Tool For Tuning Research Articles

Multi-objective optimization based tuning tool for industrial 2doF PID controllers

A computer-aided control system design tool is presented. This tool is able to take advantage of a database of Pareto optimal PID controllers. The idea is to give to the control engineer an useful tool to close the gap between the optimization procedure and the final selection of the parameters. The input to the tool are the allowed degradation of the considered cost functions, the desired level of robustness and the information of the plant, in the form of second order plus time delay model or a set of input-output data. The tool is written as a graphical user interface in MATLAB© and freely available to anyone.

Random multiacceptor poly(2,7‐carbazole) derivatives containing the pentacyclic lactam acceptor unit TPTI for bulk heterojunction solar cells

ABSTRACTHere, a family of donor/acceptor (D/A) alternating copolymers and random two‐acceptor and three‐acceptor copolymers were synthesized via Suzuki polymerization based on heptadecan‐9‐yl substituted carbazole as a donor and 4,7‐Bis(5‐bromothiophene‐2‐yl)benzo[c][1,2,5]thiadiazole (DTBT), 2,5‐diethylhexyl‐3,6‐bis(5‐bromothiophene‐2‐yl)pyrrolo[3,4‐c]‐pyrrole‐1,4‐dione (DPP) and 2,8‐dibromo‐4,10‐bis(2‐ethylhexyl)thieno[2′,3′:5,6] pyrido[3,4‐g]thieno[3,2‐c]isoquinoline‐5,11(4H,10H)‐dione (TPTI) as acceptors. For the first time, a relatively new electron‐deficient TPTI unit was used as an acceptor in carbazole‐based conjugated polymers. Introduction of the electron‐deficient TPTI unit into the polymer backbone increased the open‐circuit voltage (Voc) of the resulting polymer solar cells up to 0.96 V. PCTPTI and PCDTBT‐TPTI exhibited external quantum efficiencies (EQE) up to 75%. All random two‐acceptor copolymers showed broadened absorption profiles compared to the D/A alternating analogues. In order to further improve the light absorption, a random three‐acceptor copolymer was synthesized for the first time, resulting in the broadest absorption in the range of 350–750 nm. Highest occupied molecular orbital (HOMO) energies and Voc values of the resulting polymers could be successfully tuned by introducing different monomer units into the polymer backbone in different ratios. These results indicate that TPTI is a promising acceptor unit for conjugated polymers and that the random copolymer approach is a successful tool for fine tuning of polymer properties. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 2781–2786

Chemical and Photochemical Water Oxidation by [RuCl(NCNHCO)(DMSO)(py)]‐Type Complexes

AbstractIn this work, the effects of substitutions in the backbone of imidazolylidene and axial ligands on the reactivity and stability of water‐oxidation catalysts were investigated. Three pincer‐type asymmetric imidazolium salts NCNHCO, NCNHC‐4BrO, and NCNHC‐BO (NHC: N‐heterocyclic carbene), of which the donating ability of the corresponding imidazolylidene decreases in the same sequence, were prepared. Their application in metalation afforded the corresponding Ru complexes 1 a, 1 b, 2, and 3. It was found that the complexes incorporating the stronger donor displayed lower potential for each redox couple and longer lifetimes, but relatively low reaction rates. Under acidic conditions, water oxidation driven by cerium ammonium nitrate resulted in turnover numbers (TONs) of 2322, 1728, 1928, and 2208 for 1 a, 1 b, 2, and 3, respectively. Complex 2 exhibited a good match of reactivity and stability with a TON of 136 in a typical three‐component photocatalysis. Importantly, NHCs could be another powerful tool for tuning the reactivity and stability of water‐oxidation catalysts, in addition to substituted pyridines. Rational orchestration of modified NHCs and pyridines could eventually result in water‐oxidation catalysts exhibiting appreciable effectiveness and considerable robustness.

An emerging integration between ionic liquids and nanotechnology: general uses and future prospects in drug delivery.

There is a growing need to develop drug-delivery systems that overcome drawbacks such as poor drug solubility/loading/release, systemic side effects and limited stability. Ionic liquids (ILs) offer many advantages and their tailoring represents a valuable tuning tool. Nano-based systems are also prized materials that prevent drug degradation, enhance their transport/distribution and extend their release. Consequently, structures containing ILs and nanoparticles (NPs) have been developed to attain synergistic effects. This overview on the properties of ILs, NPs and of their combined structures, reveals the recent advances in these areas through a review of pertinent literature. The IL-NP structures present enhanced properties and the subsequent performance upgrade proves to be useful in drug delivery, although much is yet to be done.

