Loop Connections Research Articles

Economic power control for offshore wind farms with loop connection cables

Abstract The Canadian developer and owner of green power facilities Northland Power Inc. owns two offshore wind farms (OWFs) in the German Bight, Deutsche Bucht and Nordsee One, operated by the subsidiary Northland Power Europe GmbH. The company supports and conducts research in the field of power flow optimization in wind farm networks. The work at hand represents the results of this effort to maximize the efficiency of the assets. The project was accomplished within a cooperation between the Nordsee One GmbH and the Institute of Electrical Power and Energy Technology at the Hamburg University of Technology. From an external point of view, an OWF represents an “en bloc” power plant connected to the onshore transmission grid via power export cables. Nevertheless, such a power plant comprises a complex, large-scale internal medium voltage network. In case of failure or cable outage, the network topology of an OWF may be modified and unintended overloading of inter-array cables (IACs) is possible. In order to address this issue, a new algorithm and software tool for economic power control in OWFs are introduced in the following which can be employed in wind farms with integrated loop connection cables (LCCs). This configuration particularly entails the risk of overloading cable segments depending on the present wind speed. The new algorithm provides the operator with adapted active power setpoints for each wind turbine generator (WTG) in a given network topology. The aim is to maximize OWF power generation and minimize internal power losses while secure network operation is guaranteed. Using load flow analysis based on WTG power output measurements, the load on each cable section is monitored and the cables can be utilized to their individual full capacity while overload is avoided. The practicability of the approach is demonstrated by means of simulation results.

Influence of reinforcement arrangement details on mechanical behavior of precast concrete barrier with loop connection

Concrete bridge barriers are installed as road safety facilities to prevent vehicles or pedestrians on the road from exiting the lane or entering the opposing lane. Deterioration due to the aging of reinforced concrete members, vehicle crashes, and renovation/extension of bridges necessitate the repair and reinstallation of barriers. A precast concrete barrier solution is used to replace old deteriorated barriers to enable fast and effective completion of structures. This precast barrier is connected to a highly durable cementitious mortar injected into the loop rebar connection. This research shows that a beam specimen can be utilized to understand the detailed behavior of the connection. The results of the experimental study indicate that the configuration of the loop reinforcement provides excellent anchoring capacity and a failure mode that is more stable and capable of greater energy absorption than the existing system. It is revealed that the cracking pattern and mechanical behavior of the reinforcement are highly influenced by the re-arrangement of the reinforcement in the connection. The reinforcement congestion and stress concentration at the edge can be resolved safely by the details proposed in this study, and it can be used effectively for the design of impact loading conditions. The outcomes of this work will lead to important design guidelines for the connection of precast concrete barriers with deck slabs.

4302 Decreased structural basal ganglia motor loop connections in Vascular Parkinsonism compared to Parkinson’s disease and healthy aging

