Assembly Machine Research Articles

Killing with proficiency: Integrated post-translational regulation of an offensive Type VI secretion system.

The Type VI secretion system (T6SS) is widely used by bacterial pathogens as an effective weapon against bacterial competitors and is also deployed against host eukaryotic cells in some cases. It is a contractile nanomachine which delivers toxic effector proteins directly into target cells by dynamic cycles of assembly and firing. Bacterial cells adopt distinct post-translational regulatory strategies for deployment of the T6SS. ‘Defensive’ T6SSs assemble and fire in response to incoming attacks from aggressive neighbouring cells, and can utilise the Threonine Protein Phosphorylation (TPP) regulatory pathway to achieve this control. However, many T6SSs are ‘offensive’, firing at all-comers without the need for incoming attack or other cell contact-dependent signal. Post-translational control of the offensive mode has been less well defined but can utilise components of the same TPP pathway. Here, we used the anti-bacterial T6SS of Serratia marcescens to elucidate post-translational regulation of offensive T6SS deployment, using single-cell microscopy and genetic analyses. We show that the integration of the TPP pathway with the negative regulator TagF to control core T6SS machine assembly is conserved between offensive and defensive T6SSs. Signal-dependent PpkA-mediated phosphorylation of Fha is required to overcome inhibition of membrane complex assembly by TagF, whilst PppA-mediated dephosphorylation promotes spatial reorientation and efficient killing. In contrast, the upstream input of the TPP pathway defines regulatory strategy, with a new periplasmic regulator, RtkS, shown to interact with the PpkA kinase in S. marcescens. We propose a model whereby the opposing actions of the TPP pathway and TagF impose a delay on T6SS re-assembly after firing, providing an opportunity for spatial re-orientation of the T6SS in order to maximise the efficiency of competitor cell targeting. Our findings provide a better understanding of how bacterial cells deploy competitive weapons effectively, with implications for the structure and dynamics of varied polymicrobial communities.

A method for thermal characteristics modelling of hob assembly on dry hobbing machine

Gear hobbing is the use of machinery to manufacture external gears. With the booming motor industry, there are more requirements for gear hobbing accuracy than ever before. Thermal error – as a major source of error in a dry hobbing machine – must be effectively compensated to achieve accuracy. Thus, studies on the thermal error of hob assembly are important both in theory and practice. This paper discusses the development of a valid numerical modelling method for the hob assembly of a dry hobbing machine. The equations used to determine the values of heat sources and heat transfer coefficients are given. The temperature field and thermal deformation of the hob assembly were obtained by thermal-structural coupling numerical simulations. Numerical results showed that the deformation can maximally reach to 94.5 µm, which is non-ignorable in the thermal deformation analysis of the whole dry gear hobbing machine. Subsequently, by comparing the simulation results and experimental data, the newly proposed method to determine the forced convection heat transfer coefficient proved more fitting for describing the airflow pattern inside the gear hobbing zone. The satisfactory agreement between simulation results and experimental data also suggests that the numerical analysis method proposed in this paper can provide an effective research tool to optimize the design of hob assembly. And the results obtained by the proposed method can be used for thermal error modelling in real error compensation.

Minimizing total completion time in the assembly scheduling problem

Abstract This paper studies a two-stage assembly problem to minimize the total completion time. The two-stage assembly system consists of multiple machines in the first stage, and an assembly machine in the second stage. Each job consists of multiple components. In the first stage each component is processed on the dedicated machine. In the second stage, the processed components of each job are shipped and assembled into a product on the assembly machine. This system is a generalization of flowshop, which has practical applications in assembly-driven manufacturing. The objective is to establish an efficient schedule minimizing the total completion time. Six lower bounds are proposed and evaluated in a branch-and-bound algorithm. Also, four efficient heuristic algorithms are developed to generate near-optimal schedules. The computational results show that the derived B&B and heuristic algorithms perform very well within reasonable time.

