Prudent constraint-handling technique for multiobjective propeller optimisation

The paper presents an alternative constraint-handling technique that converts a nonlinear constrained programming problem into an unconstrained multi-objective optimisation problem. The technique is derived from the behavioural memory constraint-handling method, which was originally implemented for single-objective optimisation with genetic algorithms. We compare our presented technique with two other popular constraint-handling concepts and demonstrate its superiority over them when applied to a propeller optimisation problem. We conclude that the multi-objective behavioural memory constraint-handling technique conjugated with the non-dominated sorting genetic algorithm (NSGA-II) is a prudent method to apply to problems with an infeasible initial design and where constraints have a natural order of satisfaction, which, if not conformed to, would lead to unrealistic designs that impair the search by GA.     

Nonparametric inference based on panel count data

Panel count data usually refer to data arising from studies on recurrent events in which the subjects under study are followed or observed only periodically rather than continuously. In such situations, an objective of interest is about the occurrence of some events that can occur multiple times or repeatedly and the studies resulting in this type of information are often referred to as event history studies. There are many fields such as medical studies, reliability experiments and social sciences wherein panel count data are encountered commonly. This article reviews basic concepts about panel count data, some common issues and questions of interest regarding them as well as the corresponding statistical procedures that are suitable for their analysis. In particular, we will discuss an estimation of the mean function of the underlying counting process characterizing the occurrence of the events, comparison of several processes and analysis of multiple state panel count data. Some discussion is also presented of situations involving dependent or informative observation processes.     

Synthesis of minimal-size ZnO nanoparticles through sol–gel method: Taguchi design optimisation

Zinc oxide (ZnO) has excellent potential to be used in water and wastewater treatment, either as a photocatalyst or in membrane incorporation. In this work, the synthesis of smaller ZnO NPs through a sol–gel approach was enhanced by applying Taguchi design. Recent work on the synthesis of ZnO NPs was optimised to ensure relatively smaller sized particles were obtained. Several parameters of the synthesis process, such as molar ratio of starting materials, molar concentration and calcination temperature, were selected as they have the dominant effects on the particle size of ZnO NPs. Each of these factors was studied at three levels. Various analyses such as ANOVA, model adequacy check and numerical optimisation were performed to validate the predicted optimal model. As a result, the optimum conditions were estimated at a molar ratio of 50:50, an oxalic acid molar concentration of 0.1 M and a calcination temperature of 400 °C. Experiments were performed to validate the model at the selected conditions and the particle size was around 20 ± 2 nm according to XRD analysis, which was in good agreement with the predicted size of 19.8 nm. In addition, the actual size of the synthesised NPs was confirmed by TEM analysis, with the average size of 13 ± 5 nm. Hence, the Taguchi design was an essential tool in the optimisation of ZnO NP synthesis process with fewer experimental runs and relatively low cost approach.     

Human tissue allograft processing: impact on in vitro and in vivo biocompatibility

This work investigates the impact of chemical and physical treatments on biocompatibility for human bone/tendon tissues. Nontreated and treated tissues were compared. In vitro testing assessed indirect and direct cytotoxicity. Tissues were subcutaneously implanted in rats to assess the immunological, recolonization, and revascularization processes at 2–4 weeks postimplantation. No significant cytotoxicity was found for freeze-dried treated bones and tendons in comparison to control. The cellular adhesion was significantly reduced for cells seeded on these treated tissues after 24 h of direct contact. A significant cytotoxicity was found for frozen treated bones in comparison to freeze-dried treated bones. Tissue remodeling with graft stability, no harmful inflammation, and neo-vascularization was observed for freeze-dried chemically treated bones and tendons. Frozen-treated bones were characterized by a lack of matrix recolonization at 4 weeks postimplantation. In conclusion, chemical processing with freeze-drying of human tissues maintains in vitro biocompatibility and in vivo tissue remodeling for clinical application.     

Convex resource allocation scheduling in the no-wait flowshop with common flow allowance and learning effect

We study the problem of two-machine no-wait flowshop scheduling with learning effect and convex resource-dependent processing times. Under the condition of the due-date assignment with common flow allowance (i.e. slack (SLK) due-date assignment), we provide a bi-criteria analysis where the first criterion is to minimise the scheduling criteria (i.e. the weighted sum of earliness, tardiness and flow allowance costs), and the second criterion is to minimise the resource consumption cost (i.e. the weighted sum of resource consumption cost). The objective is to determine the optimal job sequence, resource allocations and common (flow allowance) slack time that minimise the three different versions of the two criteria. We prove that these problems can be solved in polynomial time.     

