Assembly Attachment Research Articles

Development of a System for Materials Science Studies on the T-15MD Tokamak

One of the main objectives pursued in carrying out materials science studies on the T-15MD tokamak is to insert samples, including large-scale ones, both for their long-term life cycle tests in the near-wall plasma areas and for studying the effect of impulse loads in the divertor section. A conceptual design of a system for carrying out materials science studies on the T-15MD tokamak has been developed at the Department of General Physics and Nuclear Fusion of the National Research University Moscow Power Engineering Institute. The system will open the possibility to carry out unique experiments on studying the state and composition of the divertor and first wall surfaces without the need to disturb the tokamak chamber vacuum and dismantle the components. It will be possible to perform such studies in the time intervals between tokamak pulses, which will make it possible to reveal changes on the divertor surface after each pulse and estimate correlations between the plasma parameters and changes on the first wall surface. In the attachment assembly, means are provided for cooling the mockups with both water flow and dispersed water-air flow. In addition, various diagnostic devices for monitoring the first wall and divertor surfaces can be installed on the attachment assembly.

Controllable synthesis, characterization and photoluminescence properties of flower-like BaMoO4 hierarchical architectures

Flower-like BaMoO4 hierarchical architectures were prepared by a facile solvothermal method. A nucleation–oriented attachment–assembly–Ostwald ripening mechanism is presented for the formation of the BaMoO4 samples.

Investigation of dynamics of roll forming processes

This article contains the analysis of tube expander dynamics in complex interaction of structural elements of heat-exchange tubes attachment assembly in the process of roll-forming operation, description of dynamic process theoretical aspect. It is shown that torque variations lead to velocity fluctuations and influence the service life of operative parts of tube expander and quality of tube attachment assemblies.

Design for Reliability Analysis of Vibration-Induced Failures due to Equipment Assembly Bending Load and Vibration Responses

Abstract The oil and gas industry subsurface formation evaluation instruments experience significant challenging vibrations and shock levels. Equipment development requirements for these instruments include reliability and durability under these severe operating conditions. The engineering design for this equipment utilizes tools that enable the estimation of service lifetime, maintenance cycles, and related costs. These engineering tools model failure modes and their acceleration factors and how failures interact under certain circumstances. Laboratory test data and operations failure history are used to validate the model results. Incorporating equipment operational failure history into the reliability design after failure analysis, enables determination of failure modes and the length of stress level exposure. Before the equipment is commissioned to field operational service, it is subjected to a batch of environmental qualification tests under objective pass-fail criteria. The environmental qualificat...

Examining Potential Active Tempering of Adhesive Curing by Marine Mussels.

Mussels generate adhesives for staying in place when faced with waves and turbulence of the intertidal zone. Their byssal attachment assembly consists of adhesive plaques connected to the animal by threads. We have noticed that, every now and then, the animals tug on their plaque and threads. This observation had us wondering if the mussels temper or otherwise control catechol chemistry within the byssus in order to manage mechanical properties of the materials. Here, we carried out a study in which the adhesion properties of mussel plaques were compared when left attached to the animals versus detached and exposed only to an aquarium environment. For the most part, detachment from the animal had almost no influence on the mechanical properties on low-energy surfaces. There was a slight, yet significant difference observed with attached versus detached adhesive properties on high energy surfaces. There were significant differences in the area of adhesive deposited by the mussels on a low- versus a high-energy surface. Mussel adhesive plaques appear to be unlike, for example, spider silk, for which pulling on the material is needed for assembly of proteinaceous fibers to manage properties.

From Single Pt Atoms to Pt Nanocrystals: Photoreduction of Pt2+ Inside of a PAMAM Dendrimer

The dynamics of structural transformations of Pt aggregates in the “quantum size” range where their molecular structure transforms into crystalline nanoparticles with metallic properties is an important issue in nanoscience. Here, we show high-resolution transmission electron microscopy (HRTEM) and spectroscopic observations of the polyamidoamine (PAMAM) dendrimer-mediated system, Pt–PAMAM, after UV irradiation that reveal the formation of small Ptδ+n clusters (n = 2–8) with linear chains of −Pt–Pt–, which are the building blocks of stable nanocrystals. Dynamic imaging in an aberration corrected TEM at atomic resolution shows intermediate molecular and crystalline states and coalescence of Pt clusters into stable nanocrystals via an oriented attachment assembly process. We propose that the structural transformation from Pt aggregates to nanocrystals occurs between 1.5 and 2 nm and that a phase transition of the type “disordered-to-crystalline” exists depending on the number of atoms in the cluster.

