Reachability Analysis of Asynchronous Dynamic Pushdown Networks Based on Tree Semantics Approach

ADPN (Asynchronous Dynamic Pushdown Networks) are an abstract model for concurrent programs with recursive procedures and dynamic thread creation. Usually, asynchronous dynamic pushdown networks are described with interleaving semantics, in which the backward analysis is not effective. In order to improve interleaving semantics, tree semantics approach was introduced. This paper extends the tree semantics to ADPN. Because the reachability problem of ADPN is also undecidable, we address the context-bounded reachability problem and provide an algorithm for backward reachability analysis with tree-based semantics Approach

Empirical study on flow experience in China tourism e-commerce market

Purpose: While tourism e-commerce develops rapidly in China, these channels are truly new to both web providers and web consumers, understanding the nature of these media attaches greater importance. This study investigates the mediation effects of flow experience on the relationship between motivation and behavior intention in tourism e-commerce. Design/methodology/approach: Based on the technology acceptance model, an empirical study is designed to test this relationship. We estimated the measurement model with 13 manifest indicators and 4 latent constructs by CFA to assess the reliability and validity of the construct measures, then tested hypotheses by OLS regression and a formal three-step mediation procedure. Findings: Overall, the results reveal that trust is incorporated in motivation and play it’s role together with other motivations; telepresence and concentration are confirmed in flow experience, and both partially mediated the relationship. Research limitations/implications: This study demonstrates that to improve consumers’ usage adoption, marketers should pay much attention to not only consumers’ motivation but also the areas such as flow experiencePeer Reviewe

Development and evaluation of new silica based polar and / or mixed modal stationary phases for HPLC

Vier stationäre Phasen wurden synthetisiert, deren Ligand Hydroxyl- sowie Sulfid- oder Sulfoxid-Gruppen enthielten. 2-Mercaptoethanol (ME-Phase) und 1-Thioglycerin (TG-Phase) wurden auf vinylisiertem Silica durch eine radikalische Additionsreaktion immobilisiert. Anschließend wurde eine on-phase Oxidation mit Wasserstoffperoxid durchgeführt, wobei Sulfid-Gruppen in Sulfoxid-Gruppen umgewandelt wurden (MEO und TGO Phasen). Diese neu entwickelte diol-Typ stationäre Phasen zeigte eine sehr gut Eignung für die Trennungen von Nukleosiden, Nukleobasen und wasserlösliche Vitamine im HILIC Modus. Mehr polarer Phasen zeigten eine stärkere Retention von polaren Verbindungen, wobei die Sulfoxide Funktionalität in den Ligand sehr positiv auf die Generierung der Retention und Selektivität wirkten. Im Vergleich zu kommerziellen HILIC Säulen wurden komplementäre Selektivitäten gefunden, die auf Unterschiede im Retentionsmechanismus hindeuteten. Weiterhin waren die entwickelte Diol-Typ Phasen auch im Reversed-Phase (RP) Modus mit Bezug auf eine CH2-Inkrement Selektivität verwendbar(Multimodale Trennungsfähigkeit). Silanol-Aktivität hatte ausgeprägte Effekte auf Retention und Selektivität im HILIC Modus und das Ausmaß der Antwort war abhängig von der Art des Analytes. Im HILIC Modus silanophile Interaktionen können als primäre Retentionsmechanismus auf silica-basierter stationären Phasen, vor allem für geladene und beladbare Verbindungen. Die Art der protischen Modifier (Wasser, 1,2-Ethandiol, Methanol, Ethanol) war sehr effektive auf Retention und Selektivität und das Ausmaß des Effekts war hierbei stark von der Polarität des eingesetzten Alkohol-Modifiers bestimmt und stieg die Retention tendenziell in der Reihenfolge 1,2-Ethandiol < Methanol < Ethanol an. Neben diesem Effekt auf die Retention, war chromatographische Selektivität auch deutlich von der Art des Alkohol-Modifiers beeinflusst werden. Selbst unter isoelutropen Bedingungen (vgl. mitwässrigen HILIC-Eluenten) zeigten sich mit nicht-wässriger mobiler Phase unterschiedliche Trennergebnisse, bis hin zur Umkehr von Elutionsreihenfolgen. Außerdem waren die Menge von organischem Solvent, die Art und Menge der Salze, pH-Wert und die Temperatur der Säule effektive Parametern zum Optimierung der Trennung im HILIC Modus. Der HILIC Retentionsmechanismus zeigt komplexe Eigenschaften und es wird angenommen, dass die hydrophilen Interaktionen aus Verteilungs- und schwache Adsorptionsinteraktionen wie z.B. Wasserstoffbrücken, Dipol-Dipol-Wechselwirkungen induziert durch direkte Analyte-Liganden-Wechselwirkungen, Analyte-Solvatationsschicht auf der Oberfläche und/oder Analyte-Silanol bestehen. Bei geladenen stationären Phasen wurden die elektrostatischen Wechselwirkungen von hydrophilen Interaktionen überlagert.Four stationary phases having non-charged ligands with hydroxyl as well as sulfide- or sulfoxide-groups bonded to silica were prepared. 2-mercaptoethanol (ME phase) and 1-thioglycerol (TG phase) were immobilized on vinylised silica by radical addition. Subsequent on-phase oxidation of the embedded sulphide groups with hydrogen peroxide delivered sulfoxide-groups (MEO and TGO phases). These new developed diol-type stationary phases offered HILIC chromatographic selectivity towards the separation of nucleosides, nucleobases and water soluble vitamins. Higher Phase polarity caused a stronger retention of polar compounds and sulfoxide functionality in the ligand was especially useful to change HILIC characterisation of phases. Compared to commercial diol-type HILIC packings complementary selectivity was found which may be an indication for different retention mechanisms being at work. The developed diol-type phases delivered also noticeable CH2-increment selectivity (multimodal separation capability). Silanol activity had definite effects on retention and selectivity in the HILIC elution mode and the extent of response was depending on the type of analytes (acids, bases, non-charged). In the HILIC mode, silanophilic interactions may become the main retention mechanism on silica-based polar phases, especially for charged and chargeable compounds. The type of protic modifier (water, 1,2-ethanediol, methanol, ethanol) had significant effect on HILIC retention and the polarity of these protic modifiers adopted a primary role in determining the extent of retention and, generally, increased retention was found in the order water < 1,2-ethanediol < methanol < ethanol. Besides the effect on retention, chromatographic selectivity was also affected by the type of alcohol modifier and under isoelutropic conditions compared to an aqueous HILIC eluent the selectivity can be changed up to an inverted elution order. Additionally, the amount of organic solvent, the nature and amount of salt, pH value and column temperature were all effective to optimise HILIC separations. The retention mechanisms were quite complex in HILIC. It was supposed that the hydrophilic interactions were composed of partitioning and weak adsorption interactions which could be developed by direct solute-ligand interactions, solute-solvent shell on the surface, and/or solute-silanol interactions. For charged packings, electrostatic interactions (attractive or repulsive) can be easily superimposed on the hydrophilic interactions

