Assembly Phase Research Articles

INITIAL INTEGRAL PRODUCT AND ASSEMBLY STRUCTURING: A CASE STUDY

AbstractModular product structuring has been proven an effective way to satisfy a high sales variety with low internal product and process complexity but is usually carried out on existing structures. To support the modular new product development, this contribution shows the initial structuring of integrated product and assembly structures based on a variance-oriented product structure. With help of a perspective-based modularization approach, consolidating the product life phases of procurement, assembly and sales, modular product and process structures are developed within an industry case study.

A tracer-based algorithm for automatic generation of seafloor age grids from plate tectonic reconstructions

The age of the ocean floor and its time-dependent age distribution control fundamental features of the Earth, such as bathymetry, sea level and mantle heat loss. Recently, the development of increasingly sophisticated reconstructions of past plate motions has provided models for plate kinematics and plate boundary evolution back in geological time. These models implicitly include the information necessary to determine the age of ocean floor that has since been lost to subduction. However, due to the lack of an automated and efficient method for generating global seafloor age grids, many tectonic models, most notably those extending back into the Paleozoic, are published without an accompanying set of age models for oceanic lithosphere. Here we present an automatic, tracer-based algorithm that generates seafloor age grids from global plate tectonic reconstructions with defined plate boundaries. Our method enables us to produce novel seafloor age models for the Paleozoic’s lost ocean basins. Estimated changes in sea level based on bathymetry inferred from our new age grids show good agreement with sea level record estimations from proxies, providing a possible explanation for the peak in sea level during the assembly phase of Pangea. This demonstrates how our seafloor age models can be directly compared with observables from the geologic record that extend further back in time than the constraints from preserved seafloor. Thus, our new algorithm may also aid the further development of plate tectonic reconstructions by strengthening the links between geological observations and tectonic reconstructions of deeper time.

Jlab Chl1 2K Cold Box Replacement

A new sub-atmospheric cold box (SC1R), which hosts five technologically superior, water-cooled compressors and one similar 4K-2K refrigeration recovery heat exchanger, was proposed in July 2017, to replace the existing 2K cold box. The design of the new 2K cold box and the external support system have been completed. The project is in the fabrication and assembly phase, which will be completed at JLab. We present the design features, fabrication, installation and commissioning schedule for the new 2K cold box.

Experiences during Design, Fabrication, Assembly and Factory Acceptance Test of the ITER Cryoplant Termination Cold Box

The ITER Cryodistribution (CD) system distributes cryogenic power from the cryoplant to the applications, namely superconducting magnets, cryopumps, etc. The ITER CD system comprises seven cold boxes of which the Cryoplant Termination Cold Box (CTCB) is the largest one. The CTCB plays a pivotal role in distributing the cold helium fluid with the highest mass flow rates of 4 kg/s coming from one of the 80 K plants to the applications. The physical connection between the CTCB and different applications is through nine cryolines (CLs) having diameters ranging from 0.45 m to 1.0 m. The CTCB has been manufactured and assembled with various large size components such as electrical heater system of 600 kW capacity, cryogenic control valves of size DN200, bubble panel thermal shield (TS) made of stainless steel, etc. The CTCB, which withstands interface loads of ∼1.4 times of its own weight, has been analysed for its functional and thermo-structural requirements under various load conditions. Components & subsystems were manufactured and factory tested individually in various locations in Europe and India to be finally assembled in one place. The CTCB has also been integrally tested, of which major activities were the pressure and helium leak tightness tests, followed by functionality checks of all instruments. The present paper describes the challenges involved and how they were resolved as well as lesson learnt during the design, fabrication, assembly, and factory acceptance test (FAT) phase of the CTCB project.

Accurate estimation of prediction models for operator-induced defects in assembly manufacturing processes

The presence of defects in industrial manufacturing may compromise the final quality and cost of a product. Among all possible defect causes, human errors have significant effects on the performances of assembly systems. Much research has been conducted in recent years focusing on the problem of defect generation in assembly processes, considering the close connection between assembly complexity and human errors. It was observed that the relationship between the average number of defects introduced during each assembly phase and the related assembly complexity follows a power-law relationship. Accordingly, many authors proposed a data logarithmic transformation in order to linearize the mathematical model. However, as has already been discussed in literature, when the model is retransformed in the original form a significant bias may occur, leading to completely wrong predictions. In this paper, the bias due to the logarithmic transformation of models for predicting defects in assembly is analyzed and discussed. Two alternative methods are proposed and compared to overcome this drawback: the use of a bias correction factor to the retransformed fitted values and a power-law nonlinear regression model. The latter has proved to be the best approach to predict defects with few non-repeated data and affected by high variability, such as in the case under study.

