Final Assemblies Research Articles

Performance Evaluation of an Engine Assembly Line through Simulation

Simulation can be used in industrial field allowing the systems behavior to be learnt and tested. This work involves simulation and analysis of the engine assembly line. An engine assembly line contains three subsystems namely engine assembly, hot test line and paint shop. A simulation model built up in modeling software-WITNESS by considered entire set of data. The model validated and several what-if scenarios generated. The different scenario has been analyzed. Finally the throughput, optimum number of pallet and bottleneck identified. This paper discusses the need and uses of discrete event simulation in the design for final engine assemblies.

A selective assembly strategy to improve the components’ utilization rate with an application to hard disk drives

In this paper, we focus on ways to optimize the manufacturing of products whereby the final product performance is measured by the aggregated performances of its components. Specifically for hard disk drives, the final recording capacity is the aggregate of the components’ achievable capacities. As is the case for hard disk drive, a drive normally has a targeted capacity such that if it falls below its target, it will be rejected or downgraded. Similarly, products achieving well above the target will still be sold at the target capacity. At both extremes, it results in loss of profits. Hence, the aim of this paper is to propose a novel selective assembly strategy which can improve profitability by reducing the variation of components in the final product assemblies and achieving the target performance. As our case study, the assembly of hard disk drive (HDD) is used to demonstrate its feasibility in real manufacturing settings. Two theorems, (1) discarding theorem and (2) binning theorem, are formulated to guide the selective assembly strategy. They provide the rules for discarding inferior components before assembly to ensure the quality of the starting population and the rules for selecting matching pairs of components to prevent producing over qualified product. The improvement in component utilization rate over random binning is guaranteed by the two theorems.

Spontaneous Stepwise Self‐Assembly of a Polyoxometalate–Organic Hybrid into Catalytically Active One‐Dimensional Anisotropic Structures

An inorganic-organic hybrid surfactant with a hexavanadate cluster as the polar head group was designed and observed to assemble into micelle structures, which further spontaneously coagulate into a 1D anisotropic structure in aqueous solutions. Such a hierarchical self-assembly process is driven by the cooperation of varied noncovalent interactions, including hydrophobic, electrostatic, and hydrogen-bonding interactions. The hydrophobic interaction drives the quick formation of the micelle structure; electrostatic interactions involving counterions leads to the further coagulation of the micelles into larger assemblies. This process is similar to the crystallization process, but the specific counterions and the directional hydrogen bonding lead to the 1D growth of the final assemblies. Since most of the hexavanadates are exposed to the surface, the 1D assembly with nanoscale thickness is a highly efficient heterogeneous catalyst for the oxidation of organic sulfides with appreciable recyclability.

Self-assembly of pyridinium-functionalized anthracenes: molecular-skeleton-directed formation of microsheets and microtubes.

Two amphiphilic regioisomers, 9-AP (1-[11-(9-anthracenylmethoxy)-11-oxoundecyl]pyridinium bromide), and 2-AP (1-[11-(2-anthracenyl methoxy)-11-oxoundecyl]pyridinium bromide), were synthesized and their assembly behaviors were studied. Due to the anisotropic features of the anthracene structure, different substituted positions on the anthracene ring lead 9-AP and 2-AP to adapt "shaver" and "spatula"-like molecular shapes, respectively, which consequently dictate the structure of their final assemblies. While "shaver"-shaped 9-AP assembled into microsheets, driven by π-π interactions, "spatula"-shaped 2-AP assembled into microtubular structures, promoted primarily by charge-transfer interactions.

Finishing bacterial genome assemblies with Mix

MotivationAmong challenges that hamper reaping the benefits of genome assembly are both unfinished assemblies and the ensuing experimental costs. First, numerous software solutions for genome de novo assembly are available, each having its advantages and drawbacks, without clear guidelines as to how to choose among them. Second, these solutions produce draft assemblies that often require a resource intensive finishing phase.MethodsIn this paper we address these two aspects by developing Mix , a tool that mixes two or more draft assemblies, without relying on a reference genome and having the goal to reduce contig fragmentation and thus speed-up genome finishing. The proposed algorithm builds an extension graph where vertices represent extremities of contigs and edges represent existing alignments between these extremities. These alignment edges are used for contig extension. The resulting output assembly corresponds to a set of paths in the extension graph that maximizes the cumulative contig length.ResultsWe evaluate the performance of Mix on bacterial NGS data from the GAGE-B study and apply it to newly sequenced Mycoplasma genomes. Resulting final assemblies demonstrate a significant improvement in the overall assembly quality. In particular, Mix is consistent by providing better overall quality results even when the choice is guided solely by standard assembly statistics, as is the case for de novo projects.AvailabilityMix is implemented in Python and is available at https://github.com/cbib/MIX, novel data for our Mycoplasma study is available at http://services.cbib.u-bordeaux2.fr/mix/.