OBJECTIVES/GOALS: This study uses diffusion kurtosis imaging (DKI) to investigate the structural profiles of basal ganglia (BG) motor circuitry in Vascular Parkinsonism (VP), Parkinson’s disease (PD), and healthy aging controls (HC). VP is a clinical diagnosis of lower body predominant parkinsonism without significant benefit from levodopa. VP is distinct from PD, yet the concept of VP remains debated due to the inability of prior studies to identify specific causative changes. One reason for this may be limitations in measuring intricate BG connectivity in vivo. Given the predominant lower body parkinsonism symptoms in VP, we hypothesized that VP would be associated with decreased connectivity specifically within the BG motor loop. METHODS/STUDY POPULATION: We obtained DKI brain imaging in subjects with VP (N = 7), PD (N = 21), and HCs (N = 58), the latter of which had cardiovascular risk factors but no neurological symptoms. The VP and PD groups were evaluated by a parkinsonism-focused motor exam and brief cognitive testing. We compared BG motor loop connectivity between groups and investigated for correlation between connectivity and clinical scores. To account for differences in fiber counts due to the different imaging scanners and protocols between cohorts, we used a BG motor loop proportion, which was the ratio of the BG motor loop fiber count over a control loop, the visual processing pathway. We used Kruskal-Wallis rank sum test with post-hoc Dunn tests to assess imaging findings between subject groups, and Pearson’s correlation to look for correlation between clinical scores and fiber counts. RESULTS/ANTICIPATED RESULTS: The whole brain connectome showed the fewest number of fibers in VP, followed by PD, and then HC (p<0.0001). The BG motor loop proportion fiber count of the BG motor loop was lower in the VP group, compared to the PD and HC cohorts (p = 0.031). In the VP group, the whole brain connectome fiber count correlated with a gait and balance subscore of the Movement Disorders Society - Unified Parkinson Disease Rating Scale (R = −0.87, p = 0.01). DISCUSSION/SIGNIFICANCE OF IMPACT: This study indicates that VP is associated with decreased structural connectivity, with a disproportionate degree of loss in the BG motor circuitry. While the etiology for this susceptibility to injury and preferential damage to BG remains to be defined, these findings can provide an important starting point for a biological understanding of VP, and a potential future marker for diagnosis and tracking disease progression.

English

English

Wall to Wall Horizontal Connection for Precast Concrete Structures

Precast concrete wall is one of the prefabricated components of high demands in the construction industry especially in residential buildings as it combines the benefit of rapid speed of construction, good quality control and minimum labour intensity at the construction site. Precast wall is produced in forms of wall panels and connected in the construction site to form an integrated structural element called precast concrete wall. However, the connection of wall panels is a key factor as it provides the structure integrity and robustness of the overall structural system. Therefore, this paper aims to describe and summarize types of precast wall-to-wall horizontal connection in terms structural behaviours such as embedded length, bonding stress, seismic behaviours and modes of failure. A total number of ten (10) out of eighteen (18) papers will be reviewed and discussed. The findings show that loop connection is suitable for seismically stabile zones as it is not capable to withstand lateral load action effectively whereas wire rope connection has insufficient ductility as the load-carrying capacity is governed by yielding of the lock bar and crushing of the joint mortar. Furthermore, U-shaped steel channel connection, the connection was developed for seismic zones. Providing U-shaped rubber in between the U-shape steel channel has made the connection more flexible with energy dissipater system.

A Building-Block Approach to State-Space Modeling of DC-DC Converter Systems

Small-signal models of DC-DC converters are often based on a state-space averaging approach, from which both control-oriented and other frequency-domain characteristics, such as input or output impedance, can be derived. Updating these models when extending the converter by filters or non-trivial loads, or adding control loops, can become a tedious task, however. To simplify this potentially error-prone process, a modular modeling approach is being proposed in this article. It consists of small state-space models for certain building blocks of a converter system on the one hand, and standardized operations for connecting these subsystem models to an overall converter system model on the other hand. The resulting state-space system model builds upon a two-port converter description and allows the extraction of control-oriented and impedance characteristics at any modeling stage, be it open loop or closed loop, single converter or series connections of converters. The ease of creating more complex models enabled by the proposed approach is also demonstrated with examples comprising multiple control loops or cascaded converters.

Vortex-induced vibrations of dual-step cylinders with different diameter ratios in laminar flows

Vortex-induced vibrations of dual-step cylinders in laminar flows at the Reynolds number of 200 based on a larger diameter are investigated through three-dimensional direct numerical simulations. Four larger-to-smaller diameter ratios (D/d) of 4.0, 2.0, 1.43, and 1.19 are considered for the cylinder with a low mass ratio of 2. Numerical results reveal that D/d significantly influences vibration responses and the vortex shedding process. The case with D/d = 1.43 can effectively reduce vibration amplitudes. The wake vortices are shed in cellular patterns along the cylinder span, with a distinct frequency for each cell. A direct and “X-shaped” connection of wake vortex-shedding modes occurs between different vortex cells, and a loop connection appears between the same cell vortices. A new wake pattern entitled the “out-of-phase vortex shedding” is found downstream of the smaller cylinder at D/d = 2.0. This is manifested by the wake vortices not being shed at a fixed frequency and intensity. The essential reason for this phenomenon lies in a non-lock-in condition between the structural vibration and vortex shedding frequencies of the smaller cylinder. As D/d decreases, a coherence between vortex cells is enhanced, leading to a disappearance of the “out-of-phase vortex shedding.”