Influence of pore architectures of silk fibroin/collagen composite scaffolds on the regeneration of osteochondral defects in vivo.

The regeneration of osteochondral defects faces great challenges because of the limited self-regenerative capabilities of cartilage tissues. In situ inductive regeneration can be realized using bioactive scaffolds combined with endogenous reparative cells. Cell migration could be significantly facilitated by scaffolds with oriented channels. For this purpose, silk fibroin (SF) was composited with collagen (Col) to fabricate extracellular matrix (ECM)-mimetic SF/Col composite scaffolds with random pores, radially aligned pores or axially aligned pores by ice-templated assembly and temperature gradient-guided thermally-induced phase separation. Scanning electron microscopy (SEM) observation confirmed the random and aligned architectures in the respective scaffolds. The three kinds of SF/Col composite scaffolds exhibited a porous structure with a porosity of ∼85%, an appropriate elastic modulus with mechanical anisotropy in the aligned scaffolds, and good biocompatibility. The oriented channels could improve in vivo cell migration and infiltration. During the tissue remodeling processes, the regeneration of osteochondral tissues particularly cartilage was obviously faster in the radially aligned scaffold group than in the other two groups. Nevertheless, satisfactory regeneration was achieved in the two aligned scaffold groups with hyaline cartilage formation at 18 weeks post-surgery, while a hybrid of hyaline cartilage and fibrocartilage was formed in the random scaffold group.

Basic Quantum Field Model of the Self-Organization of Microtubules in Eukaryotic Cells

The background of this contribution is the ongoing extended debate over quantum effects in the biology since decades. Typical examples of the quantum biology are photosynthesis, enzymatic activities, bird navigation and especially the coherent movement of microtubules. The reason for all these effects is dominantly the quantum coherence of waves. The objective of this contribution is the quantum description of the instability dynamics of microtubules at their assembly and disassembly phases during the interphase. The corresponding theoretical investigations of this article confirm the existence of quantum coherence of microtubules. Experimental results assert such vibrations of microtubules by the observation of γ-waves in the human brain generated by bundles of microtubules. Tubulin subunits and the accessory proteins are of nano size; therefore, they are modeled as field quanta in the framework of non-relativistic quantum field theory. This approach describes the dynamics of these quantum particles and their interactions, by accentuation of their different performances as coherent or incoherent waves. The achieved results strongly depend from the preconditions: whether the fluctuating forces are turned on or turned off. With the inset of fluctuations, the quantum coherence is destroyed, and only incoherent particle solutions are obeyed. Without the impact of fluctuations wave solutions dominate. Another type of wave solution are coherent wave packets which are counter-running, where their superposition can extinct or enhance them. This kind of interfering coherent solutions is applied on the polymerization of protofilaments. The calculations of this contribution demonstrate that the quantum coherence can be only observed when fluctuations are excluded. The conclusion is that that dedicated biological processes must be able to suppress the destroying influences of the local environment. In contrary to technical-based experiments, where coherence is only obtained when the fluctuations are deliberately excluded (e.g. quantum computer). Therefore, the answer why the processes of quantum biology can generate quantum coherence at least in case of microtubules is actually not answered. Kinesins in combination with microtubules are fundamental for cellular functions and morphogenesis. Recent genetic experiments uncovered their role for tumor suppression and developmental patterning. However, these findings which open exciting new areas of kinesin research are not included in this contribution, because the description of the kinesin-microtubule system is to comprehensive for one article.

