To get better EDFA performance, we have to improve the coupling efficiency of semiconductor laser diode(LD) and fiber optic; also, increase the LD¡¦s power to achieve. There are plenty of ways to have higher coupling efficiency out there. Some of them even can reach 90% or better coupling efficiency. However, because of light field property, high-power LD output will not be able to apply to high coupling efficiency structure. Therefore, using cascaded fiber can improve coupling efficiency and maintain its characteristic in high-power laser output environment. Cascaded fiber is connecting SMF and GIF together. Although cascaded fiber can increase high-power LD output of coupling efficiency, it has 5% to 10% of loss during manufacture because of the inspect error of melting surface. We use CCD to observe the cascaded fiber¡¦s melting surface. Then, we pair with special light source to do the examination. Thus, we can overcome the obstacle, do automatically manufacture of the cascaded fiber in a small area, and reduce the coupling loss of cascaded fiber.

An experimental program was performed for qualitative and quantitative comparison of the maximum tensile resistance of contact and non-contact lap spliced bars in reinforced concrete block masonry using double pullout and wall splice specimens. A total of 32 specimens were tested, consisting of an equal number of double pullout specimens and full-scale wall splice specimens. Both specimen types had the identical cross-section. Eight replicate specimens for each specimen type were constructed with both contact and non-contact lap splice arrangements. Grade 400 deformed reinforcing bars with a 300 mm lap splice length were provided in all specimens. The double pullout specimens were tested applying direct tension to the lapped reinforcing bars. The splice resistance and displacement were recorded during testing. All double pullout specimens with contact lap splices developed, as a minimum, the yield strength of the reinforcing bars and generally displayed evidence of a yield plateau. In contrast, the double pullout specimens with non-contact lap splices failed when only 46.1% of the theoretical yield strength of the reinforcing bars was recorded as the maximum splice resistance. The difference between the average value of the tensile resistance in the contact and non-contact spliced bars was identified as being statistically significant at the 95% confidence level. Wall splice specimens were tested under a four-point loading arrangement with the lapped bars located in the constant moment region. The applied load and specimen deflection were recorded until failure occurred. A numerical analysis was then performed to calculate the maximum resistance of the spliced bars. The specimens with contact lap splices developed the theoretical yield capacity of the reinforcing bars. In contrast, the wall splice specimens with non-contact lap splices developed an average tensile resistance of 78% of the theoretical yield capacity. The difference between the average tensile resistances of the lapped bars in the two splice arrangements was identified as being statistically significant at the 95% confidence level. On average, the contact and non-contact lap spliced bars in the double pullout specimens developed 8.47% and 41.2% less tensile resistance, respectively, as compared to the wall splice specimens with the identical splice arrangement. Both differences were identified as being statistically significant at the 95% confidence level. Bond loss between the reinforcing bars and the surrounding grout was identified as the failure mode for both the double pullout and wall splice specimens with contact lap splices. In contrast, bond loss at the masonry block/grout interface was observed along the non-contact lapped bars in both specimen types, as identified by visual observations upon removal of the face shell and the surrounding grout. Based on the test results of the wall splice specimens with non-contact lap splices, a correction factor of 1.5 is suggested when calculating the effective splice length for the non-contact splice arrangement as tested.