Residual Strain Measurement of Thin-Layer Cured Adhesives and Their Effects on Warpage in Electronic Packaging

Residual strains (stresses) of thin-layer adhesives are important and need be determined and further analyzed for better reliability design of the joints or bump joints in electronic or optoelectronic packaging. The purposes of this paper are to quantify residual strains of two adhesives: A (paste type) and B (film type) due to chemical shrinkage, stress relaxation, and thermal-loadings and moisture-loadings, and to investigate their effects on the warpage of die attachment assembly. At the beginning, the mechanical properties of the two adhesives in terms of temperatures are measured by dynamic mechanical analyzer (DMA) and thermomechanical analyzer (TMA). The residual strains are documented by testing fully cured adhesive/silicon bi-material plates under thermal and moisture loading using Twyman-Green (T/G) interferometry system associated with Timoshenko's bi-material theory and finite element method (FEM). Furthermore, the warpage of silicon/adhesive/Cu tri-material plates (similar to die attachment assembly) with both adhesives under thermal and moisture loading are also investigated by T/G experiments and confirmed by Suhir's solution and FEM results. For adhesive-A, the results of the bi-material plate suggest that the residual strains are only induced by mismatch of the coefficients of thermal expansion during thermal loading, rather than other factors, right after the fully cured adhesive cooling down to room temperature. On the other hand, for adhesive-B, it was found that the additional residual strain of this film adhesive caused by chemical shrinkage plus stress relaxation, is about 2.26 ? 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> , which accounts for 85% of thermal-residual strains in the bi-material plate from curing temperature cooling down to room temperature. Experimental results also indicated that moisture-absorption expansion of the both adhesives is the major cause of decreasing warpage for the bi-material plates at 29?C/55% RH, other than stress relaxation. In contrast to the results of the bi-material plate, the warpages of the tri-material plates are found to be insensitive to the moisture-absorption, chemical, and thermal strains of adhesives, but not to elastic moduli of adhesives, due to their relatively thin-layer and compliant nature. This paper has successfully laid down an approach for determining residual strain of thin-layer adhesive and provided information about their effect on warpage of die attachment assembly.

Use of coffee straw for overdenture bar fabrication

aProfessor, Department of Prosthodontics. bChair, Department of Prosthodontics; Dean, Educational Support Services. (J Prosthet Dent 2009;102:266) Bar attachments are most commonly used for enhancing the retention and support of a dental or maxillofacial prosthesis. A bar attachment assembly connects retained roots, teeth, or osseointegrated implants. Several bar attachment systems have been described in the dental literature.1-3 Among them, the Dolder bar (Dolder Bar System; Attachments Intl, Inc, Burlingame, Calif ) and the Hader bar (Hader-EDS Bar System; Attachments Intl, Inc) are most often used for overdentures and implantretained restorations. A disadvantage of these bar systems is that they are expensive.4 An economical replacement for the bar systems is described. The plastic coffee straw (stirrer) can be cast as a bar for splinting retained roots, copings on abutment teeth, or castable abutments for implants. Any straw which adapts well to the prefabricated metal housing and clip can be used. PROCEDURE

