Effect Of Connection Type Research Articles

Strengthening of glass fiber sheets for multi-bolted pultruded GFRP connections: Effects of connection type and bolt-tightening force

This study investigated the effects of bolt-tightening forces on the connection strengths of non-strengthened and glass fiber sheet (GFS)-strengthened pultruded glass fiber reinforced polymer (PGFRP) connections through a series of experiments using double-lap and single-lap specimens. A total of 96 specimens (3 specimens for each parameter), half of which were non-strengthened, were tested under tensile loads and four bolt-tightening forces: 0, 5 N.m, 10 N.m, and 20 N.m. The (0°/90°)/chopped strand mat/(0°/90°) lamination was bonded to both PGFRP plates’ outside surfaces and improved the connection strengths. The results indicated that maximum failure loads increased with an increase in bolt-tightening forces. However, there were different trends in the maximum failure load changes, depending on the specimen type (non-strengthened or GFS-strengthened specimens; double-lap or single-lap specimens) and bolt-tightening forces. In addition, GFSs could effectively improve PGFRP’s connection strengths and ductility performances.

A technique for splinting implant impression posts by using nylon sutures

Recording the precise 3-dimensional intraoral implant location and transferring it to a definitive cast is an important clinical step during implant prosthesis fabrication. 1 Kim J.H. Kim K.R. Kim S. Critical appraisal of implant impression accuracies: a systematic review. J Prosthet Dent. 2015; 114: 185-192 Abstract Full Text Full Text PDF PubMed Scopus (31) Google Scholar Multiple implant impression posts are typically splinted to minimize movement during removal of the impression from the mouth and during attachment of the laboratory analogs to the impression posts. 2 Papaspyridakos P. Lal K. White G.S. Weber H.P. Gallucci G.O. Effect of splinted and nonsplinted impression techniques on the accuracy of fit of fixed implant prostheses in edentulous patients: a comparative study. Int J Oral Maxillofac Implants. 2011; 26: 1267-1272 PubMed Google Scholar , 3 Papaspyridakos P. Hirayama H. Chen C.J. Ho C.H. Chronopoulos V. Weber H.P. Full-arch implant fixed prostheses: a comparative study on the effect of connection type and impression technique on accuracy of fit. Clin Oral Implants Res. 2016; 27: 1099-1105 Crossref PubMed Scopus (25) Google Scholar , 4 Filho H.G. Mazaro J.V. Vedovatto E. Assunção W.G. dos Santos P.H. Accuracy of impression techniques for implants. Part 2 - comparison of splinting techniques. J Prosthodont. 2009; 18: 172-176 Crossref PubMed Scopus (33) Google Scholar , 5 Baig M.R. Accuracy of impressions of multiple implants in the edentulous arch: a systematic review. Int J Oral Maxillofac Implants. 2014; 29: 869-880 Crossref PubMed Scopus (30) Google Scholar , 6 Lee H. So J.S. Hochstedler J.L. Ercoli C. The accuracy of implant impressions: a systematic review. J Prosthet Dent. 2008; 100: 285-291 Abstract Full Text Full Text PDF PubMed Scopus (234) Google Scholar

Effects of an Allostatic Closed-Loop Neurotechnology (HIRREM) on Brain Functional Connectivity Laterality in Military-Related Traumatic Stress.

ABSTRACTBACKGROUND AND PURPOSEBrain asymmetries are reported in posttraumatic stress disorder, but many aspects of laterality and traumatic stress remain underexplored. This study explores lateralization changes in resting state brain network functional connectivity in a cohort with symptoms of military‐related traumatic stress, associated with use of a closed‐loop neurotechnology, HIRREM.METHODSEighteen participants (17 males, mean age 41 years [SD = 7]) received 19.5 (1.1) HIRREM sessions over 12 days. Whole brain resting magnetic resonance imaging was done pre‐ and post‐HIRREM. Laterality of functional connectivity was assessed on a whole brain basis, and in six predefined networks or regions. Laterality of connectivity within networks or regions was assessed separately from laterality of connections between networks or regions.RESULTSBefore HIRREM, significant laterality effects of connection type (ipsilateral for either side, or contralateral in either direction) were observed for the whole brain, within networks or regions, and between networks or regions. Post‐HIRREM, there were significant changes for within‐network or within‐region analysis in the motor network, and changes for between‐network or between‐region analyses for the salience network and the motor cortex.CONCLUSIONSAmong military service members and Veterans with symptoms of traumatic stress, asymmetries of network and brain region connectivity patterns were identified prior to usage of HIRREM. A variety of changes in lateralized patterns of brain connectivity were identified postintervention. These laterality findings may inform future studies of brain connectivity in traumatic stress disorders, with potential to point to mechanisms of action for successful intervention.

