Hierarchical Counterpart Research Articles

In-plane crushing behavior and energy absorption of a novel graded honeycomb from hierarchical architecture

Nature's bio-organisms are typically hybrid structures composed of hierarchical and functionally graded micro-architectures, which are lightweight and of high mechanical performances. Inspired by nature, an innovative graded hierarchical honeycomb is proposed in this study to enhance its crashworthiness behaviors. The structure is created by replacing cell walls of regular honeycombs with triangular and hexagonal sub-structures and varying the hierarchical length ratio in each layer. The in-plane crushing performances of the graded hierarchical honeycombs are comprehensively analyzed and compared with their uniform hierarchical counterpart. The former exhibits a progressive deformation model under different impact velocities and three plateau stages can be observed under in-plane crushing loads through theoretical predictions. The triangular sub-structure presents better energy absorption than the hexagonal sub-structure, and its specific energy absorption is enhanced by up to 32.2% as compared to the uniform hierarchical honeycomb. The present study suggests that the combination of hierarchy and gradient is an effective strategy to improve the dynamic crushing behaviors of honeycombs, which can be further explored in protective devices to enhance their impact resistance.

Zn-P Co-Modified Hierarchical ZSM-5 Zeolites Directly Synthesized via Dry Gel Conversion for Enhanced Methanol to Aromatics Reaction

A unique method to prepare Zn-P co-modified hierarchical ZSM-5 zeolites was developed. The ZSM-5 zeolite was directly synthesized by a dry gel conversion without adding any templates or seeds. Afterwards, the hierarchical structure was endowed to the ZSM-5 zeolite by the sequential desilication-dealumination. Zn and P species were then introduced into the hierarchical ZSM-5 zeolites by the impregnation method and their activity in methanol to aromatics process was investigated. It was found that the Zn-P co-modified hierarchical ZSM-5 zeolites possessed more Zn-related Lewis acid sites, and the ratio of Zn(OH)+/ZnO was increased. The catalytic evaluation results revealed that the benzene, toluene and xylene (BTX) and aromatics selectivity were significantly improved from 20.59% and 29.41% of pristine ZSM-5 zeolite to 28.12% and 41.88% of Zn-P co-modified hierarchical counterpart (1.5Zn0.3P/HZSM-5), respectively. Owing to the introduced highly stable Zn-P co-modified hierarchical structures, the lifetime (conversion not less than 99%) of ZSM-5 zeolite during methanol to aromatics reaction was increased from 6 h to 18 h.

Sustainable approach for the development of durable superhydrophobic metallic surfaces

In the present work, we devised a facile, and environmental imprinting and hot-water treatments for developing a durable self-cleaning aluminum surface. The micro and nanostructured surfaces were composed of pillars and ellipsoidal flakes, respectively. The fluorination (vapor deposition) of surfaces imparted superhydrophobicity (θs > 150°), with high adhesion observed for micro-patterned surface, while nano and hierarchical surfaces exhibited low hysteresis and tilting angles (θ < 5°). The nanostructured (ΔE=-0.3J/m) surface has shown the prevalence of stable Cassie state compared to hierarchical (ΔE=-0.07J/m) counterpart. The nanostructured surface has also exhibited higher durability under static and dynamic conditions than the hierarchical counterpart.

Synthesis of impregnated Ni(0) zeolite ZSM-5 as catalyst for carboxylation reaction of acetylene with CO2

Conversion of carbon dioxide (CO2) into other compounds has become very advantageous because of the abundance in the atmosphere. However, carbon dioxide (CO2) is thermodynamically and kinetically stable so it needs low valence metal such as Ni(0) to be activated and react with other compounds. In this study, nickel metal-impregnated ZSM-5 was prepared as heterogeneous catalyst for carboxylation reaction of acetylene with carbon dioxide. Microporous and hierarchical ZSM-5 were synthesized using single template and double template, respectively. X-Ray Diffraction (XRD) characterization results show that ZSM-5 material with high crytallinity was successfully synthesized. Scanning Electron Microscopy (SEM) images show ZSM-5 has hexagonal coffin-like morphology. Brunauer-Emmett-Teller (BET) surface area analysis proves that the ZSM-5 has combination of micro and meso-sized pores (hierarchical pores). The elemental analysis using Atomic Absorption Spectroscopy (AAS) gives nickel content of 1.9 % in microporous ZSM-5 and 2.1 % in hierarchical ZSM-5. HPLC analysis show new peak is observed at retention time of 3.6 minutes for carboxylation reaction of acetylene (CO2: acetylene of 0.2:0.8) with optimum condition at 12 h and 80 °C when using microporous Ni/ZSM-5 or hierarchical counterpart as catalyst.