The Effect of Indium Concentration on the Structure and Properties of Zirconium Based Intermetallics: First-Principles Calculations

The phase stability, mechanical, electronic, and thermodynamic properties of In-Zr compounds have been explored using the first-principles calculation based on density functional theory (DFT). The calculated formation enthalpies show that these compounds are all thermodynamically stable. Information on electronic structure indicates that they possess metallic characteristics and there is a common hybridization between In-p and Zr-d states near the Fermi level. Elastic properties have been taken into consideration. The calculated results on the ratio of the bulk to shear modulus (B/G) validate that InZr3 has the strongest deformation resistance. The increase of indium content results in the breakout of a linear decrease of the bulk modulus and Young’s modulus. The calculated theoretical hardness of α-In3Zr is higher than the other In-Zr compounds

(E)-3-(2,4-Dimeth­oxy­phen­yl)-1-(3,4,5-trimeth­oxy­phen­yl)prop-2-en-1-one

In the title chalcone derivative, C20H22O6, the dihedral angle between the mean planes of the benzene rings is 15.77 (6)°. The H atoms of the central C=C double bond are in a trans configuration. There are a number of C—H⋯O interactions and a C—H⋯π interaction present in the crystal structure

SDP-Based Robust Formation-Containment Coordination of Swarm Robotic Systems with Input Saturation

From Springer Nature via Jisc Publications RouterHistory: received 2020-08-24, accepted 2021-03-12, registration 2021-03-12, pub-electronic 2021-04-19, online 2021-04-19, pub-print 2021-05Publication status: PublishedFunder: Engineering and Physical Sciences Research Council; doi: https://doi.org/10.13039/501100000266; Grant(s): EP/R026084/1Funder: Engineering and Physical Sciences Research Council; doi: https://doi.org/10.13039/501100000266; Grant(s): EP/P01366X/1Funder: Horizon 2020; doi: https://doi.org/10.13039/501100007601; Grant(s): 899520Abstract: There are many potential applications of swarm robotic systems in real-world scenarios. In this paper, formation-containment controller design for single-integrator and double-integrator swarm robotic systems with input saturation is investigated. The swarm system contains two types of robots—leaders and followers. A novel control protocol and an implementation algorithm are proposed that enable the leaders to achieve the desired formation via semidefinite programming (SDP) techniques. The followers then converge into the convex hull formed by the leaders simultaneously. In contrast to conventional consensus-based formation control methods, the relative formation reference signal is not required in the real-time data transmission, which provides greater feasibility for implementation on hardware platforms. The effectiveness of the proposed formation-containment control algorithm is demonstrated with both numerical simulations and experiments using real robots that utilize the miniature mobile robot, Mona