Non-collapsible and collapsible systems for finishing buildings, constructions and their indoors

Engineering research activity is considering mechanical joint as the process of fabrication a product of machine elements and assembly units (nodes) by physically combining them into a single piece, i.e. as a composition. In engineering systems, which consists construction industry and its production (buildings, constructions, roads), use two fundamentally different ways of mechanical joint: non-collapsible and collapsible. Non-collapsible joint is a combining known components to give them necessary mechanical properties and decent appearance. This combining cannot be disassembled to source components without destruction. Non-collapsible joints achieved by using technological processes of assembling (gluing, welding, soldering, riveting, applying, painting, spraying, pressing, etc.) of different materials and machine elements. That’s why some architects relate non-collapsible objects to monolithic and they consider their recycling as difficult and expensive process. Compression joints on self-locking fittings can be considered as non-collapsible as well. A compression connection cannot be disassembled without destroying. Collapsible joint differs from non-collapsible with these features:- You can disassemble it to source components according to a prior technology, identify and change defective elements or add some other components.- It requires periodic inspection and maintenance because climatic conditions (temperature changes, pressure changes, wind loads, etc.) and the specificity of operation of this joint lead to a decrease of its mechanical properties.- It is forbidden to make monolithic, therefore, collapsible joints are mounted in an accessible way.

June 1993

Education & manufacturing; lobbying advice; Booth Brunswick reamers win; 5-axis laser profiler/welder first; CAM software developments; cylinder head auto assembly machines; potential of advanced DNC; Taiwan’s image make-over, plus more

A novel pneumatic gripper for in-hand manipulation and feeding of lightweight complex parts\u2014a consumer goods case study

This paper discusses the design and implementation of a robotic gripper that uses compressed air to (a) orient the parts in the desired grasping position, (b) guide the parts inside a grasping mechanism and (c) feed the parts to a track conveyor with sufficient accuracy. The novelty of the approach lays in the ability to perform in-hand manipulation of the object by the gripper allowing to pick randomly placed objects that have a complex geometry. Unlike existing ‘pick and place’ operations which are mainly focused on flat objects that require minimal manipulation (rotation around vertical axis), the gripper can re-orient the parts itself, minimizing the robot’s motion. The major components of the gripper are 3D printed, allowing fast customization for different products. The manipulation and gripping mechanisms have been inspired by an application in the consumer goods industry involving the feeding of shaver handles to an assembly machine. The findings indicate that the proposed solution can be an alternative to part-dedicated, high-cost feeding equipment that is currently used.

Functional and Biochemical Characterization of Dib1's Role in Pre-Messenger RNA Splicing

The spliceosome is a dynamic macromolecular machine that undergoes a series of conformational rearrangements as it transitions between the several states required for accurate splicing. The transition from the B to Bact is a key part of spliceosome assembly and is defined by the departure of several proteins, including essential U5 component Dib1. Recent structural studies suggest that Dib1 has a role in preventing premature spliceosome activation, as it is positioned adjacent to the U6 snRNA ACAGAGA and the U5 loop I, but its mechanism is unknown. Our data indicate that Dib1 is a robust protein that tolerates incorporation of many mutations, even at positions thought to be key for its folding stability. However, we have identified two temperature-sensitive mutants that stall in vitro splicing prior to the first catalytic step and block assembly at the B complex. In addition, Dib1 readily exchanges in splicing extracts despite being a central component of the U5 snRNP, suggesting that the binding site of Dib1 is flexible. Structural analyses show that the overall conformation of Dib1 and the mutants are not affected by temperature, so the temperature sensitive defects most likely result from altered interactions between Dib1 and other spliceosomal components. Together, these data lead to a new understanding of Dib1's role in the B to Bact transition and provide a model for how dynamic protein–RNA interactions contribute to the correct assembly of a complex molecular machine.

Antimicrobial Agents That Inhibit the Outer Membrane Assembly Machines of Gram-Negative Bacteria.

Gram-negative pathogens, such as Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter baumannii, pose a serious threat to public health worldwide, due to high rates of antibiotic resistance and the lack of development of novel antimicrobial agents targeting Gram-negative bacteria. The outer membrane (OM) of Gram-negative bacteria is a unique architecture that acts as a potent permeability barrier against toxic molecules, such as antibiotics. The OM is composed of phospholipids, lipopolysaccharide (LPS), outer membrane β-barrel proteins (OMP), and lipoproteins. These components are synthesized in the cytoplasm or in the inner membrane, and are then selectively transported to the OM by the specific transport machines, including the Lol, BAM, and Lpt pathways. In this review, we summarize recent studies on the assembly systems of OM components and analyze studies for the development of inhibitors that target these systems. These analyses show that OM assembly machines have the potential to be a novel attractive drug target of Gram-negative bacteria.