User interface-level QoE analysis for Android application tuning

For the tuning and optimization of mobile applications, user Quality of Experience (QoE) should be closely considered as a key development metric. While previous research has approached application tuning from different perspectives, there has rarely been any sophisticated analysis of QoE at the user interface level. In this paper, we propose QX-probe, a comparative and quantitative QoE analysis tool for application tuning. We define latency, energy, and UI (User Interface) usage information as critical factors for QoE analysis. QX-probe measures these factors at the UI level and provides a range of information for QoE analysis by means of a web-based tool. The usefulness of QX-probe is validated through a number of case studies using real application. Developers should be able to use this tool to identify application tuning points.

Co-doping as a tool for tuning the optical properties of singlewalled carbon nanotubes: A first principles study

This paper presents a first principles study on the effect of co-doping on various optical spectra of a zigzag single-walled carbon nanotube (SWCNT). Optical spectra of a pristine SWCNT, SWCNT co-doped with Aluminum (Al) & Phosphorus (P) and another one co-doped with Al, P and Nitrogen (N) have been calculated using density functional theory (DFT).The theory has been implemented using the Cambridge sequential total energy package (CASTEP) code available as a userfriendly module with the software ‘Material Studio’. Polarized and unpolarized light as well as light through polycrystalline media have been considered. The dependence of various spectra on the status of incident light presents a clear evidence of anisotropicity in the optical properties. Analysis of the simulated spectra involves calculation and comparison of different optical properties like dielectric function, reflectivity, refractive index, conductivity and loss function for the pristine and co-doped SWCNTs. Noticeable variations are observed in the optical properties on simultaneously doping the SWCNT with Al and P and then further introducing N atom into the structure so that it can be concluded that co-doping (simultaneous doping with different combinations of dopants) can be evolved as a novel and effective tool for tailoring the optical properties of SWCNTs as per the requirements while designing an optical device. It will prove to be highly significant for effective designing of SWCNT based sensitive optical devices for a variety of technological applications.

Adsorption of dihalogen molecules on pristine graphene surface: Monte Carlo and molecular dynamics simulation studies.

Weak interactions of graphene surface with reactive molecular impurities are the subject of many studies since noncovalent functionalization of surface via molecular doping is a powerful tool for tuning the electronic properties of graphene layers. In this work, the adsorption of diatomic halogen gas molecules, F2, Cl2, Br2, I2 onto bilayer and multilayer pristine graphene surfaces were studied comparatively by Monte Carlo (MC) and molecular dynamics (MD) simulation techniques in canonical ensemble. The adsorption sites, adsorption capacity, coverage factors, adsorption isotherms, and adsorption kinetics were investigated and the adsorption energies were calculated for all adsorbates. Graphene was modeled as a two-dimensional layer of 200 carbon atoms in a honeycomb arrangement. The COMPASS force field was used in the simulations. The adsorption isotherms were obtained and fitted to Langmuir model. The kinetics of adsorption was studied and found to be first order. Both the monolayer and the multilayer adsorption of halogen molecules showed that van der Waals volumes of halogen molecules and also their polarizabilities display a competitive role in the saturation capacity and the strength of surface interactions.

HeDPM: load balancing of linear pipeline applications on heterogeneous systems

This work presents a new algorithm, called Heterogeneous Dynamic Pipeline Mapping, that allows for dynamically improving the performance of pipeline applications running on heterogeneous systems. It is aimed at balancing the application load by determining the best replication (of slow stages) and gathering (of fast stages) combination taking into account processors computation and communication capacities. In addition, the algorithm has been designed with the requirement of keeping complexity low to allow its usage in a dynamic tuning tool. For this reason, it uses an analytical performance model of pipeline applications that addresses hardware heterogeneity and which depends on parameters that can be known in advance or measured at run-time. A wide experimentation is presented, including the comparison with the optimal brute force algorithm, a general comparison with the Binary Search Closest algorithm, and an application example with the Ferret pipeline included in the PARSEC benchmark suite. Results, matching those of the best existing algorithms, show significant performance improvements with lower complexity (O(N^3), where N is the number of pipeline stages).