Recent In-Vessel Integration Concepts for a European DEMO Reactor

A part of the recent scoping studies for a European DEMO reactor deals with the design of the in-vessel components and their integration inside the reactor. The main in-vessel components are the Breeding Blankets (Helium Cooled Lithium Lead and Helium Cooled Pebble Bed), the helium supply units called Manifolds (MF) and the Neutron Shields. Alternative concepts for the integration of these components have been developed in parallel by different Europe an associations (FZK, CEA, and EFET). Nevertheless these concepts are all based on the vertical segmentation concept called “Multi Module Segment” (MMS). The big advantage of the MMS concept dwells in the fact that blankets and MF constitute a vertical non-permanent segment to be installed and dismantled by Remote Handling (RH) tools through the upper ports of the reactor. The dimensions, geometry and materials are strictly dependent on the harsh conditions of the in-vessel environment: high temperatures, high neutron fluxes, and high thermo-mechanical loads during normal operations and disruptive events. In addition, suitable systems of attachment able to withstand thermal expansion and the expected loads have been developed to provide reliability and easy in-vessel maintenance. The general aspects of the MMS system and the common RH procedures foreseen are presented and the different specific options for solving attachment and in-vessel assembly issues are discussed.

Comparison of torsional stability of 2 types of split crimpable surgical hooks with soldered brass surgical hooks

The purpose of this in-vitro study was to compare the torsional stability of split crimpable surgical hooks and soldered brass surgical hooks on a rectangular stabilizing archwire. Coated split crimpable hooks (Never-Slip Grip, TP Orthodontics, LaPorte, Ind), ribbed crimpable hooks (TP Orthodontics), and .032-in brass soldered hooks/notched electrodes (Ormco/Sybron Dental Specialties, Orange, Calif) were attached to a 0.019 x 0.025-in stainless steel archwire. The archwire/hook attachment assembly was secured into a dual contact jig and statically mounted to the base of a universal testing machine. The hooks were engaged by a wire loop attached to the upper load cell of the machine, which pulled the wire until the hook was torsionally displaced from the archwire. The mean forces, measured in newtons (N), required to dislodge the hooks were as follows: soldered brass surgical hooks (51.3 +/- 5.2 N), coated split crimpable hooks (49.9 +/- 6.6 N), and ribbed split crimpable hooks (31.3 +/- 5.4 N). Data were analyzed with 1-way ANOVA and Tukey HSD post-hoc tests at alpha = .05. Ribbed split crimpable hooks provided significantly less resistance to torsional displacement than the other types of hooks (P <001). There was no difference between coated split crimpable hooks and soldered brass surgical hooks (P >05). Under the conditions of this study, the results suggest that soldered brass surgical hooks and coated split crimpable hook attachments provide more stability to torsional dislodgement from a rectangular stabilizing archwire than ribbed split crimpable hooks.

Neckless lap guitar

A neckless guitar including a guitar body forming a tear shaped acoustic chamber. The guitar includes a peg head with at least one receiving slot for a tuning key. The peg head is directly attached to the top end of the acoustic chamber such that no neck-region is formed. The neckless guitar has a fret board, a saddle assembly and a nut assembly, at least one tuning key and at least one string that originates at the saddle assembly, passes over the fret board and through or over the nut assembly, and is connected to the tuning key. In one embodiment, the neckless guitar has an attachment assembly for removably connecting the guitar body and the peg head. The attachment assembly includes a peg head block positioned at the top end of the body. A gusset on the peg head couples the peg head block and the peg head.

Infrared spectrometer attachment assembly for use with vacuum and high-pressure cells

Abstract

C. elegans PAT-6/Actopaxin Plays a Critical Role in the Assembly of Integrin Adhesion Complexes In Vivo

Background: The novel focal adhesion protein actopaxin includes tandem unconventional calponin homology (CH) domains and a less well-conserved N-terminal stretch. Dominant-negative studies have implicated actopaxin in focal adhesion formation.Results: PAT-6/actopaxin, the sole actopaxin homolog in C. elegans, is located in body wall muscle attachments that are in vivo homologs of focal adhesions. We show using pat-6 protein null alleles that PAT-6/actopaxin has critical nonredundant roles during attachment maturation. It is required to recruit UNC-89 and myofilaments to newly forming attachments, and also to reposition the attachments so that they form the highly ordered array of dense body and M line attachments that are characteristic of mature muscle cells. PAT-6/actopaxin is not required for the deposition of UNC-52/perlecan in the basal lamina, nor for the initiation of attachment assembly, including the clustering of integrin into foci and the recruitment of attachment proteins PAT-4/ILK, UNC-112, and DEB-1/vinculin from the cytosol. PAT-6/actopaxin, PAT-4/ILK, and UNC-112 are each required for the same steps during attachment assembly in vivo, consistent with the notion that they work together in multiprotein complex. Supporting this idea, PAT-4/ILK can simultaneously bind to PAT-6/actopaxin and UNC-112, forming a ternary complex, in yeast three-hybrid assays. Finally, we show that both calponin homology domains are required for PAT-6/actopaxin's critical functions during attachment assembly in vivo.Conclusions: We show directly by loss-of-function genetics that PAT-6/actopaxin plays essential roles during the maturation of integrin-mediated muscle attachments in vivo.

