’.

Terahertz digital holography: Two- and four-step phase shifting technique in two plane image recording

A two- and four-step phase shifting (PS) technique in terahertz (THz) digital holography is proposed. Relying on the Mach–Zehnder interferometer-based setup, it was demonstrated that the two-step and four-step PS in Fresnel holograms can assist in a five times greater background subtraction. It allows us to improve the quality of the obtained holographic images, in particular when objects introduce phase changes. It was shown that the recording of holograms of an object consisting of two separated planes can enable qualitative reconstruction of 3D images. Here, the planes were separated by 30 mm, thus defining the longitudinal (depth) resolution in this experiment. It is shown that the PS can serve in distinguishing transparent objects and, by a proper selection of phase variation within the 0–2π range, enable us to increase the quality of the reconstructed hologram. Finally, the advantages of the suggested holographic technique are illustrated by comparing the results with the data of weak absorbing objects obtained via point-to-point, plane-to-plane (4f setup), and dark-field THz imaging approaches. Experiments were performed at frequencies of 0.3 and 0.6 THz recording THz images using resonance antenna-coupled titanium microbolometers.

Use of data-driven design for the development of knob-shaped handles in the context of impedance measurements

It can be inferred from hand-arm impedance analyses that the grip forces of users have a great influence on the transmitted vibrations. To determine this influence on test benches, the state of research suggests a cylindrical measuring handle. Since this shape is not suitable for all power tool handles, we develop a design for a knob-shaped measuring handle. The grip force applied to an orbital sander was measured in a test person study. The recorded data was combined with a 3D scan and evaluated by an algorithm which determined the separation plane of the measuring handle to integrate the force sensors. This plane is perpendicular to the vector of the subjects’ grip forces. Furthermore, it divides the knob-shaped handle of the sander primarily vertically. The determination of the separation plane enables the design of a knob-shaped measuring handle for grip force measurement to analyze the hand-arm impedance of an overlying hand position.

Recurrent brainstem cavernous malformations following primary resection: blind spots, fine lines, and the right-angle method.

Proximity of brainstem cavernous malformations (BSCMs) to tracts and cranial nerve nuclei make it costly to transgress normal tissue in accessing the lesion or disrupting normal tissue adjacent to the lesion in the separation plane. This interplay between tissue sensitivity and extreme eloquence makes it difficult to avoid leaving a remnant on occasion. Recurrences require operative intervention, which may increase morbidity, lengthen recovery, and add to overall costs. An approximately 20-year experience with patients with recurrent BSCM lesions following primary microsurgical resection was reviewed. A prospectively maintained database of 802 patients who underwent microsurgical resection of cerebral cavernous malformations during 1997-2018 was queried to identify 213 patients with BSCMs. A retrospective chart review was conducted for patients with recurrent BSCM after primary resection who required a second surgery. Fourteen of 213 patients (6.6%) underwent repeat resection for recurrent BSCM. Thirty-four hemorrhagic events were observed among these 14 patients over 576 patient-years (recurrent hemorrhage rate, 5.9% per year; median discrete hemorrhagic events, 2; median time to rehemorrhage, 897 days). BSCM occurred in the pons in 10 cases, midbrain in 2 cases, and medulla in 2 cases. A blind spot in the operative corridor was the most common cause of residual BSCM (9 patients). All recurrent BSCMs were removed completely, although 2 patients each required 2 operations to treat recurrence. Twelve patients had unchanged or improved modified Rankin Scale scores at last clinical evaluation compared with admission, and 2 patients had worse scores. Recurrence was more common among patients who were operated on in the first versus the second half of the series (8.5% vs 4.7%). The 6.6% rate of BSCM recurrence requiring reoperation reflects the fine lines between complete resection and recurrence and between safe and harmful surgery. The detection of remnants is difficult postoperatively and remains so even at 6 months when the resection bed has healed. The 5.9% annual hemorrhage risk associated with recurrent BSCM in this experience is consistent with that reported for unoperated BSCMs. The right-angle method helps to anticipate blind spots and meticulously inspect the resection cavity for residual BSCM during surgery. A low percentage of recurrent BSCM (5%-10%) ensures ongoing effort toward an acceptable balance of safety and completeness.

Optimization of open flow controller placement in software defined networks

The world is entering into the era of Big Data where computer networks are an essential part. However, the current network architecture is not very convenient to configure such leap. Software defined network (SDN) is a new network architecture which argues the separation of control and data planes of the network devices by centralizing the former in high level, centralised devices and efficient supervisors, called controllers. This paper proposes a mathematical model that helps optimizing the locations of the controllers within the network while minimizing the overall cost under realistic constrains. Our method includes finding the minimum cost of placing the controllers; these costs are the network latency, controller processing power and link bandwidth. Different types of network topologies have been adopted to consider the data profile of the controllers, links of controllers and locations of switches. The results showed that as the size of input data increased, the time to find the optimal solution also increased in a non-polynomial time. In addition, the cost of solution is increased linearly with the input size. Furthermore, when increasing allocating possible locations of the controllers, for the same number of switches, the cost was found to be less.

Universal optical network architecture for future wireless LANs [Invited

Ultra-high-capacity indoor wireless connectivity is considered a key technology enabler to support end-to-end delivery of new services in the beyond-5G and 6G era. With physical layer data rates well beyond 10 Gbps, optical wireless communication (OWC) technology is positioning itself as a prospective candidate to support these services. While OWC is capable of handling multi-gigabit data rates in the wireless domain, the underlying distribution network architecture is not designed to transport the projected high volumes of data as well as the expected added complexity of managing and coordinating multiple narrow beams, beamsteering, and femto cells. To future proof wireless local area networks (LANs) including those using the radio spectrum, we propose a universal network architecture that features centralized software/hardware resource pools as well as control and data plane separation in conjunction with virtualization support and a high-capacity fiber distribution network. Such an architecture has the potential to realize interoperability between existing and future high-capacity wireless LAN technologies such as Wi-Fi 6 and Wi-Fi in the 60 GHz range, as well as dynamic and flexible allocation of resources in response to changing user bandwidth demand. Our results demonstrate the benefits of the universal network architecture in supporting high throughput performance, low delay, and increased resiliency.