Scale-up of amine-containing thin-film composite membranes for CO2 capture from flue gas

Membrane technology is a cost-effective and energy-efficient separation process for CO2 removal from flue gas. Recently, there have been remarkable advances in the development of polyvinylamine (PVAm)/piperazine glycinate (PG)-containing facilitated transport membranes for CO2 removal. The advanced PVAm/PG-containing membranes have demonstrated desirably high CO2/N2 selectivity of greater than 140 and good CO2 permeance of > 700 GPU (1 GPU = 10−6 cm3 (STP)/(s cm2 cmHg)) at the typical flue gas temperature of 57 °C. This work investigated the scale-up fabrication of the PVAm/PG-containing membranes and demonstrated it successfully. Effective and efficient continuous fabrication of the membranes in a roll-to-roll manner was developed using the thin-film coating (TFC) assembly of the pilot-scale machine at Ohio State. The design of the TFC assembly was improved and several operating parameters were optimized for the fabrication with desirable membrane thickness and gas transport performance. A total of > 2000 feet long and 14-in. wide membranes with a selective layer thickness of < 200 nm was successfully fabricated. In addition, small representative samples taken from the scale-up membranes were tested, showing the CO2 permeance and CO2/N2 selectivity at 57 °C in reasonably good agreement with those obtained from the lab-synthesized membranes.

A Magnetic-Field-Assisted Milli-Scale Robotic Assembly Machine: An Approach to Parallel Robotic Automation Systems.

Utilizing large numbers of microrobots to heterogeneously integrate small devices to build advanced structures has long been a goal in the field of manufacturing automation. In this paper, we demonstrate a novel milli-scale robotic assembly machine with highly parallel capabilities and assisted with a programmable magnetic field. The prototype machine consists of a 16 × 16 array of electromagnets. Using this machine, we have successfully demonstrated the manipulation of up to nine milli-scale robots simultaneously. Moreover, two microrobots have been operated to demonstrate the proof of concept of two simultaneous pick-and-place light-emitting diodes (LEDs). The design and modeling of the microrobots is discussed.

Monoclonal antibody targeting the β-barrel assembly machine of Escherichia coli is bactericidal

The folding and insertion of integral β-barrel membrane proteins into the outer membrane of Gram-negative bacteria is required for viability and bacterial pathogenesis. Unfortunately, the lack of selective and potent modulators to dissect β-barrel folding in vivo has hampered our understanding of this fundamental biological process. Here, we characterize a monoclonal antibody that selectively inhibits an essential component of the Escherichia coli β-barrel assembly machine, BamA. In the absence of complement or other immune factors, the unmodified antibody MAB1 demonstrates bactericidal activity against an E. coli strain with truncated LPS. Direct binding of MAB1 to an extracellular BamA epitope inhibits its β-barrel folding activity, induces periplasmic stress, disrupts outer membrane integrity, and kills bacteria. Notably, resistance to MAB1-mediated killing reveals a link between outer membrane fluidity and protein folding by BamA in vivo, underscoring the utility of this antibody for studying β-barrel membrane protein folding within a living cell. Identification of this BamA antagonist highlights the potential for new mechanisms of antibiotics to inhibit Gram-negative bacterial growth by targeting extracellular epitopes.

Analysis method of dynamics and structure optimization for sealing mechanism under reducing vibration condition

The paper highlights the importance of optimal design model in the design evaluation of complex sealing mechanism. Sealing mechanism of the high-speed assembly machine is taken as the research object and construct rigid-flexible coupling dynamic equation. Dynamic characteristics of the sealing mechanism are analyzed by MATLAB. The maximum dynamic stress and reducing the acceleration of the end F are regarded as the optimization object. Cam profile curve parameter and the link cross section parameter are designed as the variables to construct the optimization design model of the whole sealing mechanism, and nonlinear constraint problem is transformed into a linear constraint problem. Based on the MATLAB genetic algorithm toolbox, the optimal design model of the sealing mechanism is solved, and the optimal result is obtained.