Too Hot for Photon-Assisted Transport: Hot-Electrons Dominate Conductance Enhancement in Illuminated Single-Molecule Junctions.

We investigate light-induced conductance enhancement in single-molecule junctions via photon-assisted transport and hot-electron transport. Using 4,4'-bipyridine bound to Au electrodes as a prototypical single-molecule junction, we report a 20-40% enhancement in conductance under illumination with 980 nm wavelength radiation. We probe the effects of subtle changes in the transmission function on light-enhanced current and show that discrete variations in the binding geometry result in a 10% change in enhancement. Importantly, we prove theoretically that the steady-state behavior of photon-assisted transport and hot-electron transport is identical but that hot-electron transport is the dominant mechanism for optically induced conductance enhancement in single-molecule junctions when the wavelength used is absorbed by the electrodes and the hot-electron relaxation time is long. We confirm this experimentally by performing polarization-dependent conductance measurements of illuminated 4,4'-bipyridine junctions. Finally, we perform lock-in type measurements of optical current and conclude that currents due to laser-induced thermal expansion mask optical currents. This work provides a robust experimental framework for studying mechanisms of light-enhanced transport in single-molecule junctions and offers tools for tuning the performance of organic optoelectronic devices by analyzing detailed transport properties of the molecules involved.

Surface Functionalization and Electrical Discharge Sensitivity of Passivated Al Nanoparticles.

Passivated aluminum nanoparticles are surface functionalized to elucidate their sensitivity against an electrical discharge. Two size fractions that differ in surface morphology are investigated. Electronic interactions between the partly inert, partly energetic organic molecules used for surface functionalization and the alumina surface are analyzed in detail. The nanoparticle surfaces are modified with the well-established, inert 2-[2-(2-methoxyethoxy)ethoxy]acetic acid, whereas energetic surface modification is achieved using 1,3,5-trinitroperhydro-1,3,5-triazine or the acidic and aromatic 2,4,6-trinitrophenol. A mechanistic model for the chemical surface functionalization of Al nanoparticles is hypothesized and corroborated by comprehensive optical and Fourier transform infrared spectroscopy studies. The surface structures are adjusted by developing a tunable stabilization procedure that prevents sedimentation and hence increases the saturation concentration in the liquid phase and finally affects the sensitivity character in view of electrical discharge ignition of dry powders. Detailed material characterization is conducted using transmission electron microscopy, combined with energy-dispersive X-ray spectroscopy and various absorption spectroscopy techniques (steady state in the infrared and ultraviolet/visible regime). The adjustment of surface structures of the distinct Al nanoparticle samples offers a valuable tool for tuning and tailoring the reactivity, sensitivity, stability, and energetic performances of the nanoparticles, and thereby enables the safe use of these multipurpose nanoparticles.

Vibrational energy harvesting by exploring structural benefits and nonlinear characteristics

Traditional energy harvesters are often of low efficiency due to very limited energy harvesting bandwidth, which should also be enough close to the ambient excitation frequency. To overcome this difficulty, some attempts can be seen in the literature typically with the purposes of either increasing the energy harvesting bandwidth with a harvester array, or enhancing the energy harvesting bandwidth and peak with nonlinear coupling effect etc. This paper presents an alternative way which can achieve tuneable resonant frequency (from high frequency to ultralow frequency) and improved energy harvesting bandwidth and peak simultaneously by employing special structural benefits and advantageous displacement-dependent nonlinear damping property. The proposed energy harvesting system employs a lever systems combined with an X-shape supporting structure and demonstrates very adjustable stiffness and unique nonlinear damping characteristics which are very beneficial for energy harvesting. It is shown that the energy harvesting performance of the proposed system is directly determined by several easy-to-tune structural parameters and also by the relative displacement in a special nonlinear manner, which provides a great flexibility and/or a unique tool for tuning and improving energy harvesting efficiency via matching excitation frequencies and covering a broader frequency band. This study potentially provides a new insight into the design of energy harvesting systems by employing structural benefits and geometrical nonlinearities.