Performance of Loop Connection in Precast Concrete Walls Subjected to Lateral Loads

Industrialized building system (IBS) was presented to complete construction projects at the lowest cost and time. The connection of precast components in IBS structures plays a significant role to provide stability of buildings subjected to various loads. Hence, structural engineers have quite a lack knowledge on the proper connection and detailed joints of IBS structure, especially when subjected to dynamic/static loads such as earthquake, wind, vehicle, machinery and so forth. The loop connection considered as a conventional connection is the most interesting precast wall-to-wall connection in construction. However, this study presents a unique method for connecting two adjacent precast wall panels by using two steel U-shaped channels which are attached in the side of walls and tied together as male and female joints by using bolts and nuts make proper integrity of connection. A U-shaped rubber is implemented between the two channels in order to dissipate vibration effect in structure. The results of this study consist of the loading from the actuator, the displacement at the connection of the different LVDTs at different levels, and the crack pattern at the ultimate failure of the specimen. Upon collecting and analyzing the load test data from the data logger, the load versus displacement curves are plotted to study the actual behavior of the connection under axial, shear and flexural loads. Furthermore, the results of experimental tests showed that precast wall-to-wall equipped with U-shaped steel channel is capable of exceeding the capacity of precast walls subjected to lateral load, thereby improving its flexibility behavior in all directions. The average deformation of the proposed connection in all the LVDs was nearly 3 and 1.5 times greater than the loop connection. Additionally, the maximum average relative rotation deformation of the proposed connection in all LVDs is nearly 36% greater than the loop connection, which means that the U-shaped steel channel connection is more flexible.

Observational Evidence of Interchange Reconnection between a Solar Coronal Hole and a Small Emerging Active Region

Abstract In this Letter, we present a case study of interchange reconnection between a coronal hole (CH) and a small emerging active region. The small active region emerges at the edge of the CH. Following the emergence of the small active region, the expansion of the arcade loops connecting the negative and the positive polarities of the active region can be clearly seen in 211 and 171 Å observations. During the emergence, the active region develops loop connections to the boundary of the CH, leading to its retreat. The latter has fast and slow phases at speeds of about 2.3 km s−1 and 0.4 km s−1, respectively. By the end, these newly formed closed loops occupy most of the pre-emergence CH. From the line-of-sight magnetograms observed by Solar Dynamics Observatory/Helioseismic and Magnetic Imager, the magnetic polarity in the CH is mainly positive and the leading sunspot of the active region has negative polarity. It is consistent with the condition of interchange reconnection. Moreover, the potential field source surface model is used to extrapolate the coronal magnetic fields. From a sequence of extrapolation potential fields, it is clear that the open fields in the CH close down, and the closed field at the east of the active region becomes an open field. These observations and the extrapolations of the potential fields suggest that interchange reconnection occurs between the CH and the small emerging active region and is driven by the flux emergence process.

Models for basic warp knitted fabrics Part II: single guide bar fabrics (closed-lap and open-lap)