Vibration Control of Tie Rod Rotors With Optimization of Unbalanced Force and Unbalanced Moment

This paper proposes a method for optimizing unbalanced force and unbalanced moment of the multistage disk based on sequence quadratic program algorithm to solve the vibration problem of gas turbine tie rod rotor. This method guides the assembly phase of the multistage disks. The influence of unbalanced force and unbalanced moment on the vibration of the tie rod rotor are analyzed based on the characteristics of rotor structure and assembly process. A dynamic model of the unbalanced force and unbalanced moment of the tie rod rotor is established. The sequence quadratic program algorithm is used to optimize multi-dimension of unbalanced force and moment, so the global optimal solution can be obtained. In order to verify the effectiveness of the optimization method proposed in this paper, vibration control experiments are carried out for traditional tie rod rotor and gas turbine tie rod rotor structure. The results show that both unbalanced force optimization and unbalanced moment optimization can control the tie rod rotor vibration effectively, and unbalanced moment optimization is better. Unbalanced moment optimization is used to perform constant speed and speed-up experiment on the gas turbine tie rod rotor structure. At 1200r/min, the maximum vibration reduction of the system is 76.68%. And the vibration has a decrease of 43.3% at the first-order critical speed. The proposed method in this paper can be used not only for the guidance of tie rod rotor assembly of gas turbine, but also for the vibration control during operation.

Implementing Large-Scale Aerospace Assembly 4.0 Demonstration Systems

The Future Automated Aerospace Assembly phase 1 technology Demonstrator (FA3D) was commissioned at the University of Nottingham and used to demonstrate concepts from the EPSRC Evolvable Assembly Systems project in specific industrial use cases. A number of lessons were learned from the specification, procurement, commissioning, and use of the cell. These lessons have been applied to the specification of Phase 2 of the Future Automated Aerospace Assembly Demonstrator (FA3D2) — currently in development — that will translate the Evolvable Assembly Systems research to a higher technology readiness level and address the challenges of scalable and transformable manufacturing systems. The FA3D2 will act as a showcase national experimental testbed and technology demonstrator in digital- and informatics-enabled aerospace manufacturing technologies, and the project itself will generate knowledge, skills, and experience in the delivery of such systems for academia and industry. After summarising the Evolvable Assembly Systems project, this paper presents details of the technologies demonstrated through the FA3D, and how this experience has been used to develop a novel approach to specifying the FA3D2.

On the Gas Content, Star Formation Efficiency, and Environmental Quenching of Massive Galaxies in Protoclusters at z ≈ 2.0–2.5

We present ALMA Band 6 (nu=233GHz, lambda=1.3mm) continuum observations towards 68 'normal' star-forming galaxies within two Coma-like progenitor structures at z=2.10 and 2.47, from which ISM masses are derived, providing the largest census of molecular gas mass in overdense environments at these redshifts. Our sample comprises galaxies with a stellar mass range of 1x10^9M_sun - 4x10^11M_sun with a mean M_*~6x10^10M_sun. Combining these measurements with multiwavelength observations and SED modeling, we characterize the gas mass fraction and the star formation efficiency, and infer the impact of the environment on galaxies' evolution. Most of our detected galaxies (~70%) have star formation efficiencies and gas fractions similar to those found for coeval field galaxies and in agreement with the field scaling relations. However, we do find that the proto-clusters contain an increased fraction of massive, gas-poor galaxies, with low gas fractions (f_gas<6-10%) and red rest-frame ultraviolet/optical colors typical of post-starburst and passive galaxies. The relatively high abundance of passive galaxies suggests an accelerated evolution of massive galaxies in proto-cluster environments. The large fraction of quenched galaxies in these overdense structures also implies that environmental quenching takes place during the early phases of cluster assembly, even before virialization. From our data, we derive a quenching efficiency of E_q~0.45 and an upper limit on the quenching timescale of T_q<1Gyr.

Discovery of a galaxy overdensity around a powerful, heavily obscured FRII radio galaxy atz= 1.7: star formation promoted by large-scale AGN feedback?

