Selective Assembly Research Articles

Автоматизация процесса комплектования оптических элементов при селективной сборке фотообъективов

Автоматизация процесса комплектования оптических элементов при селективной сборке фотообъективов

A new selective assembly model for achieving specified clearance in radial assembly

Manufacturing and assembling of high precision assemblies to achieve the specified clearance pose great challenge to the engineers. A complex assembly of piston, piston ring and cylinder is considered for analysis. In this assembly, the assembly clearance is specified to avoid thin oil film or scuffing. To achieve the specified clearance it is required that the individual component tolerances have to be reduced, which may not be possible due to economic considerations. In this paper, a new selective assembly model using Genetic Algorithm is proposed to achieve specified clearance in radial assembly with minimum surplus parts.

Chromosomal Junction Detection from Whole-Genome Sequencing on Formalin-Fixed, Paraffin-Embedded Tumors

DNA junctions (DNAJs) frequently impact clinically relevant genes in tumors and are important for diagnostic and therapeutic purposes. Although routinely screened through fluorescence in situ hybridization assays, such testing only allows the interrogation of single-gene regions or known fusion partners. Comprehensive assessment of DNAJs present across the entire genome can only be determined from whole-genome sequencing. Structural variance analysis from whole-genome paired-end sequencing data is, however, frequently restricted to copy number changes without DNAJ detection. Through optimized whole-genome sequencing and specialized bioinformatics algorithms, complete structural variance analysis is reported, including DNAJs, from formalin-fixed DNA. Selective library assembly from larger fragments (>500 bp) and economical sequencing depths (300 to 400 million reads) provide representative genomic coverage profiles and increased allelic coverage to levels compatible with DNAJ calling (40× to 60×). Although consistently fragmented, more recently formalin-fixed, specimens (<2 years' storage) revealed consistent populations of larger DNA fragments. Optimized bioinformatics efficiently detected >90% of DNAJs in two prostate tumors (approximately 60% tumor) previously analyzed by mate-pair sequencing on fresh frozen tissue, with evidence of at least one spanning-read in 99% of DNAJs. Rigorous masking with data from unrelated formalin-fixed tissue progressively eliminated many false-positive DNAJs, without loss of true positives, resulting in low numbers of false-positive passing current filters. This methodology enables more comprehensive clinical genomics testing on formalin-fixed clinical specimens.

Component ordering policies for selective assembly

Selective assembly is an approach in which high-precision assemblies can be produced from relatively low-precision components or subassemblies. This research investigates component ordering policies for fixed-bin selective-assembly processes that consider the stochastic nature of the binning process as well as stochastic demand. The distributional aspects of the assembly process are identified, and an approximation of the number of assemblies completed is provided utilising extreme-value theory. The order quantity can then be determined to meet demand with a given service level; an implicit-enumeration procedure is presented to illustrate this process. Computational results illustrate that this is an effective approach for controlling component inventories.

SCARA ROBOT LINKS LENGTH OPTIMIZATION BY USING MATLAB AND VERIFICATION WITH SIMMECHANICS AND SOLIDWORKS

This paper aims for optimizing links length that consumed the minimum energy, for a customized Selective Compliant Assembly Robot Arm (SCARA) robot. Nine link length combinations are tested and simulated.&nbsp; This research is a part of a project of designing a robotic arm for a packing task. Kinematic and dynamic studies are performed for a 2R robotic arm. The results of kinematic study which are angular displacement, angular velocity and angular acceleration for each joint are determined and exported to the dynamic study to obtain the torque and power consumed. The dynamic study is performed with the aid of MATLAB code, MATLAB/SimMechanics and Solidworks are used to simulate and analyze the dynamic of the robotic arm. The energy consumed for each link length combination using the three methods is calculated.

Diaphragm-Embedded Optical Fiber Sensors: A Review and Tutorial

In this article, we thoroughly discuss many aspects of diaphragm-embedded optical fiber sensors covering industrial, robotics and medical applications: from the modeling to field applications, which also include sensor fabrication (such as interferometers, grating-based sensors, intensity variation sensors) in standard and specialty optical fibers, diaphragm and optical fiber materials thermal and mechanical characterizations. The operation limits of the sensors, interrogation techniques and the measurement possibilities that such sensors provide are also discussed. We expect that this review and tutorial provide valuable information regarding the optical fiber sensor approach, material selection and sensor assembly for the development of diaphragm-embedded optical fiber sensors.

Template Dissolution Interfacial Patterning of Single Colloids for Nanoelectrochemistry and Nanosensing.