Warp knitted fabrics are mainly used as household goods, technical textiles, medical textiles, etc. Modeling of these fabrics is necessary for predicting the desired technical or medical functions beforehand. In this context, the present series of papers is devoted to the modeling of basic warp knitted fabrics. In this, Part II of this series, models for single guide bar fabrics are created. There are mainly two types of single bar fabrics, namely closed-lap and open-lap single bar fabrics. Structures are also changed by having different lapping movements up to the five needle spaces. In this work, 1 and 1, 2 and 1, 3 and 1, 4 and 1 closed-lap and 1 and 1, 2 and 1, 3 and 1 open-lap single bar warp knitted fabrics are considered. During modeling, the loop leanings in the course-wise direction are considered, curvature equalities at the loop parts are attained as much as possible, two connected parabolas are taken as the fabric plane model of the loop connection part, loop heads are taken as parametric ellipses in two dimensions and the remaining loop parts are modeled by wrapping parabolic or cubic curves on imaginary cylindrical or conical objects. The models created are versatile and they can be changed and used for special cases. The models created are drawn to scale by using the 3DS-MAX computer graphical program. At first glance, it is seen that the shapes obtained by the models are similar to the ones that can be observed in real samples.

Models for basic warp knitted fabrics Part III: the two guide bar fabrics (Double Tricot, Locknit, Reverse Locknit, Satin, Sharkskin)

Two guide bar warp knitted fabrics are used as technical textile applications nowadays. In this, Part III of these series of papers, models for basic two guide bar warp knitted fabrics are created and given based on Parts I and II. Modeling of warp knitted fabrics started in the 1960s with some basic geometrical models and it was continued with using Non Uniform Basis Spline (NURBS) curves and surfaces. There were discontinuities in the loop parts in early created geometrical models and the NURBS models needed some control points from some sources. In this work instead of using NURBS curves, modeling of warp knitted fabric is attempted by using known curves. During creation of the models, curvature equalities are attained as much as possible, loop connection parts are modeled by having two continuously connected parabolas for the Double Tricot fabric and the loop connection parts of the other two bar fabrics are obtained by applying a sinus square curve to the connection part of the Double Tricot fabric. The models created are versatile and they can be changed and used for special cases. Models created are drawn to scale by using the 3DS-Max Computer Graphical Program. At first glance, it is seen that the model shapes are similar to the real fabric structures, which can be observed on photographs of them.

RED-Net: A Recurrent Encoder–Decoder Network for Video-Based Face Alignment

We propose a novel method for real-time face alignment in videos based on a recurrent encoder–decoder network model. Our proposed model predicts 2D facial point heat maps regularized by both detection and regression loss, while uniquely exploiting recurrent learning at both spatial and temporal dimensions. At the spatial level, we add a feedback loop connection between the combined output response map and the input, in order to enable iterative coarse-to-fine face alignment using a single network model, instead of relying on traditional cascaded model ensembles. At the temporal level, we first decouple the features in the bottleneck of the network into temporal-variant factors, such as pose and expression, and temporal-invariant factors, such as identity information. Temporal recurrent learning is then applied to the decoupled temporal-variant features. We show that such feature disentangling yields better generalization and significantly more accurate results at test time. We perform a comprehensive experimental analysis, showing the importance of each component of our proposed model, as well as superior results over the state of the art and several variations of our method in standard datasets.

Automatic body measurement based on slicing loops

PurposeThe automatic body measurement is the key of tailoring, mass customization and fit/ease evaluation. The major challenges include finding the landmarks and extracting the sizes accurately. The purpose of this paper is to propose a new method of body measurement based on the loop structure.Design/methodology/approachThe scanned human model is sliced equally to layers consist of various shapes of loops. The semantic feature analysis has been regarded as a problem of finding the points of interest (POI) and the loop of interest (LOI) according to the types of loop connections. Methods for determining the basic landmarks have been detailed.FindingsThe experimental results validate that the proposed methods can be used to locate the landmarks and to extract sizes on markless human scans robustly and efficiently.Originality/valueWith the method, the body measurement can be quickly performed with average errors around 0.5 cm. The results of segmentation, landmarking and body measurements also validate the robustness and efficiency of the proposed methods.

Diversity in αβ and βα Loop Connections in TIM Barrel Proteins: Implications for Stability and Design of the Fold.