Substituent-sensitive fluorescence of sequentially N-alkylated tetrabenzotetraaza[8]circulenes

We explore the use of substituent-sensitive balance between fluorescence and non-radiative decay as a tool for optical tuning of N-butylated tetrabenzotetraaza[8]circulenes for organic light emitting diode applications.

Design of Synthetic Promoters for Gene Circuits in Mammalian Cells.

Synthetic biology, the synthesis of engineering and biology, has rapidly matured and has dramatically increased the complexity of artificial gene circuits in recent years. The deployment of intricate synthetic gene circuits in mammalian cells requires the establishment of very precise and orthogonal control of transgene expression. In this chapter, we describe methods of modulating the expression of transgenes at the transcriptional level. Using cAMP-response element-binding protein (CREB)-dependent promoters as examples, a tool for the precise tuning of gene expression by using different core promoters and by varying the binding affinity of transcription factor operator sites is described.

Analysis of sensor middleware using big data as a cloud computing utility

This paper aims at implementing an efficient sensor middleware for maintaining and managing big data and analysing the efficiency of such a sensor middleware. The work focused on designing of sensor middleware and performance analysis of the sensor middleware. The Hadoop framework, which was used as a sensor middleware, was responsible for maintaining and managing the distributed sensor environment. A prominent monitoring tool such as Zabbix was used to monitor the Hadoop processes and provide alerts for custom trigger events. Performance analysis for the sensor middleware such as Hadoop was done using tools such as collectl and colplot. Performance analysis of Hadoop cluster was performed using an evaluation metric such as total runtime of the job. A brief discussion on the Hadoop tuning tool such as starfish, that makes the Hadoop cluster efficient through configuration changes, is also presented.

XDEM for Tuning Lumped Models of Thermochemical Processes Involving Materials in the Powder State

Processes involving materials in gaseous and powder states cannot be modelled without coupling interactions between the two states. XDEM (Extended Discrete Element Method) is a valid tool for tackling this issue, since it allows a coupled CFD-DEM simulation to be run. Such strength, however, mainly finds in long computational times its main drawback. This aspect is indeed critical in several applications, since a long computational time is in contrast with the increasing demand for predictive tools that can provide fast and accurate results in order to be used in new monitoring and control strategies. This paper focuses on the use of the XDEM framework as a tool for fine tuning a lumped representation of the non-isothermal decarbonation of a CaCO3 sample in powder state. The tuning of the lumped model is performed exploiting the multi-objective optimization capability of genetic algorithms. Results demonstrate that such approach makes it possible to estimate fast and accurate models to be used, for instance, in the fields of virtual sensing and predictive control.

Tuning of Silver Catalyst Mesostructure Promotes Selective Carbon Dioxide Conversion into Fuels.

An electrode's performance for catalytic CO2 conversion to fuels is a complex convolution of surface structure and transport effects. Using well-defined mesostructured silver inverse opal (Ag-IO) electrodes, it is demonstrated that mesostructure-induced transport limitations alone serve to increase the turnover frequency for CO2 activation per unit area, while simultaneously improving reaction selectivity. The specific activity for catalyzed CO evolution systematically rises by three-fold and the specific activity for catalyzed H2 evolution systematically declines by ten-fold with increasing mesostructural roughness of Ag-IOs. By exploiting the compounding influence of both of these effects, we demonstrate that mesostructure, rather than surface structure, can be used to tune CO evolution selectivity from less than 5 % to more than 80 %. These results establish electrode mesostructuring as a powerful complementary tool for tuning both catalyst selectivity and efficiency for CO2 conversion into fuels.

Tuning of Silver Catalyst Mesostructure Promotes Selective Carbon Dioxide Conversion into Fuels

AbstractAn electrode's performance for catalytic CO2 conversion to fuels is a complex convolution of surface structure and transport effects. Using well‐defined mesostructured silver inverse opal (Ag‐IO) electrodes, it is demonstrated that mesostructure‐induced transport limitations alone serve to increase the turnover frequency for CO2 activation per unit area, while simultaneously improving reaction selectivity. The specific activity for catalyzed CO evolution systematically rises by three‐fold and the specific activity for catalyzed H2 evolution systematically declines by ten‐fold with increasing mesostructural roughness of Ag‐IOs. By exploiting the compounding influence of both of these effects, we demonstrate that mesostructure, rather than surface structure, can be used to tune CO evolution selectivity from less than 5 % to more than 80 %. These results establish electrode mesostructuring as a powerful complementary tool for tuning both catalyst selectivity and efficiency for CO2 conversion into fuels.