General Structure Layout and Design of Target Area of SGIII Facility

ShenGuang III (SGIII) facility will be constructed for research in Inertial Confinement Fusion. In this paper, general structure layout and design of target area of SGIII facility are described. Target area structure support system must provide a stable and precisely platform for optical elements before and during a shot. General structure layout must satisfy the mul-function consideration and logistic priority. The modularity and hardware commonality, cleanliness, and low neutron activation should be considered in the structural design of target area. The general structure layout of target area is rectangle. The target bay and the switchyard have the multi-layered layout to satisfy the demand of transporting beam lasers unidirectionally from south to north and supporting the optics modules and physical diagnostic instruments with different height. The passageways of population & goods flow of target area are designed to include the vertical channels between the different layers and the horizontal channels on the same layer. The opto-mechanical elements (OM) are classified as OM1, OM2, and OM3. The OM1 are the infrastructures. The OM2 include target chamber, the shell of final optics assemblies, the mirror frames, and the beam enclosures. The OM3 is line replaceable units that are attached to the OM2 on kinematic equivalent three-vee mounts.

Design of Transport Beams Arrangement in Target Area of SG-III Facility

In target area of Inertial Confinement Fusion (ICF) facility, the rectangular beams arrangement at the main amplifier (MA) output is mapped to the spherical-geometry beams configuration near the target chamber. The beams are imported into the final optical assemblies with special angles. In this paper, the transport beams arrangement design of SG-III facility is described. Firstly, the primary requirements of the transport beams arrangement in ICF target area system are given. Then the typical transport beam pathway from the MA output to the target chamber center is analyzed. The general layout, beams path length, and the parameters of transport mirrors are discussed for the transport beam arrangement.

Book Review: A Nineteenth-Century Clockmaker, Heinrich Johann Kessels (1781–1849): Ein bedeutender Verfertiger von Chronometern und Präzisionspendeluhren

A NINETEENTH-CENTURY CLOCKMAKER Heinrich Johann Kessels (1781-1849): Ein bedeutender Verfertiger von Chronometern und Prazisionspendeluhren. Gunther Oestmann (Acta Historica Astronomiae, xliv; Verlag Harri Deutsch, Frankfurt aM, 2011). Pp. 271. euro24.80. ISBN 978-3-8171-1884-7.Volume xliv of the Acta Historica Astronomiae is dedicated to the life and work of the clockmaker Heinrich Johann Kessels. Gunther Oestmann, author of this work, is a clockmaker and historian of science, whose researches in the field of history of horology, navigation, astronomy, scientific instruments and mathematical geography are well known.The volume is divided into three sections. The first deals with the life and professional achievement of Kessels. He was born in Maastricht, but very little is known of his early years. Certainly he spent some time in England where he learned the art of clock making, working in some of the most renowned workshops of the time. Unfortunately we do not know who his masters were; but he clearly developed a very high level of skill that allowed him to undertake several important works when in 1815 he moved to Paris and entered the shop of the renowned maker, Abraham Louis Breguet. In Paris, Kessels worked on the most sophisticated mechanical timekeepers then being produced, such as marine and pocket chronometers, tourbillons, and highly sophisticated clocks. There he became a highly qualified clockmaker.In Paris Kessels met the German astronomer and geodesist Heinrich Christian Schumacher, one of Breguet's clients. Their relationship played a fundamental role in Kessels's decision to move to northern Germany, first to Hamburg and in 1823 in the nearby Altona, where Schumacher had installed his own astronomical observatory. Kessels established his own workshop there, married in 1829, and became Danish citizen. The time and the conditions for founding a precision clock-making workshop were favourable. In the first half of the nineteenth century, several important astronomical and naval observatories would be founded. Many amateur astronomers were equipping their own private observatories. At the same time, important governmental geodetic surveys were undertaken and the navy as well as the commercial navigation in Denmark and in Northern Germany were fast developing. Altona and Hamburg quickly became important ports. All these activities required an increasing number of scientific instruments, especially box chronometers and astronomical regulators (clocks). Such time-keeping apparatus had to be periodically adjusted. And the Danish King Frederik IV was highly interested in astronomy and related sciences. Schumacher, who had an excellent relationship with the king and the government, could thus facilitate the development of Kessels's business and support his career.Unfortunately, information about Kessels's workshop is scarce. Presumably he had several employees. As general manager of his firm, he supervised the different types of work, personally made or completed the most delicate parts and arranged the final assemblies and tests. …