We report the discovery of a galaxy overdensity around a Compton-thick Fanaroff–Riley type II (FRII) radio galaxy atz = 1.7 in the deep multiband survey around thez = 6.3 quasi-stellar object (QSO) SDSS J1030+0524. Based on a 6 h VLT/MUSE and on a 4 h LBT/LUCI observation, we identify at least eight galaxy members in this structure with spectroscopic redshiftz = 1.687 − 1.699, including the FRII galaxy atz = 1.699. Most members are distributed within 400 kpc from the FRII core. Nonetheless, the whole structure is likely much more extended, as one of the members was serendipitously found at ∼800 kpc projected separation. The classic radio structure of the FRII itself extends for ∼600 kpc across the sky. Most of the identified overdensity members are blue, compact galaxies that are actively forming stars at rates of ∼8–60M⊙yr−1. For the brightest of them, a half-light radius of 2.2 ± 0.8 kpc at 8000 Å rest-frame was determined based on adaptive optics-assisted observations with LBT/SOUL in the Ks band. We do not observe any strong galaxy morphological segregation or concentration around the FRII core. This suggests that the structure is far from being virialized and likely constitutes the progenitor of a local massive galaxy group or cluster caught in its main assembly phase. Based on a 500 ksChandraACIS-I observation, we found that the FRII nucleus hosts a luminous QSO (L2 − 10 keV = 1.3 × 1044erg s−1, intrinsic and rest-frame) that is obscured by Compton-thick absorption (NH = 1.5 ± 0.6 × 1024cm−2). Under standard bolometric corrections, the total measured radiative power (Lrad ∼ 4 × 1045erg s−1) is similar to the jet kinetic power that we estimated from radio observations at 150 MHz (Pkin = 6.3 × 1045erg s−1), in agreement with what is observed in powerful jetted AGN. OurChandraobservation is the deepest so far for a distant FRII within a galaxy overdensity. It revealed significant diffuse X-ray emission within the region that is covered by the overdensity. In particular, X-ray emission extending for ∼240 kpc is found around the eastern lobe of the FRII. Four out of the six MUSE star-forming galaxies in the overdensity are distributed in an arc-like shape at the edge of this diffuse X-ray emission. These objects are concentrated within 200 kpc in the plane of the sky and within 450 kpc in radial separation. Three of them are even more concentrated and fall within 60 kpc in both transverse and radial distance. The probability of observing four out of the sixz = 1.7 sources by chance at the edge of the diffuse emission is negligible. In addition, these four galaxies have the highest specific star formation rates of the MUSE galaxies in the overdensity and lie above the main sequence of field galaxies of equal stellar mass atz = 1.7. We propose that the diffuse X-rays originate from an expanding bubble of gas that is shock heated by the FRII jet, and that star formation is promoted by the compression of the cold interstellar medium of the galaxies around the bubble, which may be remarkable evidence of positive AGN feedback on cosmological scales. We emphasize that our conclusions about the feedback are robust because even assuming that the diffuse X-ray emission arises from inverse Compton scattering of photons of the cosmic microwave background by the relativistic electrons in the radio lobe, star formation may be promoted by the nonthermal pressure of the expanding lobe.

Product Segmentation and Sustainability in Customized Assembly with Respect to the Basic Elements of Industry 4.0

Sustainable manufacturing is not just about manufacturing, but also products and services. In the area of custom production processes, there may also be circumstances of organizational management where compliance with labor productivity and the due-date principle is problematic. Similar products with different operating times cause the throughput of assembly lines to slow down, increase number of works in progress (WIP), and increase productivity waste. It is possible to reduce this impact through various productivity-enhancing methods and innovations. This paper presents an innovative approach to product segmentation in the assembly phase of custom manufacturing, and a proposal for a new segmentation procedure that will allow significantly better integration of products into existing assembly processes without negatively impacting the company’s production indicators. The scientific problem was defined on the basis that extending existing segmentation by the third dimension of operating times allows products in MTO (made to order) environments to be divided into families with approximately equal operating times. This will increase assembly efficiency in existing medium to large companies without large investments in the development and adaptation of assembly process products. The contributions of this work relate mainly to simple adaptations to existing processes in medium-sized businesses. The proposed solution respects the basic elements of Industry 4.0.