Deterministic positioning and assembly of colloidal nanoparticles (NPs) onto substrates is a core requirement and a promising alternative to top-down lithography to create functional nanostructures and nanodevices with intriguing optical, electrical, and catalytic features. Capillary-assisted particle assembly (CAPA) has emerged as an attractive technique to this end, as it allows controlled and selective assembly of a wide variety of NPs onto predefined topographical templates using capillary forces. One critical issue with CAPA, however, lies in its final printing step, where high printing yields are possible only with the use of an adhesive polymer film. To address this problem, we have developed a template dissolution interfacial patterning (TDIP) technique to assemble and print single colloidal AuNP arrays onto various dielectric and conductive substrates in the absence of any adhesion layer, with printing yields higher than 98%. The TDIP approach grants direct access to the interface between the AuNP and the target surface, enabling the use of colloidal AuNPs as building blocks for practical applications. The versatile applicability of TDIP is demonstrated by the creation of direct electrical junctions for electro- and photoelectrochemistry and nanoparticle-on-mirror geometries for single-particle molecular sensing.

Toehold-Mediated Selective Assembly of Compact Discrete DNA Nanostructures.

Production of small discrete DNA nanostructures containing covalent junctions requires reliable methods for the synthesis and assembly of branched oligodeoxynucleotide (ODN) conjugates. This study reports an approach for self-assembly of hard-to-obtain primitive discrete DNA nanostructures-"nanoethylenes", dimers formed by double-stranded oligonucleotides using V-shaped furcate blocks. We scaled up the synthesis of V-shaped oligonucleotide conjugates using pentaerythritol-based diazide and alkyne-modified oligonucleotides using copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) and optimized the conditions for "nanoethylene" formation. Next, we designed nanoethylene-based "nanomonomers" containing pendant adapters. They demonstrated smooth and high-yield spontaneous conversion into the smallest cyclic product, DNA tetragon aka "nano-methylcyclobutane". Formation of DNA nanostructures was confirmed using native polyacrylamide gel electrophoresis (PAGE) and atomic force microscopy (AFM) and additionally studied by molecular modeling. The proposed facile approach to discrete DNA nanostructures using precise adapter-directed association expands the toolkit for the realm of DNA origami.

An Integrated Product-Process Design Approach Considering Material Selection and Product Assembly

Nowadays, industries face very strong challenges because of the high competitiveness between them. In fact, they are required to offer products with high quality and minimum cost in the minimum time. Since most of the characteristics and costs of the product and its manufacturing process are fixed in the design phase, this paper is focused on this strategic phase. Indeed, a new integrated product design approach is presented. It considers at the same time design requirements, materials characteristics, manufacturing parameters and the assembly process specifications. The developed approach is quantitative. Actually, the decision making is based on all its steps on objective and subjective indicators. To validate the integrated approach, a case study on the Schrader Robot is developed. This application allows to choose the most appropriate materials, manufacturing processes and assembly solution of its different components.

The relative contribution of non-selection and selection processes in marine benthic assemblages

We tested the hypothesis that the ubiquity of marine meiofaunal nematodes and their indiscriminate passive dispersal create assemblages that are less limited by its environment; whereas the relatively smaller population sizes of macrofauna, associated with their ability to track environmental conditions before settlement, renders their distribution more environmentally-restricted. We compared the empirical distribution of macrofauna and nematode species with that of communities simulated under different assumptions of selection (e.g. environmental filtering) and non-selection (e.g. dispersal limitation) processes. Selection processes were the prime driver of both meio- and macrofauna assemblages, with rare species strongly contributing to this component. The total number of species explained by non-selection processes was 27% higher in nematodes than in macrofauna. Our results underline the importance of a species-level approach to determine the contribution of selection and non-selection assembly processes. Moreover, they highlight the important yet overlooked role of dispersal and stochastic processes in determining species dynamics.

Radical Cyclic [3]Daisy Chains

Summary Mechanically interlocked molecules (MIMs) that undergo controllable internal motions of their component parts in more than one dimension are rare entities in the molecular world. Cyclic [2]daisy chains ([c2]DCs) are a class of MIMs that have been identified as prototypes for molecular muscles. It remains, however, a challenge to synthesize [cn]DCs with n > 2 selectively and efficiently. Herein, we report the design and synthesis of [c3]DCs employing radical and anionic templates. Two mechanically interlocked [c3]DCs with 18 positive charges were obtained in >90% yields. One [c3]DC displayed good air stability in its radical cationic form, while the other underwent reversible “co-conformational” switching between open macrocyclic and closed trisarm-shaped forms under electrochemical control. These findings provide not only two-dimensional MIMs with attractive electronic and switchable properties, but also a starting point for the design of extended molecular arrays, which could become the forerunners of adjustable molecular nets and breathable molecular membranes.