Catalyst Coated PBI Membrane High Temperature Assemblies

A route has been developed to stabilise a polybenzimidazole gel membrane formed in polyphosphoric acid by simultaneous cross-linking. With increasing degrees of cross-linking the mechanical properties of the high acid content PBI membranes are significantly improved, while the phosphoric acid content and the membrane conductivity are not greatly affected. PBI/H3PO4 membranes are generally integrated into an assembly using gas diffusion electrodes. In the present work, cross-linked PBI membranes have been used as substrates for catalyst coated membrane preparation using a Pt/C catalyst transferred by decal to the membrane surfaces. The final membrane electrode assemblies have been characterized for their high temperature performance and durability.

Target area structural design of ShenGuangIII

This paper will present a summary of the target area structural design results of ShenGuangIII (SGIII), which includes target bay and switchyard support structures, target chamber, and beam transport system. The target area building is rectangular and includes a target bay and a switchyard. The outer wall of the target area building is based outside the vibration isolation trenches and separates the diurnal temperature loads and the wind loads that occur outside the target area building during the alignment process prior to a shot. The target bay and switchyard support structures are mainly comprised of the steel reinforced concrete building and the steel space frame. The target chamber is a welded sphere made of aluminum alloy 5052 and has an inner diameter of 6m and a nominal wall thickness of 8cm. The beam transport system brought the 48 laser beams to the final optics assemblies (FOAs) and includes 276 transport mirrors. Sources that influence stability are mainly ambient random vibration, ambient wind induced vibrations, diurnal temperature changes, and HVAC. A FEM is used to calculate the responses of the target area structure under broadband ambient random vibration. The position deviations of 48 beam lines are calculated and used to evaluate the stability of the target area structure. The analyses demonstrated that the positioning deviations of 48 beam lines satisfy the deviation budget requirements.

How does sequence variability affect de novo assembly quality?

Molecular genetic tools have become standard in biological studies of both model and non-model species. This has created a growing need for sequence information, a resource hitherto limited for many species. With new sequencing technologies this is rapidly changing, and whole genome shotgun sequencing has become a realistic goal for many species. However, present sequencing protocols require more DNA than can be extracted from single individuals of many small metazoans, potentially forcing sequencing projects to perform sequencing on samples derived from several individuals. A pertinent question thus arises: can wild samples be used or is inbreeding necessary? In the present study we compare assemblies generated using sequence data from inbred and wild Lepeophtheirus salmonis. The results indicate not only that measures to reduce the genetic variability may significantly improve the final assemblies but also that deeper coverage to some extent can compensate for the detrimental effects of natural sequence variability.

Programming Hierarchical Supramolecular Nanostructures by Molecular Design

Supramolecular nanostructures with tunable dimensionalities are fabricated by deposition of benzene–carboxylic acids on the Cu(110) surface. By tailoring the number and position of the functional moieties, the structure of the final molecular assemblies can be rationally modified ranging from isolated one-dimensional chains to compact two-dimensional islands. Molecular units are chosen that can assemble through metal–organic and electrostatic interactions. The hierarchy between these intermolecular forces guarantees that a primary organization level, constituted by metal–organic polymeric chains, is developed by all molecular units while the secondary interchain interactions can be arbitrarily adjusted. Scanning tunneling microscopy, density functional theory calculations, and kinetic Monte Carlo simulations are used to characterize and rationalize the experimental findings.