Evolution of a unique flip-chip MCM-L package

Flip-chip (FC) packaging is gaining acceptance in the electronics packaging arena. More sources of bumped die and high density printed wiring boards (PWBs) laminates become available every day. Also, known good die (KGD) issues are being resolved by several companies, and design tools to perform FC packaging designs are becoming more available. This is the infrastructure FC packaging requires to become the packaging method of choice, particularly for >200 I/O applications. FC packages come in a variety of styles: FC plastic ball grid arrays (FC/PBGAs), FC plastic quad flat packs (PC/PQFPs), etc. Presently, the industry's drive is toward single chip packages on low cost laminates; i.e., organic substrates. Work is starting to occur in the area of multichip FC packages, due to the need to increase memory to microprocessor speed communication. In this article, a unique FC/MCM-L package is discussed. Part I will concentrate on the development and reliability testing of a one to four chip leadless FC/MCM-L package. Unlike traditional surface mount (SM) components that are attached to printed wiring boards (PWBs) with leads, the SM pads within the body of the package are used for attachment to a PWB. Collapsible eutectic solder domes are deposited on the SM pads by traditional screen printing. After reflow, these domes are used to connect the FC/MCM-L to the PWB. Challenges encountered during package design, PWB fabrication and first and second level assembly will be discussed. Part II of this article will focus on the extension of this FC/MCM-L package to a BGA second level interconnect. Change of FC attachment method, design enhancements, assembly, and reliability testing results will be presented.

Integral attachment using snap‐fit features: a key to assembly automation. Part 5 ‐ a procedure to constrain parts fully and generate alternative attachment concepts

This fifth part of a comprehensive six‐part series of articles presents a systematic procedure for formalising the generation of alternative concepts for a particular design employing integral snap‐fit attachments. With the procedure, the alternatives generated are representative of the entire pertinent design space, since they include alternative attachment interface geometries, assembly procedures, attachment features, and constraint options for a particular application. The procedure is easy to use, effective and efficient, and results in a number of alternatives which are sufficient to represent the entire pertinent design space, but not so large as to preclude selection of a best concept using an optimisation method.

Study of thermal deformation of microelectronics packaging product by interferometric technique

In this paper, the out-of-plane deformation of silicon surface of Direct Chip Attachment (DCA) assembly, under thermal loading, was measured in real-time by Twyman/Green interferometry. The contour maps of the out-of-plane displacement fields of silicon surface under thermal loading and cycling of various temperature were obtained. Experimental results show that the relation between the out-of-plane displacement and temperature is nonlinear and varies with temperature cycling, due to nonlinear mechanical behavior of the materials used in electronic packaging. A comparison of the out-of-plane displacement fields of silicon surface measured by T/G interferometry in real-time and replicating technique of high temperature specimen grating of moire interferometry was made.

Modifications of the superstructure for the staple implant

Two techniques have been described to expedite fabrication and reduce the cost of prostheses made for staple implants. The techniques permit placement of a simulated transosseous pin within the master cast. At the time of denture placement in technique No. 1, the coping-bar attachment assembly is cemented (Fig. 12). In technique No. 2 the superstructure is placed over the transosteal pins and secured between the locknuts to maintain the base of the lower locknut 1.5 mm from the crest of the alveolar ridge (Fig. 13). Technique No. 2 permits removal of the superstructure as desired. Patients should be instructed in proper oral hygiene and denture care.

Attachment assembly for testing group time-lag meters in the video frequency range

Attachment assembly for testing group time-lag meters in the video frequency range