The (βα)8/TIM barrel is one of the most common folds of known protein structures facilitating diverse catalytic functions. The fold is formed by the repetition of the basic βαβ building block in which the β-strands are followed by α-helices eight times alternating in sequence and structure. αβ and βα loops connecting α-helices to the β-strands and the β-strands to the α-helices contribute to stability and function, respectively, an inherent imposition by the TIM barrel architecture itself. In this study, αβ and βα loops from a data set of 430 non-redundant, high-resolution triosephosphate isomerase (TIM) barrels bearing sequence homology of <30% were analyzed for their amino acid propensities, sequence profiles, and positional preferences of amino acids. While the distribution of short connections is significantly higher in αβ loops, there appears to be no such preference in βα loops. Glycine, proline, lysine, and arginine tend to show greater preference to occur in αβ loops, whereas serine, threonine, cysteine, tryptophan, and histidine occur more frequently in βα loops. In addition, striking dissimilarities in sequence and positional preferences of amino acids, especially, in short, αβ and βα loops are observed. Together, the analysis suggests the role for short loops and charged residues in promoting both non-polar and polar interactions and in β strand registry. The observed diversity, perhaps, dictates the distinct role of αβ and βα loops in stability and function, respectively. In summary, the overall observations and reasoning, in addition to steering protein engineering efforts on TIM barrel design and stabilization can provide the basis for incorporating consensus loop sequences for designing independently folding βαβ modules.

Tensile capacity of loop connections grouted with concrete or mortar

This paper presents a study of grout failure in symmetric U-bar loop connections loaded in tension, with focus on the performance of two grouting materials – concrete and mortar. The study contains an experimental investigation as well as a rigid-plastic modelling of the tensile capacity. The test specimens consisted of symmetric ‘2-on-2’ loop connections transversely reinforced with a double T-headed rebar. The amount of transverse reinforcement was varied, including the limiting cases of specimens with no transverse reinforcement, as well as connections with sufficient transverse reinforcement to allow yielding of the U-bars. The experimental work showed that connections grouted with concrete performed better than the connections grouted with mortar. In the theoretical models, the difference in tested capacity is explained by the difference in the internal angle of friction and in the softening behaviour of concrete as compared with mortar.

Optimal filtering correction for marine dynamical positioning control system

The paper focuses on the problem of control law optimization for marine vessels working in a dynamical positioning (DP) regime. The approach proposed here is based on the use of a special unified multipurpose control law structure constructed on the basis of nonlinear asymptotic observers, that allows the decoupling of a synthesis into simpler particular optimization problems. The primary reason for the observers is to restore deficient information concerning the unmeasured velocities of the vessel. Using a number of separate items in addition to the observers, it is possible to achieve desirable dynamical features of the closed loop connection. The most important feature is the so-called dynamical corrector, and this paper is therefore devoted to solving its optimal synthesis in marine vessels controlled by DP systems under the action of sea wave disturbances. The problem involves the need for minimal intensity of the control action determined by high frequency sea wave components. A specialized approach for designing the dynamical corrector is proposed and the applicability and effectiveness of the approach are illustrated using a practical example of underwater DP system synthesis.

A new precast wall connection subjected to monotonic loading

Final construction project cost is significantly determined by construction rate. The Industrialized Building System (IBS) was promoted to enhance the importance of prefabrication technology rather than conventional methods in construction. Ensuring the stability of a building constructed by using IBS is a challenging issue. Accordingly, the connections in a prefabricated building have a basic, natural, and essential role in providing the best continuity among the members of the building. Deficiencies of conventional precast connections were observed when precast buildings experience a large induced load, such as earthquakes and other disasters. Thus, researchers aim to determine the behavior of precast concrete structure with a specific type of connection. To clarify this problem, this study investigates the capacity behavior of precast concrete panel connections for industrial buildings with a new type of precast wall-to-wall connection (i.e., U-shaped steel channel connection). This capacity behavior is compared with the capacity behavior of precast concrete panel connections for industrial buildings that used a common approach (i.e., loop connection), which is subjected to monotonic loading as in-plane and out-of-plane loading by developing a finite element model. The principal stress distribution, deformation of concrete panels and welded wire mesh (BRC) reinforcements, plastic strain trend in the concrete panels and connections, and crack propagations are investigated for the aforementioned connection. Pushover analysis revealed that loop connections have significant defects in terms of strength for in-plane and out-of-plane loads at three translational degrees of freedom compared with the U-shaped steel channel connection.