Lens centering of aspheres for high-quality optics

Abstract The assembly effort of optical systems can be reduced immensely by the use of appropriate manufacturing technologies. For refractive optical systems with a common axis of symmetry, lens centering allows a final system assembly with high accuracy and minimal effort, but is today mostly limited to spherical optical elements only. To overcome the current restrictions, a lens centering process for one-sided aspherical lenses was investigated both in theory and practice. The deviation of the rotational aspheric axis from a reference spindle axis is measured precisely with an electronic autocollimator and an additional distance sensor at the same time. Displacements can be minimized by a combination of lateral and rotational alignment motions, aiming at a coaxiality of both axes. In order to achieve a high performance of the entire optical system, the centered lens housings are machined with a diamond tool at their outer diameter, ground, and top surfaces. The feasibility of the complete process was proved by machining several aspherical lenses and measuring the final assemblies with a coordinate measuring machine. Thereby, a residual decenter <1 μm for the aspheric vertex and a tilt <0.5 arcmin between the aspheric axis and the axis of symmetry of the lens housing could be verified. The achievable manufacturing tolerances prove the practicability of the proposed lens-centering process for a majority of high-quality optical applications.

Thermal cycling analysis of high temperature die-attach materials

This work aims at the experimental thermo-mechanical evaluation of different die-attach materials using test vehicles representing the final packaging assemblies. The experiments are based on a harsh thermal cycling system and analysis tools for evaluating the final die-attach integrity. In this paper, we present a finite elements simulation analysis of the test vehicle, the design of the harsh thermal cycling system (−80 to 400°C) and the first results obtained with AuGe and PbSnAg as die-attach alloys.

De novo assembly of highly diverse viral populations

BackgroundExtensive genetic diversity in viral populations within infected hosts and the divergence of variants from existing reference genomes impede the analysis of deep viral sequencing data. A de novo population consensus assembly is valuable both as a single linear representation of the population and as a backbone on which intra-host variants can be accurately mapped. The availability of consensus assemblies and robustly mapped variants are crucial to the genetic study of viral disease progression, transmission dynamics, and viral evolution. Existing de novo assembly techniques fail to robustly assemble ultra-deep sequence data from genetically heterogeneous populations such as viruses into full-length genomes due to the presence of extensive genetic variability, contaminants, and variable sequence coverage.ResultsWe present VICUNA, a de novo assembly algorithm suitable for generating consensus assemblies from genetically heterogeneous populations. We demonstrate its effectiveness on Dengue, Human Immunodeficiency and West Nile viral populations, representing a range of intra-host diversity. Compared to state-of-the-art assemblers designed for haploid or diploid systems, VICUNA recovers full-length consensus and captures insertion/deletion polymorphisms in diverse samples. Final assemblies maintain a high base calling accuracy. VICUNA program is publicly available at: http://www.broadinstitute.org/scientific-community/science/projects/viral-genomics/ viral-genomics-analysis-software.ConclusionsWe developed VICUNA, a publicly available software tool, that enables consensus assembly of ultra-deep sequence derived from diverse viral populations. While VICUNA was developed for the analysis of viral populations, its application to other heterogeneous sequence data sets such as metagenomic or tumor cell population samples may prove beneficial in these fields of research.

Transcriptome-based exon capture enables highly cost-effective comparative genomic data collection at moderate evolutionary scales

BackgroundTo date, exon capture has largely been restricted to species with fully sequenced genomes, which has precluded its application to lineages that lack high quality genomic resources. We developed a novel strategy for designing array-based exon capture in chipmunks (Tamias) based on de novo transcriptome assemblies. We evaluated the performance of our approach across specimens from four chipmunk species.ResultsWe selectively targeted 11,975 exons (~4 Mb) on custom capture arrays, and enriched over 99% of the targets in all libraries. The percentage of aligned reads was highly consistent (24.4-29.1%) across all specimens, including in multiplexing up to 20 barcoded individuals on a single array. Base coverage among specimens and within targets in each species library was uniform, and the performance of targets among independent exon captures was highly reproducible. There was no decrease in coverage among chipmunk species, which showed up to 1.5% sequence divergence in coding regions. We did observe a decline in capture performance of a subset of targets designed from a much more divergent ground squirrel genome (30 My), however, over 90% of the targets were also recovered. Final assemblies yielded over ten thousand orthologous loci (~3.6 Mb) with thousands of fixed and polymorphic SNPs among species identified.ConclusionsOur study demonstrates the potential of a transcriptome-enabled, multiplexed, exon capture method to create thousands of informative markers for population genomic and phylogenetic studies in non-model species across the tree of life.