Analysis and optimization of assembly precision-cost model based on 3D tolerance expression

PurposeThis paper aims to comprehensively achieve the requirements of high assembly precision and low cost, a precision-cost model of assembly based on three-dimensional (3D) tolerance is established in this paper.Design/methodology/approachThe assembly precision is related to the tolerance of parts and the deformation of matching surfaces under load. In this paper, the small displacement torsor (SDT) theory is first utilized to analyze the manufacturing tolerances of parts and the assembly deformation deviation of matching surface. In the meanwhile, the extracting method of SDT parameters is proposed and the assembly precision calculation model based on the 3D tolerance is established. Second, an integrated optimization model based on the machining cost, assembly cost (mapping the deviation domain to the SDT domain) and quality loss cost is built. Finally, the practicability of the precision-cost model is verified by optimizing the horizontal machining center.FindingsThe assembly deviation has a great influence on cost fluctuation. By setting the optimization objective to maximize the assembly precision, the optimal total cost is CNY 72.77, decreasing by 16.83 per cent from the initial value, which meets economical requirements. Meanwhile, the upper bound of each processing tolerance is close to the maximum value of 0.01 mm, indicating that the load deformation can be offset by appropriately increasing the upper bound of the tolerance, but it is necessary to strictly restrict the manufacturing tolerances of lower parts in a reasonable range.Originality/valueIn this paper, a 3D deviation precision-cost model of assembly is established, which can describe the assembly precision more accurately and achieve a lower cost compared with the assembly precision model based on rigid parts.

Lipoprotein Transport: Greasing the Machines of Outer Membrane Biogenesis: Re-Examining Lipoprotein Transport Mechanisms Among Diverse Gram-Negative Bacteria While Exploring New Discoveries and Questions.

The Gram-negative outer membrane (OM) is a potent permeability barrier against antibiotics, limiting clinical options amid mounting rates of resistance. The Lol transport pathway delivers lipoproteins to the OM. All the OM assembly machines require one or more OM lipoprotein to function, making the Lol pathway central for all aspects of OM biogenesis. The Lol pathways of many medically important species clearly deviate from the Escherichia coli paradigm, perhaps with implications for efforts to develop novel antibiotics. Moreover, recent work reveals the existence of an undiscovered alternate route for bringing lipoproteins to the OM. Here, lipoprotein transport mechanisms, and the quality control systems that underpin them, is re-examined in context of their diversity.

Reverse engineering of wörner type drilling machine structure.

A product design needs to be modified based on the conditions of production facilities and existing resource capabilities without reducing the functional aspects of the product itself. This paper describes the reverse engineering process of the main structure of the wörner type drilling machine to obtain a machine structure design that can be made by resources with limited ability by using simple processes. Some structural, functional and the work mechanism analyzes have been performed to understand the function and role of each basic components. The process of dismantling of the drilling machine and measuring each of the basic components was performed to obtain sets of the geometry and size data of each component. The geometric model of each structure components and the machine assembly were built to facilitate the simulation process and machine performance analysis that refers to ISO standard of drilling machine. The tolerance stackup analysis also performed to determine the type and value of geometrical and dimensional tolerances, which could affect the ease of the components to be manufactured and assembled

굴양식용 수하연 자동조립기 개발

굴양식용 수하연 자동조립기 개발

A Study on the Drilling Performance of the Assembly Machine for the an Aircraft’s Main Wings

A Study on the Drilling Performance of the Assembly Machine for the an Aircraft’s Main Wings

Substrate binding to BamD triggers a conformational change in BamA to control membrane insertion

The β-barrel assembly machine (Bam) complex folds and inserts integral membrane proteins into the outer membrane of Gram-negative bacteria. The two essential components of the complex, BamA and BamD, both interact with substrates, but how the two coordinate with each other during assembly is not clear. To elucidate aspects of this process we slowed the assembly of an essential β-barrel substrate of the Bam complex, LptD, by changing a conserved residue near the C terminus. This defective substrate is recruited to the Bam complex via BamD but is unable to integrate into the membrane efficiently. Changes in the extracellular loops of BamA partially restore assembly kinetics, implying that BamA fails to engage this defective substrate. We conclude that substrate binding to BamD activates BamA by regulating extracellular loop interactions for folding and membrane integration.

Design System of Cell Type Assembly Machine with Dual Arms Robot by GA

Design System of Cell Type Assembly Machine with Dual Arms Robot by GA

A Modelling Method of Bolt Joints Based on Basic Characteristic Parameters of Joint Surfaces

Bolt joints are common in machine tools and have a direct impact on the overall performance of the tools. Therefore, the understanding of bolt joint characteristics is essential for improving machine design and assembly. Firstly, According to the experimental data obtained from the experiment, the stiffness curve formula was fitted. Secondly, a finite element model of unit bolt joints such as bolt flange joints, bolt head joints, and thread joints was constructed, and lastly the stiffness parameters of joint surfaces were implemented in the model by the secondary development of ABAQUS. The finite element model of the bolt joint established by this method can simulate the contact state very well.