Information processing in the hemisphere of the cerebellar cortex for control of wrist movement.

A region of cerebellar lobules V and VI makes strong loop connections with the primary motor (M1) and premotor (PM) cortical areas and is assumed to play essential roles in limb motor control. To examine its functional role, we compared the activities of its input, intermediate, and output elements, i.e., mossy fibers (MFs), Golgi cells (GoCs), and Purkinje cells (PCs), in three monkeys performing wrist movements in two different forearm postures. The results revealed distinct steps of information processing. First, MF activities displayed temporal and directional properties that were remarkably similar to those of M1/PM neurons, suggesting that MFs relay near copies of outputs from these motor areas. Second, all GoCs had a stereotyped pattern of activity independent of movement direction or forearm posture. Instead, GoC activity resembled an average of all MF activities. Therefore, inhibitory GoCs appear to provide a filtering function that passes only prominently modulated MF inputs to granule cells. Third, PCs displayed highly complex spatiotemporal patterns of activity, with coordinate frames distinct from those of MF inputs and directional tuning that changed abruptly before movement onset. The complexity of PC activities may reflect rapidly changing properties of the peripheral motor apparatus during movement. Overall, the cerebellar cortex appears to transform a representation of outputs from M1/PM into different movement representations in a posture-dependent manner and could work as part of a forward model that predicts the state of the peripheral motor apparatus.

Braiding of Branches for the Fibre Composite Technology

In many areas of fiber composite technology there is a great need for a solution of how to manufacture nodal elements and/or ramifications with an optimized force flow process and by machine, i.e. economically. Examples are hubs of wind power plants, branch points in framework constructions in the building industry and air and space travel, the automotive industry, ramified vein prostheses in medical technology, or the connecting nodes of bicycle frames. Motivated by this, the potential of plant ramifications as a model for new compound fiber constructions was investigated. Ramified species with pronounced fiber matrix structure served, inter alia, as biological models. The PBG Freiburg examined tree-formed monocotyledons of the genera Dracaena and Freycinetia [1], the BTU Dresden column cacti of the genera Pilsocereus and Myrtillocactus [2]. The plants exhibit Y-shaped and T-shaped ramifications, whose angles resemble those of the ramified technical construction units that are to be optimised bionically. As the investigations confirm, the ramifications, which are nearly completely unexplored, are characterised by very interesting mechanical characteristics, like e.g. good-natured breaking behavior and good oscillation damping caused by high energy absorption, as well as a high lightweight construction potential. The results demonstrate the high potential for a successful technical transfer of the results of the proposed project.In this paper, three different types of braided branches are represented. Firstly, the aforementioned nature-inspired Y-junctions are shown. Secondly, a type of branch with a special braiding technique that allows branches with asymmetric design of the arms and a braiding technique for the automated production of loop connections is presented.

Strength of Loop Connections between Precast Bridge Decks Loaded in Combined Tension and Bending

The paper presents a study of the load-carrying capacity of loop connections subjected to combined tension and bending. For such connections, the main design challenge in practice is to obtain a load- carrying capacity that is governed by yielding of the looped reinforcing bars (i.e., the U-bars) and not by fracture of the joint concrete. Unfortunately, reliable design models serving this purpose have not yet been published. Therefore, in this paper, a design-oriented plasticity model is proposed for the calculation of the N–M interaction diagram accounting for both failure modes. The work is an extension of a model previously developed by the authors for the case of pure tension. In addition to the theoretical work, test results of connections subjected to combined tension and bending are also presented. Calculations according to the model have been compared with tests. Satisfactory agreements have been found.