Antibonding Plasmon Modes in Colloidal Gold Nanorod Clusters

The optical response of nanoplasmonic colloids in disperse phase is strictly related to their shape. However, upon self-assembly, new optical features, for example, bonding or antibonding modes, emerge as a result of the mutual orientations of nanoparticles. The geometry of the final assemblies often determines which mode is dominating in the overall optical response. These new plasmon modes, however, are mostly observed in silico, as self-assembly in the liquid phase leads to cluster formation with a broad range of particle units. Here we show that low-symmetry clustering of gold nanorods (AuNRs) in solution can also reveal antibonding modes. We found that UV-light irradiation of colloidal dispersions of AuNRs in N-methyl-2-pyrrolidone (NMP), stabilized by poly(vinylpyrrolidone) (PVP) results in the creation of AuNRs clusters with ladderlike morphology, where antibonding modes can be identified. We propose that UV irradiation induces formation of radicals in solvent molecules, which then promote cross-linking of PVP chains on the surface of adjacent particles. This picture opens up a number of relevant questions in nanoscience and is expected to find application in light induced self-assembly of particles with various compositions and morphologies.

Solid state deposition of chiral amphiphilic porphyrin derivatives on glass surface

Herein, we present a straightforward method to achieve optically active films based on porphyrin derivatives. The introduction of an aminoacid functionality on the porphyrin platform confers to the macrocycle both the amphiphilic and chiral character exploited for its solvent-promoted self-aggregation leading to the formation of chiral supramolecular architectures. These ordered suprastructures have the propensity to spontaneously layer as solid films on glass surfaces. The deposited material has been characterized by means of UV-visible, fluorescence emission, circular dichroism spectroscopy and AFM. The reported studies show once more how the stereochemical information stored on a single porphyrin framework can induce the formation of supramolecular chiral architectures, in solution, as well as in solid state. Furthermore, slight modifications on the porphyrin skeleton can influence the aggregation process and the structural features of the final assemblies, leading to solid surfaces featuring different morphologies. These combined aspects can be of great importance for the achievement of solid state chemical sensors with stereoselective properties.

Hemming of Aluminum Alloy Sheets Using Electromagnetic Forming

Hemming is usually the last stage of production for automotive closures, and therefore has a critical effect on the quality of the final assemblies. The insufficient formability of aluminum alloys creates a considerable problem in the hemming process. To address this issue, electromagnetic forming was utilized to hem aluminum alloy sheets. Electromagnetic forming is a high strain rate forming process that is currently being investigated by both academia and industry. Past studies have shown that the formability of metals can be significantly improved during electromagnetic forming, which benefits the hemming of aluminum alloys. This article presents the experimental results of hemming Al 6061-T6 sheets using electromagnetic forming. The effects of the parameters of electromagnetic hemming on the hem quality are discussed. In addition, the numerical simulation results of electromagnetic hemming are presented to enhance the understanding of the process and to determine the efficacy on an industrial scale.

Axis-Oriented, Anatase TiO2 Single Crystals with Dominant {001} and {100} Facets

Owing to wide-ranging industrial applications and fundamental importance, tailored synthesis of well-faceted single crystals of anatase TiO2 with a high percentage of photoactive facets has attracted much research interest. In this work, single crystalline anatase TiO2 has been prepared using hydrothermal conditions with precursors such as TiF4 and TiCl3. Fluorine species (herein HF) are introduced as a stabilizing agent to reduce surface energies of anatase TiO2, especially {001} facets, which leads to a large percentage of the reactive {001} facets exposed in final assemblies or films of titania with the largest exposure area. Anatase TiO2 single crystals with various degrees of truncation are prepared as a result of differences in relative concentration ratios of HF to TiF4. The “rice-like” anatase single crystals with exposed {100} facets were prepared in the system using TiCl3 precursor. Carboxymethyl cellulose (CMC), used as a dispersing agent, helps to control the reaction rate and suppress the agg...