Model of selective assembly process of rod-piston group parts of internal combustion engines

Functioning of conrod-piston group of internal combustion engine is considered. It is shown that the main method of assembly of this unit is selective assembly, which provides the required accuracy of parts joints. The scheme of the assembly set-making is given, a mathematical model of the process of its selective assembly with the selected strategy is built. As a strategy, a single-variant set-making is proposed, in which the assembly is carried out from the groups of the same numbers. The constructed model allows to determine the process indicators, in particular, the probability of obtaining suitable assembled sets, the probability of incomplete elements, forming work in progress and preliminary scrappage. The task of optimal assembly of rod-piston group at specified values of extended tolerances and arrangement of tolerance intervals by rational selection of boundaries of selective groups is set. The solution of this task is given.

Synthesis and binder-free assembly of SrFe12O19 nano-platelets for wafer-scale patterning of magnetic components

Monolithic integration of high-frequency magnetic components such as hexaferrite circulators at the wafer scale can lead to a significant improvement in radio frequency (RF) circuit performance and functionality. However, current methods to monolithically integrate hexaferrite films, such as liquid phase epitaxy, require high temperature (> 900 °C) annealing to create crystalline alignment, which is not compatible with integrated circuit process temperatures (< 350 °C) or thick patterned films (> 50 μm). In this work, we report the synthesis of pure phase, faceted, and high crystallinity hexaferrite [SrFe12O19] nano-platelets using a direct hydrothermal approach, followed by self-assembly of binder free SrFe12O19 films with high film density and high magnetic isotropy. The nano-platelets exhibit high staturation magnetization (~ 60 emu/g) and coercivity (Hc) of 815 Oe. The magnetic films exhibit dense nano-particle concentration and a magnetic squareness (Mr/Ms) of 0.7. They can be patterned using a selective assembly process through a thick photoresist mask. Thicknesses of up to 70 μm have been deposited on 4-in.-diamater wafers.

Optimization of Selective Assembly for Shafts and Holes Based on Relative Entropy and Dynamic Programming.

Selective assembly is the method of obtaining high precision assemblies from relatively low precision components. For precision instruments, the geometric error on mating surface is an important factor affecting assembly accuracy. Different from the traditional selective assembly method, this paper proposes an optimization method of selective assembly for shafts and holes based on relative entropy and dynamic programming. In this method, relative entropy is applied to evaluate the clearance uniformity between shafts and holes, and dynamic programming is used to optimize selective assembly of batches of shafts and holes. In this paper, the case studied has 8 shafts and 20 holes, which need to be assembled into 8 products. The results show that optimal combinations are selected, which provide new insights into selective assembly optimization and lay the foundation for selective assembly of multi-batch precision parts.

Effect of Uncertainty in Basing Hydraulic Prop Rod on Dimensional Wear of its Basic Surfaces

Hydraulic power cylinders are the main bearing elements of powered supports at mining enterprises, ensuring reliable fixation of the roof in the required working position, as well as providing advancement of the support in the face. Thus, hydraulic power cylinders ensure stoping safety, so strict requirements are im-posed on them both in terms of workmanship and operational reliability. To ensure reliability and efficiency of powered support operation in faces, it is necessary to ensure stable service life of their hydraulic props, which mainly depends on the quality of manufacturing of mating surfaces and the accuracy of assembling functional joints. The required accuracy of hydraulic prop joints is achieved by selective assembly, which allows ensuring the specified technical requirements and service life of the joints. At the same time, along with the issues of ensuring the accuracy of assembling the props to provide proper safety of the face operation, it is extremely important to identify and analyze the causes of dimensional wear of critical parts of the joints, leading to decreasing service life of the hydraulic props in the course of exploitation. In the paper, using the methods of the analytical theory of bases, the reasons for formation of positional variations of the parts of the powered support hydraulic prop joints in the course of assembling and operation of the unit are identified and described. It was found that arising mismatches and formation of local stress zones on the cylinders, pistons and rods, characterized by intense wear, occurs due to the uncertainty of basing (positioning) of rod and piston in hydraulic cylinder. The dependencies allowing calculating deviation of the rod axis from the required position, taking into account the initial clearance gap in the joints and the adopted design parameters of the hydraulic cylinder, have been obtained.

Modular metabolite assembly in Caenorhabditis elegans depends on carboxylesterases and formation of lysosome-related organelles.