Catalytic deoxygenation of vapors obtained from ablative fast pyrolysis of wheat straw using mesoporous HZSM-5

Steam treated HZSM-5 with different Si/Al ratios were tested as catalysts for the upgrading of wheat straw pyrolysis vapors and their performance was compared to hierarchical counterparts, which were prepared by desilication followed by acid washing. Pyrolysis vapors were generated in an ablative system, hot gas filtered, and upgraded in an ex-situ catalyst bed to remove oxygen functionalities and reduce the oils' total acid number (TAN). Besides elemental analysis and TAN, the collected liquids were analyzed for water, chemical composition by gas chromatography mass spectrometry with flame ionization detection (GC–MS/FID), size exclusion chromatography (SEC), thermogravimetric analysis (TGA), and selectively by 1H nuclear magnetic resonance (NMR), 13C NMR, and two-dimensional heteronuclear single-quantum correlation (2D HSQC) NMR. Hierarchical and conventional catalysts were analyzed with X-ray fluorescence (XRF), ammonia temperature-programmed desorption (NH3-TPD) and ethylamine TPD, N2 and Ar-physisorption, transmission electron microscopy (TEM) and X-ray diffraction (XRD) to investigate changes induced by the desilication process. In addition, samples were analyzed after several reaction and regeneration cycles to investigate catalyst stability. The hierarchical samples showed an increased coking propensity compared to their parent version. The introduction of mesopores after desilication of HZSM-5 with molar Si/Al ratios of 29 and 39 lead to prolonged activity in deoxygenation and improved carbon recovery in the collected oil fractions compared to the parent counterparts. The results indicate that mild deoxygenation may be a viable way of pretreating pyrolysis oil before co-processing with fossil oil in refineries.

Hierarchical joint remote state preparation in noisy environment

A novel scheme for quantum communication having substantial applications in practical life is designed and analyzed. Specifically, we have proposed a hierarchical counterpart of the joint remote state preparation (JRSP) protocol, where two senders can jointly and remotely prepare a quantum state. One sender has the information regarding amplitude, while the other one has the phase information of a quantum state to be jointly prepared at the receiver's port. However, there exists a hierarchy among the receivers, as far as powers to reconstruct the quantum state is concerned. A 5-qubit cluster state has been used here to perform the task. Further, it is established that the proposed scheme for hierarchical JRSP (HJRSP) is of enormous practical importance in critical situations involving defense and other sectors, where it is essential to ensure that an important decision/order that can severely affect a society or an organization is not taken by a single person, and once the order is issued all the receivers don't possess an equal right to implement it. Further, the effect of different noise models (e.g., amplitude damping (AD), phase damping (PD), collective noise and Pauli noise models) on the HJRSP protocol proposed here is investigated. It is found that in AD and PD noise models a higher power agent can reconstruct the quantum state to be remotely prepared with higher fidelity than that done by the lower power agent(s). In contrast, the opposite may happen in the presence of collective noise models. We have also proposed a scheme for probabilistic HJRSP using a non-maximally entangled 5-qubit cluster state.

Bifunctional Cu/H-ZSM-5 zeolite with hierarchical porosity for hydrocarbon abatement under cold-start conditions

A key target to reduce current hydrocarbon emissions from vehicular exhaust is to improve their abatement under cold-start conditions. Here, we demonstrate the exceptional properties of a hierarchical Cu/H-ZSM-5 zeolite-based system as a catalytic trap. The largely increased external surface area coupled with the preserved intrinsic properties attainable upon alkaline treatment and subsequent acid washing of a conventional ZSM-5 zeolite enable an improved dispersion of copper species in the hierarchical counterpart. The impact of post-synthetic modification on the preparation of copper-containing ZSM-5 is clearly revealed by XRD, N2 sorption, FTIR, NH3-TPD, TEM, SEM, and HAADF-STEM. By providing stronger adsorption sites, the introduction of copper species improves the retention of propene and toluene with respect to the protonic zeolites, and enables their further conversion to carbon dioxide and water rather than their emission in the exhaust. The equivalent adsorption capacity and improved oxidation activity and lower susceptibility to deactivation exhibited by the hierarchical Cu/H-ZSM-5 catalyst vis-a-vis its conventional counterpart yield a superior bifunctional catalyst able of reach full hydrocarbon conversion under realistic operating conditions.