Biological Responses to the Transitional Area of Dental Implants: Material- and Structure-Dependent Responses of Peri-Implant Tissue to Abutments.

The stability of peri-implant tissue is essential for the long-term success of dental implants. Although various types of implant connections are used, little is known about the effects of the physical mechanisms of dental implants on the stability of peri-implant tissue. This review summarizes the relevant literature to establish guidelines regarding the effects of connection type between abutments and implants in soft and hard tissues. Soft tissue seals can affect soft tissue around implants. In external connections, micromobility between the abutment and the hex component of the implant, resulting from machining tolerance, can destroy the soft tissue seal, potentially leading to microbial invasion. Internal friction connection implants induce strain on the surrounding bone via implant wall expansion that translates into masticatory force. This strain is advantageous because it increases the amount and quality of peri-implant bone. The comparison of internal and external connections, the two most commonly used connection types, reveals that internal friction has a positive influence on both soft and hard tissues.

Resting-State Functional Connectivity in Neurosurgical Patients Under Propofol Anesthesia: Detectability and Variability Between Patients and Between Sessions

Intraoperative assessment of functional connectivity (FC) provides a new possibility for mapping the eloquent brain region before, during, and after tumor resection. The aim of this study was to perform a systematic analysis of detectability of FC and its variation between subjects and sessions. FC was analyzed in 10 patients with pituitary adenoma under propofol anesthesia before and after tumor resection. FC of each session (20 sessions total) was correlated to a reference matrix of a group of healthy subjects to evaluate variations of overall, interhemispheric, and intrahemispheric FC between sessions. Resting-state patterns could be detected during anesthesia (F1,9= 112.14, P < 0.001). There was a significant effect of session (F1,9= 19.401, P= 0.002), which included a reduction in resting state from the first to second session. There was no effect of connection type (F2,8= 1.498, P= 0.280), and there was no interaction between connection type and session (F2,8= 0.187, P=0.833). The correlation between the observed reduction in resting-state activity between the sessions and the time span between sessions was not significant (r= 0.25, P= 0.29). FC of the first session showed a significant correlation to the initial dose of anesthesia (r= 0.7, P=0.007). However, there was no significant correlation between the total dose of propofol and FC of the second session (r= 1.7, P= 0.6). Significant FC could be detected under anesthesia but showed a significant decrease in the second session. To implement FC intraoperative brain mapping, further studies are required to optimize the depth sedation to obtain stable FC between sessions.

Performance-Based Evaluation of a Double-Deck Tunnel and Design Optimization

The double-deck tunnel is well known as smart infrastructure because multiple sections can be used for various purposes. Although the stability of a double-deck tunnel is mainly governed by the intermediate slab, the effect of various governing factors on tunnel structural stability has not been fully investigated. In this study, performance-based evaluation method for a double-deck tunnel is suggested as a three-dimensional matrix considering the life cycle of a double-deck tunnel. Moreover, a customized software for design and maintenance of a double-deck tunnel is developed. A structural analysis solver based on a beam–spring model for a double-deck tunnel was embedded in this code. The effects of connection type as well as depth of tunnel, ground stiffness and traffic load on structural behavior of tunnel were investigated. From the analysis, it was found that the connection type between segment lining and intermediate slab significantly affects the behavior of segment lining: simply connected condition causes lesser stress and moment than fully fixed condition. The deeper the tunnel depth, the greater the member force of segment lining. In addition, as both the tunnel depth and the ground stiffness increase, the influence of connection type on the structural stability of the double-deck tunnel becomes insignificant.