Signaling molecules derived from attachment of diverse metabolic building blocks to ascarosides play a central role in the life history of C. elegans and other nematodes; however, many aspects of their biogenesis remain unclear. Using comparative metabolomics, we show that a pathway mediating formation of intestinal lysosome-related organelles (LROs) is required for biosynthesis of most modular ascarosides as well as previously undescribed modular glucosides. Similar to modular ascarosides, the modular glucosides are derived from highly selective assembly of moieties from nucleoside, amino acid, neurotransmitter, and lipid metabolism, suggesting that modular glucosides, like the ascarosides, may serve signaling functions. We further show that carboxylesterases that localize to intestinal organelles are required for the assembly of both modular ascarosides and glucosides via ester and amide linkages. Further exploration of LRO function and carboxylesterase homologs in C. elegans and other animals may reveal additional new compound families and signaling paradigms.

Ternary MOF-on-MOF heterostructures with controllable architectural and compositional complexity via multiple selective assembly

Assembly of different metal-organic framework (MOF) building blocks into hybrid MOF-on-MOF heterostructures is promising in chemistry and materials science, however the development of ternary MOF-on-MOF heterostructures with controllable architectural and compositional complexity is challenging. Here we report the synthesis of three types of ternary MOF-on-MOF heterostructures via a multiple selective assembly strategy. This strategy relies on the choice of one host MOF with more than one facet that can arrange the growth of a guest MOF, where the arrangement is site-selective without homogenous growth of guest MOF or homogenous coating of guest on host MOF. The growth of guest MOF on a selected site of host MOF in each step provides the opportunity to further vary the combinations of arrangements in multiple steps, leading to ternary MOF-on-MOF heterostructures with tunable complexity. The developed strategy paves the way towards the rational design of intricate and unprecedented MOF-based superstructures for various applications.

Performance estimation of computed torque control for surgical robot application

In the current paradigm, the development in robotic technology has a huge impact to revolutionize the medical domain. Surgical robots have greater advantages over surgeon such as reduced operating time, reduced tremor, less blood loss, and high dexterity. To perform different operations during surgery a base robot is required with the task-specific end effector. In this paper, the selective compliant assembly robot arm (SCARA) has been considered as the base robot and the complete mathematical modeling of the robot is illustrated. The equation of Kinematics is derived from the D-H notation. SCARA dynamic model is derived from Euler Lagrange. In order to achieve trajectory tracking the Computed Toque Control technique (CTC) applied to the SCARA manipulator. The performance of the CTC technique for trajectory tracking of each joint of the SCARA robot has evaluated in contrast with tuned PD and PID controller. The simulation results were discussed and verified using MATLAB simulation software.

A New Position Detection and Status Monitoring System for Joint of SCARA

High-precision position detection of joint and status monitoring of speed reduction gearbox (SRG) are two key technologies in the research and development of selective compliant assembly robot arm (SCARA). The existing schemes have some problems, such as the large occupation of space, high cost, complex implementation, lack of status monitoring, etc. Therefore, first, in order to get the accurate position information of joint when the SCARA is powered up at the first time, a new combined incremental encoder with unevenly distributed multiple indexing signals and initial position detection method is proposed. Second, in order to get the accurate position information and monitor the operation status of the SRG during the positioning operation, a real-time position detection and status monitoring method based on the transmission error using dual incremental encoder is proposed. The general design principle has been given, and various experimental results have confirmed the effectiveness of the proposed solution. The proposed new combined incremental encoder has the advantage of small occupied space, easy realization, and low cost. The proposed position detection and status monitoring method not only realizes the high-precision detection of the joint position but also provides the key data for the monitoring of the running state of the SRG.

Multiple capsid protein binding sites mediate selective packaging of the alphavirus genomic RNA

The alphavirus capsid protein (Cp) selectively packages genomic RNA (gRNA) into the viral nucleocapsid to produce infectious virus. Using photoactivatable ribonucleoside crosslinking and an innovative biotinylated Cp retrieval method, here we comprehensively define binding sites for Semliki Forest virus (SFV) Cp on the gRNA. While data in infected cells demonstrate Cp binding to the proposed genome packaging signal (PS), mutagenesis experiments show that PS is not required for production of infectious SFV or Chikungunya virus. Instead, we identify multiple Cp binding sites that are enriched on gRNA-specific regions and promote infectious SFV production and gRNA packaging. Comparisons of binding sites in cytoplasmic vs. viral nucleocapsids demonstrate that budding causes discrete changes in Cp-gRNA interactions. Notably, Cp’s top binding site is maintained throughout virus assembly, and specifically binds and assembles with Cp into core-like particles in vitro. Together our data suggest a model for selective alphavirus genome recognition and assembly.