Coordination sequences of crystals are of quasi-polynomial type

The coordination sequence of a graph measures how many vertices the graph has at each distance from a fixed vertex and is a generalization of the coordination number. Here it is proved that the coordination sequence of the graph obtained from a crystal is of quasi-polynomial type, as had been postulated by Grosse-Kunstleve et al. [Acta Cryst. (1996), A52, 879–889].

Analisis Gangguan Arus Hubung Singkat Trafo Distribusi 48-PT-33-7 Menggunakan ETAP (Studi Kasus Di Perumahan PT. Badak NGL)

The high frequency of short circuit current fault in power grid PT. Badak NGL Bontang in 2017 becomes a serious problem. One of them is the Short Circuit at Distribution Transformer 48-PT-33-7 which resulted in a feeder 48-FDR-33 trip and cut off the power to all connected loads. This research is conducted to know the value of short circuit current fault by manual calculation and compared with the simulation software ETAP 12.6 which made system modeling refers to real network configuration in the field. After that, ETAP conducted simulation and short circuit analysis in transformer 48-PT-33-7. The calculation result is known that the short circuit current value between manual calculation and ETAP simulation is relatively same, ie 553,8 A / 555 A (one phase to ground), 891,47A / 885 A (two phase), 918,16 A / 950 A (two phase to ground), 1029.41 A / 1022 A (three phases). From the simulation also known the coordination sequence of the protection system works properly when the fault occurs. So from these two results indicate that the installed protection system is in accordance with the standard in securing the power grid from short-circuiting current fault.

Coordination shells and coordination numbers of the vertex graph of the Ammann–Beenker tiling

The vertex graph of the Ammann–Beenker tiling is a well-known quasiperiodic graph with an eightfold rotational symmetry. The coordination sequence and coordination shells of this graph are studied. It is proved that there exists a limit growth form for the vertex graph of the Ammann–Beenker tiling. This growth form is an explicitly calculated regular octagon. Moreover, an asymptotic formula for the coordination numbers of the vertex graph of the Ammann–Beenker tiling is also proved.

A coloring-book approach to finding coordination sequences

An elementary method is described for finding the coordination sequences for a tiling, based on coloring the underlying graph. The first application is to the two kinds of vertices (tetravalent and trivalent) in the Cairo (or dual-32.4.3.4) tiling. The coordination sequence for a tetravalent vertex turns out, surprisingly, to be 1, 4, 8, 12, 16, …, the same as for a vertex in the familiar square (or 44) tiling. The authors thought that such a simple fact should have a simple proof, and this article is the result. The method is also used to obtain coordination sequences for the 32.4.3.4, 3.4.6.4, 4.82, 3.122 and 34.6 uniform tilings, and the snub-632 tiling. In several cases the results provide proofs for previously conjectured formulas.

Team Coordination Dynamics in Human-Autonomy Teaming

Project overview. The current study focuses on the nature of team coordination dynamics within all-human teams and Human-Autonomy Teams (HAT) in the context of the development of a fully-fledged synthetic agent that is a computational cognitive model for a three-agent Unmanned Aircraft System (UAS) ground crew. In this study, the relationship between team coordination dynamics and team performance within the HAT and all-human teams is considered. To serve as a teammate, the synthetic agent must be able to communicate and coordinate with its human teammates in a constructive and timely manner (Demir, McNeese, & Cooke, 2016). In this current research, there were three heterogeneous team members who communicated via a text-based communication system to photograph target waypoints. Each team member had a different role: (1) navigator – provides information regarding a flight plan with speed and altitude restrictions of each waypoint; (2) pilot – controls the UAS by adjusting its altitude and airspeed by negotiating with the photographer to take a good photo for the target waypoints; and (3) photographer – screens camera settings, and sends feedback to the other team members regarding the status of target’s photograph. At each target waypoint, this coordination sequence among the team members, called Information-Negotiation-Feedback (INF), is captured by a Kappa Score (Gorman, Amazeen, & Cooke, 2010) that describes the sequence and timing of the information coordination. Three conditions were created that manipulated the pilot role: (1) Synthetic – pilot was the synthetic agent, (2) Control – pilot was a randomly assigned participant, and (3) Experimenter – pilot was an experimenter who was highly experienced with the task and focused on pushing and pulling the information in a timely manner. Method. In this experiment, there were 30 teams (ten teams for each condition): control teams were composed of three participants randomly assigned to each role; synthetic and experimenter teams were composed of only two participants randomly assigned to the navigator and photographer roles. The experiment consisted of five missions (each 40 minutes) in which teams needed to take as many “good” photos as possible of ground targets while avoiding alarms and rule violations. Several measures were obtained from this research, including team performance scores (mission and target level), team process measures (situation awareness, process ratings, communication and coordination), and other measures (teamwork knowledge, workload, and demographics). The research reported here identifies how differences in team coordination, captured by Kappa, relate to performance of all human teams and HAT teams. In this paper, we focus on: (1) target level team performance scores calculated based on the time spent inside a target waypoint to get a good photo; and (2) two team coordination dynamics measures: stability and team communication determinism. Stability was inversely related to the largest Lyapunov Exponent which was estimated by Kappa, that is, the INF coordination sequence. Team communication determinism was estimated from communication data using Joint Recurrence Quantification Analysis (Marwan, Carmen, Thiel, & Kurths, 2007) and served as an index of flexible behavior. Results and discussion. In general, findings indicate that (1) synthetic teams were most stable, followed by experimenter teams, who were moderately stable, and control teams, who were least stable; and (2) extreme stability and instability corresponded to lower levels of performance; experimenter teams performed best, followed by control teams and, then synthetic teams. Thus, synthetic agents could be made more effective if interventions were developed to enhance the flexibility and adaptive nature of HATs (Demir, 2017).

Stepwise radial complexation from the outer layer to the inner layer of a dendritic ligand: a phenylazomethine dendrimer with an inverted coordination sequence

A meta-substituted phenylazomethine dendrimer was discovered as a dendritic ligand that sequentially coordinates to Lewis acids from the outer layer to the inner layer in a stepwise radial fashion.

Crystal chemistry of orthosilicates and their analogs: the classification by topological types of suprapolyhedral structural units

A method is developed for the analysis and classification of orthosilicates and their analogs Mx (TO4) y containing M cations and tetrahedral TO4 anions. The method uses the concepts of coordination sequence and crystal structure `reduced' graphs and is optimized for orthostructures of any complexity. First, the suprapolyhedral level of crystal structure organization was studied, where T tetrahedra were considered as templates for condensing M polyhedra, constructing as a result T polyhedral microensembles. Using this methodology, the crystal structures of 54 orthosilicates and orthogermanates were analyzed within the first 12 coordination spheres of T nodes and were arranged into 21 topological types. The topological types were expanded with the analogs found within the orthostructures of phosphates, sulfates etc. T polyhedral microensembles were used for the topological classification of reconstruction mechanisms of thermal and baric phase transitions of orthosilicates.

Coordination sequences for root lattices and related graphs

The coordination sequence