Effects of Connection Type between Surface Vessel and Submersible Propeller on Motion Performance of Wave Glider

Wave Glider is an autonomous surface vehicle that directly uses wave energy to generate forward power and has been widely used in marine survey and observation. Wave Glider is composed of surface vessel, submersible propeller and the connection structure between them. Connection types are thought to be related to the performance of Wave Glider closely. In this paper, the effects of the connection structure between the surface vessel and the submersible propeller on the motion performance of the Wave Glider are studied. Several connection types such as rigid rod, cable, multi-link chain and elastic rod are applied to connect the surface vessel and the submersible propeller. The models of connection structures are developed respectively. Among them, cable model is established with a finite number of small cylinders, which connected by spring and damping elements; multi-link chain can be seen as hinged by multiple rigid rods; elastic rod model can be looked on as several segments linked with elastic components. Considering the connection characteristics, the integrated dynamic models are established by applying multi-body dynamics software ADAMS (Automatic Dynamic Analysis of Mechanical Systems) with consideration of the hydrodynamic forces on different components of Wave Glider. The propulsion performance of the Wave Glider is calculated by using numerical method, and the simulation results showed that the difference of propulsion performance with different connection types of the Wave Glider is slightly. But serious impacts can occur on the connections of rigid rod and multi-link chain. They can lead to serious extra load on the structure of Wave Glider. From the engineering practice of Wave Glider application, the cable connection is more convenient to transport, deploy, recover and store. It is also the generous connection type for wave glider.

Period Calculation of Thin Steel Plate Shear Walls and the Effect of Connection Type and Degree of Opening on it

Since four decades ago, Steel plate shear wall-SPSW- is a new system resistant to against lateral loads, which has attracted the attention of researchers and designers because of its numerous advantages. The behavior coefficient which has direct dependence on the reflection coefficient is in one way or another based on the period or the natural period of vibration of the resistant system, and considering the short life of this system, there has been no serious study on its period, and in ASCE 7 code, this system has been referred to other systems. In this study, the natural period of vibration of different frames and variant number of floors is examined for thin steel plate shear wall, the results of linear and nonlinear analyses -are compared, and then empirical relationships are presented. Moreover, the effects of connection type and different openings on the period degree of this system were being examined. The results supported the appropriateness of the offered empirical relationship in ASCE 7 code for short and midframes of thin steel plate shear wall in ASCE 7 code; however, it seems that the empirical relationship of tall frames should be increased twice.

Effect of connection type on galvanic corrosion between lead and copper pipes

Pipe connectors can significantly influence galvanic corrosion between lead and copper pipes by distancing the lead from copper pipe, introducing a third metal, and forming crevices. In this study, the effects of distance, connector material, and crevices on galvanic corrosion were examined, and bench‐scale comparison testing of commercial connectors was conducted using real tap waters. Brass connectors were found to only slightly decrease (&lt; 25%) the galvanic current that sacrifices, or corrodes, lead pipe, with higher reductions for brasses with higher zinc content. Crevices in brass connectors contained water with extremely high levels of lead (up to 9.4 × 106 μg/L); in bench‐scale tests, crevices produced approximately four times more lead release to the water than did direct connections.

Determination of Reducing Coefficient Values of Semi-Rigid Frames Using Artificial Neural Network

Lateral rigidity is a great issue in the view of structural analysis in civil engineering applications such as production of buildings, bridges, dams and roads. Furthermore, the connection properties have a remarkable role on the lateral rigidity and the tendency of structures under service loads. In fact, there aren’t any structures with perfectly rigid connections between beams and columns. Therefore, all connections performed by construction process can be defined as semi-rigid as, especially connections in steel structures. The effect of connection type on the lateral rigidity values of structures can be determined by reducing coefficients decreasing lateral rigidity with a certain extent. In the scope of this study, connection flexibility is modeled by linear elastic rotational springs for semi-rigid frames. The reducing coefficients are determined by using a computer program. Results are compared to the values predicted by artificial neural network (ANN) analyses. A strong relationship was established between calculated and predicted values.