A high capacity data centre network: simultaneous 4-PAM data at 20 Gbps and 2 GHz phase modulated RF clock signal over a single VCSEL carrier

Optical fibre communication technologies are playing important roles in data centre networks (DCNs). Techniques for increasing capacity and flexibility for the inter-rack/pod communications in data centres have drawn remarkable attention in recent years. In this work, we propose a low complexity, reliable, alternative technique for increasing DCN capacity and flexibility through multi-signal modulation onto a single mode VCSEL carrier. A 20 Gbps 4-PAM data signal is directly modulated on a single mode 10 GHz bandwidth VCSEL carrier at 1310 nm, therefore, doubling the network bit rate. Carrier spectral efficiency is further maximized by modulating its phase attribute with a 2 GHz reference frequency (RF) clock signal. We, therefore, simultaneously transmit a 20 Gbps 4-PAM data signal and a phase modulated 2 GHz RF signal using a single mode 10 GHz bandwidth VCSEL carrier. It is the first time a single mode 10 GHz bandwidth VCSEL carrier is reported to simultaneously transmit a directly modulated 4-PAM data signal and a phase modulated RF clock signal. A receiver sensitivity of ?10. 52 dBm was attained for a 20 Gbps 4-PAM VCSEL transmission. The 2 GHz phase modulated RF clock signal introduced a power budget penalty of 0.21 dB. Simultaneous distribution of both data and timing signals over shared infrastructure significantly increases the aggregated data rate at different optical network units within the DCN, without expensive optics investment. We further demonstrate on the design of a software-defined digital signal processing assisted receiver to efficiently recover the transmitted signal without employing costly receiver hardware.     

Proposing integrated Shannon’s entropy–inverse data envelopment analysis methods for resource allocation problem under a fuzzy environment

In this study, a two-phase methodology for resource allocation problems under a fuzzy environment is proposed. In the first phase, the imprecise Shannon’s entropy method and the acceptability index are suggested, for the first time in the literature, to select input and output variables to be used in the data envelopment analysis (DEA) application. In the second step, an interval inverse DEA model is executed for resource allocation in a short run. In an effort to exemplify the practicality of the proposed fuzzy model, a real case application has been conducted involving 16 cement firms listed in Borsa Istanbul. The results of the case application indicated that the proposed hybrid model is a viable procedure to handle input–output selection and resource allocation problems under fuzzy conditions. The presented methodology can also lend itself to different applications such as multi-criteria decision-making problems.     

Manipulation and light-induced agglomeration of carbon nanotubes through optical trapping of attached silver nanoparticles

A simple experimental method has been demonstrated for manipulating multi-walled carbon nanotube (MWCNT) bundles through the optical trapping of attached silver nanoparticles (SNPs). In our experiments, without the SNPs, the MWCNTs cannot be trapped due to their irregular shapes and large aspect ratio. However, when mixed with SNPs, the MWCNTs can be successfully trapped along with the SNPs using a TEM(00) mode laser at 532?nm. This is attributed to the optical trapping of the SNPs and attractive interaction or binding between the SNPs and MWCNTs due to electrostatic and van der Waals forces. Therefore, optical manipulation of MWCNT bundles is achieved through the manipulation of the attached silver nanoparticles/aggregates. In addition, we have observed the phenomenon of light-induced further agglomeration of SNPs/MWCNTs which could potentially be exploited for fabricating patterned MWCNT films for future nanoscale devices and other applications.     

Thermo-mechanical probe storage at Mbps single-probe data rates and Tbit in(-2) densities

Future applications for parallel probes, including probe-based data storage and probe lithography, demand that probe technologies achieve patterning rates in the megahertz per probe range at feature sizes below 30?nm, i.e.?～1?Tbit?in(-2). If thermo-mechanical indentation of polymers is employed, some uncertainty remains as to whether the physics governing the indentation kinetics at these short timescales permits the fast indentation processes required. We demonstrate the feasibility of using polymer media for thermo-mechanical probe storage or lithography, at sliding speeds of 15?mm?s(-1) and sub-microsecond indentation times, which fall into this previously untapped regime.     

In situ synthesis of transparent fluorescent ZnS–polymer nanocomposite hybrids through catalytic chain transfer polymerization technique

We report the controllable synthesis of zinc sulfide (ZnS) nanocrystals (NCs)/polymer transparent nanocomposite hybrids in situ based on the catalytic chain transfer polymerization (CCTP) technique. Firstly, a polymeric ligand PMAA [PMAA = poly(acrylic acid)] with controllable low-molecular-weight and a terminal double bond was synthesized through CCTP. Secondly, with the use of this versatile polymeric ligand containing a large number of anchors as the stabilizer, the ZnS NCs were fabricated. Finally, the surface polymeric ligands containing terminal double bonds were copolymerized with methyl methacrylate monomer to form NCs–polymer hybrids through free radical polymerization. The properties of as-prepared ZnS NCs and their nanocomposite hybrids were thoroughly investigated by Fourier transform Raman spectra, Fourier transform infrared spectrum, transmission electron microscope, ultraviolet–visible, photoluminescence, and thermogravimetric analyses measurements. The spectroscopic studies reveal that ZnS–polymer nanocomposite hybrids have good optical properties.     