Characteristics of hydrocarbon transport systems and migration in slope areas of Qikou Sag, Bohai Bay Basin

The transport system plays an important role in hydrocarbon accumulation in slope area. The geochemical characteristics of the reservoir indicate that the oil and gas in this area generally have the tendency of migration and accumulation from the hydrocarbon generation center to the high part of slope. According to the relationship between source kitchens and traps, the hydrocarbon migration is divided into three types: inside source accumulation, near source vertical migration and outside source accumulation, controlled by the differential pressure between source rock and reservoir, dominant pathway-cap assembly and dominant migration phase respectively. The main types of migration pathway in the slope area are sand bodies, faults and unconformities, and the matching relationship between them controlled the direction and mode of oil and gas migration and accumulation in the slope area. The hydrocarbon migration and accumulation of middle-shallow layer in the low-middle slope are controlled by the dominant pathways and the matching relationship between faults and cap rocks, the hydrocarbon migration and accumulation in the middle slope are controlled by the favorable sedimentary facies, and the hydrocarbon migration and accumulation in the high slope are controlled by the distribution of sand bodies and favorable structures.

Design and Development of Stirring and Cooking Machines for Palm sugar

The production process of palm sugar is carried out by farmers or craftsmen with very simple equipment, namely cauldrons, stirrers and firewood stoves. Products was produced using this method are not good, short durability, require a long time, so it is inefficient and effective. The purpose of this study was to overcome worker fatigue, minimize work accidents and increase the production capacity of printed palm sugar and palm sugar. The research method that will be carried out is designing and making a stirrer and cooking machine for palm sugar palm, an electric motor drive system with several stages, namely the preparation stage in the form of a field survey of the conditions and production capacity of palm sugar, and preparation of materials and equipment required, the assembly phase of equipment components that have been made or purchased, and the Testing phase of the assembled equipment are tested. This testing phase will be repeated over and over until the data about the correct rotation is obtained to get the optimal amount of production. Specifications of the stirrer and cooking sugar ants are 155 cm high, 80 cm long, and 65 cm wide, stirring shaft diameter 1 inch and the power of the motor drive 1/2 hp, and a capacity of 29 kg per day.

Microtubule minus-end stability is dictated by the tubulin off-rate.

Dynamic organization of microtubule minus ends is vital for the formation and maintenance of acentrosomal microtubule arrays. In vitro, both microtubule ends switch between phases of assembly and disassembly, a behavior called dynamic instability. Although minus ends grow slower, their lifetimes are similar to those of plus ends. The mechanisms underlying these distinct dynamics remain unknown. Here, we use an in vitro reconstitution approach to investigate minus-end dynamics. We find that minus-end lifetimes are not defined by the mean size of the protective GTP-tubulin cap. Rather, we conclude that the distinct tubulin off-rate is the primary determinant of the difference between plus- and minus-end dynamics. Further, our results show that the minus-end-directed kinesin-14 HSET/KIFC1 suppresses tubulin off-rate to specifically suppress minus-end catastrophe. HSET maintains its protective minus-end activity even when challenged by a known microtubule depolymerase, kinesin-13 MCAK. Our results provide novel insight into the mechanisms of minus-end dynamics, essential for our understanding of microtubule minus-end regulation in cells.

Shape Adjustment of Flexible Rib for Large Deployable Reflector

The surface of large deployable reflectors has to be carefully adjusted to achieve the required accuracy, which is an effective way to compensate for manufacturing and assembly errors or other imperfections. An accurate mechanical model is essential for all shape-adjustment methods. The shape adjustment of large deployable reflectors based on the reconstruction, finite, genetic, and tension (RFGT) method is addressed in the assembly phase. The RFGT method includes reverse reconstruction, finite element method, genetic algorithm, and tension adjustment. Combined with the method of subarea photography and splicing, a digital photogrammetry system is used to test the reflector surface. Interpolation is used for curve fitting, and the flexible rib is accurately modeled through reverse reconstruction. The finite element method is used to analyze the deformation regularity of the rib under the stress load of each rope. The relationship between the node shape accuracy for the rib lower edge and the rope stress loads is established. The optimal combination of rope stress loads is obtained using a genetic algorithm. The ropes apply extra tension loads to adjust the shape of the rib based on the original tension. The surface test data show that the rib lower edge is optimized after multiple adjustments in the assembly phase.