Superior color rendering with a phosphor‐converted blue‐cyan monolithic light‐emitting diode

AbstractThe future generation of modern illumination should not only be cheap and highly efficient, but also demonstrate high quality of light, light which allows better color differentiation and fidelity. Here we are presenting a novel approach to create a white solid‐state light source providing ultimate color rendition necessary for a number of applications. The proposed semi‐hybrid device combines a monolithic blue‐cyan light emitting diode (MBC LED) with a green‐red phosphor mixture. It has shown a superior color rendering index (CRI), 98.6, at correlated color temperature of around 3400 K. The MBC LED epi‐structure did not suffer from the efficiency reduction typical for monolithic multi‐color emitters and was implemented in the two most popular chip designs: “epi‐up” and “flip‐chip”. Redistribution of the blue and cyan band amplitudes in the white‐light emission spectrum, using the operating current, is found to be an effective tool for fine tuning the color characteristics. image

Red-emitting CO2 sensors with tunable dynamic range based on pH-sensitive azaphthalocyanine indicators

A new group of optical CO2 sensors based on red-emitting pH-sensitive zinc azaphthalocyanine (Zn-AzaPc) indicators embedded into polyurethane polymeric matrices is presented. The effects of particular Zn-AzaPc indicator, type of a polymeric matrix and a base on sensing properties are investigated. All the indicators are virtually non-fluorescent in the deprotonated form (in the absence of CO2) and are “switched on” in presence of the analyte. Zn-AzaPc without any phenolate moiety is used as a positive control (always-ON state). Among the indicators with one, two and four phenolate receptors, the dye with one receptor is the most suitable due to brightest emission in ON state. Sufficient water content is found to be particularly important in case of the hydrophobic Zn-AzaPc indicators and leads to the necessity of employing hydrophilic HydroThane™ matrices instead of conventional ethylcellulose matrix. Among them HydroThane™ 25 showed the most promising results with the highest increase in fluorescence intensity between OFF/ON states (12×), reasonably high fluorescence quantum yields in ON state (0.071) and the most reliable and reproducible response to CO2 in sensing range 0–95kPa pCO2 with the limited temperature-dependency in the range 15–35°C. Importantly, sensitivity significantly increased with shortening of the alkyl chains of a base, i.e. in order TOAOH< TBAOH<TEAOH that gives us a nice tool for tuning the dynamic range of CO2 sensors for different applications. Finally, fiber-optic sensors compatible with a commercially available compact phase fluorometer as well as materials for 2-wavelength sensing and imaging are prepared and possibility of a referenced read-out is demonstrated.

Optimizing Blue Persistent Luminescence in (Sr1-δBaδ)2MgSi2O7:Eu2+,Dy3+ via Solid Solution for Use in Point-of-Care Diagnostics.

Inorganic persistent luminescent phosphors are an excellent class of optical reporters for enabling sensitive point-of-care diagnostics, particularly with smartphone-based biosensing devices in testing formats such as the lateral flow assay (LFA). Here, the development of persistent phosphors for this application is focused on the solid solution (Sr1-δBaδ)2MgSi2O7:Eu2+,Dy3+ (δ = 0, 0.125, 0.25, 0.375), which is prepared using a high-temperature solid-state reaction as confirmed by synchrotron X-ray powder diffraction. The substitution of barium for strontium enables control over the Eu2+ 5d-orbital crystal field splitting (CFS) as a tool for tuning the emission wavelength while maintaining luminescence lifetimes >9 min across the composition range. Thermoluminescence measurements of the solid solution provide evidence that trap states contribute to the persistent lifetimes with the trap depths also remaining constant as a function of composition. Time-gated luminescence images of these compounds are captured on a smartphone arranged in a layout to mimic a point-of-care test and demonstrate the viability of using these materials as optical reporters. Moreover, comparing the blue-emitting (Sr0.625Ba0.375)2MgSi2O7:Eu2+,Dy3+ and the green-emitting SrAl2O4:Eu2+,Dy3+ in a single LFA-type format shows these two compounds can be detected and resolved simultaneously, thereby permitting the development of a multiplexed LFA.