Low-loss gears precision planetary gearboxes: reduction of the load dependent power losses and efficiency estimation through a hybrid analytical-numerical optimization tool

In the field of robotics, extremely accurate gearboxes are mandatory in order to ensure the adequate precision required by the automatic processes. For these applications, planetary gearboxes represent one of the most attractive solutions because they ensure high reduction ratios in a compact solution.However, their compactness and high power density, imply some thermal limitations.In order to overcome this problem, new gear designs have been studied by a hybrid analytical-numerical approach in order to reduce the power dissipation and, consequently, the operating temperatures.The efficiency increase is obtained mainly by a reduction of the module of the gears. This, together with other modifications of the tooth form (pressure angle, profile shift, etc.), allows to reduce the relative sliding between the tooth flanks that causes the power loss maintaining at the same time an adequate load carrying capacity.Low-loss gears have already been studied by other authors on bigger gears. Furthermore, by means of dedicated CFD simulations performed with an especially developed tool based on the open-source code OpenFOAM®, it has been shown that the sliding optimized design has a positive impact also on the churning power losses. The global winning in terms of reduction of the gear meshing power losses can be assessed in about 50%, depending on the reduction ratio.The new design has been validated by means of experimental tests performed in the internal laboratory of the company. The results have fully validated both the numerical approach and the new design.     

Driver decision-making in the dilemma zone – Examining the influences of clearance intervals,enforcement cameras and the provision of advance warning through a panel data random parameters probit model

In recent years, there have been a series of innovations in the field of vehicle detection at intersection approaches. Modern radar-based smart sensors make it possible to track individual vehicles in close proximity to an intersection. These advancements in technology potentially enable the provision of vehicle- and site-specific decision dilemma zone protection at the onset of the yellow indication at signalized intersections. To exploit this opportunity, it is critical to develop an in-depth understanding of those factors influencing a driver's decision to stop or go at the onset of yellow. This study investigates how signal timing strategies such as yellow interval durations, all-red clearance intervals, advance warning flashers, and automated camera enforcement affect driver decision-making. Data from 87 intersection approaches across five regions of the United States are used to develop a series of decision (i.e., probability of stopping) curves using vehicle trajectory and signal phasing data. A panel data random parameters probit model is used to account for heterogeneity across locations, as well as correlation in driver decision-making, due to unobserved factors that are unique to each signalized intersection. The results demonstrate drivers are more likely to stop at locations where enforcement cameras or flashers are present. Stopping was also more prevalent at intersections with lower speed limits, longer crossing distances, and where pedestrian crosswalks were present.     

Structure and evolution of innovation research in the last 60 years: review and future trends in the field of business through the citations and co-citations analysis

The field of innovation studies has grown considerably in the last four decades, which has led to the emergence of new approaches and theoretical aspects that need to be examined and considered. Therefore, this paper aims to understand what are the main theoretical pillars that support the structure of innovation theories and fields, how it evolved over the years and what are the directions that lead to future trends in innovation research. The procedure consists in a mix-methods using the citation and co-citation analysis associated with bibliometric methods, Social Network Analysis, and a systematic review of the literature. The results were validated by Delphi with academic specialists in innovation. Considering publications between 1956 and 2016 divided into four 15-years timespan, the longitudinal analysis results indicate the evolution of the main streams of thoughts that support the current innovation research fields and depict a research orientation for future works that can be developed to generate relevant contributions for the theoretical development of the area. This paper differentiates itself bringing results based on a large database, by the research methods employed, and by the perspective adopted provides solid contributions to the understanding of the past, present, and future of the scientific research in innovation to business administration field.     

Size- and shape-controlled synthesis of colloidal gold through autoreduction of the auric cation by poly(ethylene oxide)-poly(propylene oxide) block copolymers in aqueous solutions at ambient conditions

Gold nanoparticles with an average diameter in the range 5-20?nm have been synthesized from hydrogen tetrachloroaureate (III) hydrate (HAuCl(4)·3H(2)O) in air-saturated aqueous PEO-PPO-PEO block copolymer solutions at ambient temperature in the absence of any other reducing agent (PEO: poly(ethylene oxide), PPO: poly(propylene oxide)). The particle size was controlled by the block copolymer concentration and PEO and PPO block lengths. Our findings indicate that longer PEO blocks lead to an increase in particle size because of an increase in reaction activity. Adsorption of PO segments on gold nanoparticles seems to prevent particle growth from aggregation, and results in small particle size and high colloidal stability. An increase of the HAuCl(4) concentration causes a change in the particle shape from spherical to triangular or hexagonal nanoplates.