Lean IHOP Transformation of Shipyard Erection Block Construction

The modern system of shipbuilding includes applying integrated hull construction, outfitting, and painting (IHOP) of ship interim products, as opposed to the traditional manner of first constructing the hull blocks, then performing basic outfitting and finally painting, all separate of each other. Even though most shipyards apply some degree of integration of all trades during vessel construction, much work could still be better integrated. This article analyzes and maps the present IHOP construction of a typical shipbuilding erection block in a real shipyard. Through the application of a product work breakdown structure and group technology, the degree of IHOP integration could be increased. This is demonstrated to be in compliance with the lean principles of improving flow and kaizen. The article will suggest how the vessel construction could be become leaner through a value stream map, thereby decreasing both duration time and man-hours, thus securing significant savings for the shipyard. 1. Introduction The concept of integrated hull construction, outfitting, and painting (IHOP) of ship blocks has existed for the past 40 years. However, the level of IHOP application differs among shipyards. There is still much rework and outfitting that is performed on the slipway or in the dry-dock as opposed to during the assembly or preerection construction phase. The main aim of IHOP is to construct and outfit and paint ship blocks to a high degree while minimizing the outfitting tasks for later construction stages. This method greatly reduces shipbuilding production man-hours which yields major savings for shipyards. The idea of IHOP derives from group technology. In the distant past, ships were built in the classic method with keel laying on the slipway followed by piecemeal steel construction with outfitting of ship equipment afterward. Outfitting includes all equipment that is not an integral part of the hull structure such as equipment foundations, pipes, cables, hangars, ladders, pumps, valves, boilers, purifiers, evaporators, bus and switchboards, diesel generator sets, the main engine, and all of the ship systems including the wheelhouse electronics and navigation equipment.

Effects of hybrid steel fiber reinforced composites on structural performance of segmental linings subjected to TBM jacks

AbstractIn recent years, incorporating fibers as the main reinforcement in segmental lined tunnels has gained significant interest. Damage to segmental linings due to the thrust force of TBM jacks is one of the main problems that arises in the assembly phase, reducing serviceability and durability of tunnels. The aim of this paper is to experimentally and numerically investigate the effects of fiber size, content, and hybridization on the performance of steel fiber reinforced concrete (SFRC) tunnel segments under TBM jack forces compared to conventionally reinforced concrete (RC) segments. In this regard, different scenarios of segment support conditions and eccentricity of the applied TBM jack loads are investigated in a particular real tunnel. The results showed that under various configurations of segment support and load eccentricity, SFRC composites show better performance over RC in both SLS and ULS conditions under TBM jack loads in terms of cracking strength and damage propagation.

From natural language text to rules: knowledge acquisition from formal documents for aircraft assembly

Knowledge acquisition is a well-acknowledged bottleneck in the building of knowledge-based systems. Documents are a useful source of knowledge from experts. This paper targets the reuse of knowledge from the assembly phase of a product in the design and planning phases. Issues, their causes and the parameters involved are necessary to be acquired for reusing the knowledge so acquired. This paper discusses a method for knowledge acquisition, as a pipeline of existing tools in natural language understanding and processing. The acquired knowledge is expected to help in the decision making for a smart manufacturing system. The process of knowledge acquisition involves recognising the presence of issues and their causes using a combination of sentiment analysis and text patterns. The causes are then dissected to identify the constraints and constituent parameters. These pieces of knowledge are then reconstructed to form rules in a knowledge base. This paper demonstrates progress towards realising the method, by developing the cause dissection and rule-writing components, and validation of the issue-cause acquisition component with human subjects. A discussion is then presented on the potential integration and validation of the overall knowledge acquisition pipeline with a smart manufacturing system.

Conceptual Design for Assembly in Aerospace Industry: A Method to Assess Manufacturing and Assembly Aspects of Product Architectures

AbstractIn recent years, the air transport market has quickly grown, creating new civil aircrafts demand, challenging the actual production rate of aerospace industries. The bottleneck of the current civil aircrafts production rate lies in the capability of the manufacturing and assembly facilities in relation to the aircrafts architecture design.The aim of this work is to develop a methodology and a related mathematical model that can be used at the conceptual design phase for the assessment of criticalities related to the product assemblability. The methodology allows to recognize modules and/or interfaces which are mostly affecting the assembly time providing a design tool for the comparison and evaluation of product architecture alternatives.A preliminary application has been done on the nose-fuselage of a civil aircraft for passenger transport. The test case provides interesting outcome in the identification of modules and module interfaces which are strongly affecting the assembly phase and required a re-arrangement (new architecture design) for the process improvement.