Human performance under two different command and control paradigms

The paradoxical behaviour of a new command and control concept called Network Enabled Capability (NEC) provides the motivation for this paper. In it, a traditional hierarchical command and control organisation was pitted against a network centric alternative on a common task, played thirty times, by two teams. Multiple regression was used to undertake a simple form of time series analysis. It revealed that whilst the NEC condition ended up being slightly slower than its hierarchical counterpart, it was able to balance and optimise all three of the performance variables measured (task time, enemies neutralised and attrition). From this it is argued that a useful conceptual response is not to consider NEC as an end product comprised of networked computers and standard operating procedures, nor to regard the human system interaction as inherently stable, but rather to view it as a set of initial conditions from which the most adaptable component of all can be harnessed: the human.

Dynamic schedule execution in an agent based holonic manufacturing system

The present paper deals with the negotiation based task allocation to the resources for preparing dynamic scheduling in an agent based holonic control framework. The scheduling priority is developed by Multi Objective Optimization on the basis of Ratio Analysis (MOORA) technique under Fuzzy Multi Criteria Decision Making (FMCDM) environment considering several attributes. The well-known Contract Net Protocol (CNP) is followed for the purpose of task allocation by negotiation and cooperation, where message based communication is accomplished by eXtensible markup language (XML) using J2EE. Different Document Type Definitions (DTDs) are developed for intended applications. Necessary modifications in the scheduling arising out of changes in the volume-mix are made by a distributed cooperative problem-solving algorithm to meet the demand without violating the deadline. The algorithm is implemented using HTML code in front-end with Java Server Page (JSP) through Apache Tomcat 6.02 server. It is advocated that the cooperation based teamwork coupled with higher flexibility and agility is the key to success to remain unperturbed and provide reasonably good solution in the face of disturbances and stands superior to its hierarchical counterpart.

An Empirical Evaluation of Network Centric Team Organisation versus Hierarchical Team Organisation

Traditional hierarchical command and control was pitted against a network centric alternative on a common task played thirty times by two teams. Multiple regression was used to undertake a simple form of time series analysis. Whilst the network centric condition ended up being slightly slower than its hierarchical counterpart, it was able to balance and optimise three other factors: team cohesion, enemies neutralized and attrition.

A field study of team working in a new human supervisory control system

This paper presents a case study of an investigation into team behaviour in an energy distribution company. The main aim was to investigate the impact of major changes in the company on system performance, comprising human and technical elements. A socio-technical systems approach was adopted. There were main differences between the teams investigated in the study: the time of year each control room was studied (i.e. summer or winter), the stage of development each team was in (i.e. < 3 months or > 10 months), and the team structure (i.e. hierarchical or heterarchical). In all other respects the control rooms were the same: employing the same technology and within the same organization. The main findings were: the teams studied in the winter months were engaged in more ‘planning’ and ‘awareness’ type of activities than those studies in the summer months. Newer teams seem to be engaged in more sharing of information than older teams, which may be indicative of the development process. One of the hierarchical teams was engaged in more ‘system-driven’ activities than the heterarchical team studied at the same time of year. Finally, in general, the heterarchical team perceived a greater degree of team working culture than its hierarchical counterparts. This applied research project confirms findings from laboratory research and emphasizes the importance of involving ergonomics in the design of team working in human supervisory control.

Statistical grammar inference

Language can be talked, written, printed, or encoded in numerous different ways. As any form of communication, each of these codings can be analyzed statistically for the purpose of comparative judgment and predicting power. Early proposals of language models such as Markov models, N-gram models [C. E. Shannon, Bell Syst. Tech. J. 27(3), 379–423 (1948)] although efficient in practice, have been quickly refuted in theory since they are unable to capture long distance dependencies or to describe hierarchically the syntax of natural languages. Stochastic context-free grammar [T. Booth, in 10th Annual IEEE Symp. on Switching and Automata Theory (1969)] is a hierarchical model that assigns a probability to each context-free rewriting rule. However, none of such proposals perform as well as the simpler Markov models because of the difficulty of capturing lexical information [Jelinek etal., Tech. Rep. RC 16374 (72684), IBM, Yorktown Heights, NY 10598 (1990)] [K. Lari and S. J. Young, Comput. Speech Lang. 4, 35–56 (1990)] This is the case even if supervised training is used [F. Pereira and Y. Schabes, in ACL ’1992]. Stochastic lexicalized tree-adjoining grammar (SLTAG) has been recently suggested as the basis for training algorithm [Y. Schabes, in COLING ’1992]. The parameters of a SLTAG correspond to the probability of combining two structures each one associated with a word. This system reconciles abstract structure and concrete data in natural language processing since it is is lexically sensitive and yet hierarchical. The need for a lexical and still hierarchical statistical language model is partially corroborated by preliminary experiments which show that SLTAG enable better statistical modeling than its hierarchical counterpart, stochastic context-free grammars. The experiments also show that SLTAG is capable of capturing lexical distributions as well as bigram models while maintaining the hierarchical nature of language.