An experimental program was performed for qualitative and quantitative comparison of the maximum tensile resistance of contact and non-contact lap spliced bars in reinforced concrete block masonry using double pullout and wall splice specimens. A total of 32 specimens were tested, consisting of an equal number of double pullout specimens and full-scale wall splice specimens. Both specimen types had the identical cross-section. Eight replicate specimens for each specimen type were constructed with both contact and non-contact lap splice arrangements. Grade 400 deformed reinforcing bars with a 300 mm lap splice length were provided in all specimens. The double pullout specimens were tested applying direct tension to the lapped reinforcing bars. The splice resistance and displacement were recorded during testing. All double pullout specimens with contact lap splices developed, as a minimum, the yield strength of the reinforcing bars and generally displayed evidence of a yield plateau. In contrast, the double pullout specimens with non-contact lap splices failed when only 46.1% of the theoretical yield strength of the reinforcing bars was recorded as the maximum splice resistance. The difference between the average value of the tensile resistance in the contact and non-contact spliced bars was identified as being statistically significant at the 95% confidence level. Wall splice specimens were tested under a four-point loading arrangement with the lapped bars located in the constant moment region. The applied load and specimen deflection were recorded until failure occurred. A numerical analysis was then performed to calculate the maximum resistance of the spliced bars. The specimens with contact lap splices developed the theoretical yield capacity of the reinforcing bars. In contrast, the wall splice specimens with non-contact lap splices developed an average tensile resistance of 78% of the theoretical yield capacity. The difference between the average tensile resistances of the lapped bars in the two splice arrangements was identified as being statistically significant at the 95% confidence level. On average, the contact and non-contact lap spliced bars in the double pullout specimens developed 8.47% and 41.2% less tensile resistance, respectively, as compared to the wall splice specimens with the identical splice arrangement. Both differences were identified as being statistically significant at the 95% confidence level. Bond loss between the reinforcing bars and the surrounding grout was identified as the failure mode for both the double pullout and wall splice specimens with contact lap splices. In contrast, bond loss at the masonry block/grout interface was observed along the non-contact lapped bars in both specimen types, as identified by visual observations upon removal of the face shell and the surrounding grout. Based on the test results of the wall splice specimens with non-contact lap splices, a correction factor of 1.5 is suggested when calculating the effective splice length for the non-contact splice arrangement as tested.

Purpose of this study is to use adjustable platform for development of fiber diameter and fiber fusion from 125£gm to 50£gm,125£gm to 40£gm different taper single-mode fiber, the use of different process parameters in the design of fire taper models and parameters with the molten zone, the minimum loss of 0.77dB.After the large diameter quartz capillary tube inserted into some optical fiber taper changes made after the n¡Ñ1 optical combiner, and adjusted through the design taper model parameters reduce the firepower some fiber transmission loss. In recent years, the application of high-power fiber laser in various industries is widely spreading and exploring. Within the system, one of critical component is the fiber pump combiner. We are currently investigating the fabrication of 7x1 Combiner with both single mode and multimode fibers and the characterization of combiner efficiency as a function of processing. The development of 7¡Ñ1 single-mode fiber combiner loss of about 1.5dB and 7 ¡Ñ 1 multimode fiber combiner loss of about 1.4dB

The connection between the devices of optical fiber system is an important part of optical communication equipment. For reducing the power loss in single transfer process, we couple the light from one device to another by connecting with splicer and connector. In the optical fiber communication system, the fiber must be coupled with light source or detectors and optical amplifier. The way connect fiber by fusion splice is different from the mechanical connectors, which is small joint volume, higher mechanical strength and much stable after connecting. It is more suitable to apply on micro-package optical communication device. In the study, we confer with the temperature profile and thermal stress of fusion splice module during splicing Cr4+¡GYAG crystal fiber and single mode fiber by numerical simulations. Through adjusting the parameters, like fusion current, fusion place and the processes of splice to examine the trend of change of temperature and thermal stress.

A steel frame structure of a few storey building is considered in European project FRAMEUP. Each column of the building is constructed from steel profiles connected by column-to-column connection, called column splice. In FRAMEUP project new type of column splice connection is designed to facilitate assembly. This connection consists of a plate, called finger plate with characteristic shape of holes, called long open slotted holes. A column splice with long open holes is a type of friction connection, where finger plate transfer load between bottom of one column and top of a second part and preloaded bolts are used to clamp segments together. In this work, the behaviour of the connection is investigated. Moreover, general information about column splices, friction connection and loss of pretension are introduced in literature review. A recommendations, for the preloaded bolts are investigated in accordance with European standard EN 1993-1-8. An experimental static compression tests are performed in order to observe the real behaviour of the column splice with long open slotted holes. Several number of numerical tests are performed to predict behaviour of the connection by use of Abaqus software. The Numerical model is validated against experimental results. Further tests are performed in order to check an influence of other important factors on the behaviour of connection system. An influence of connection geometry i.e. filler plate thickness, characteristic of the surface and the material properties are analyzed. The variation of bolt forces as well as slip factor and reduction factor ks are investigated. Finally, experimental test and finite element method analysis are discussed and conclusion are given. / <p>Validerat; 20140913 (global_studentproject_submitter)</p>

This thesis investigates the repair of impact-damaged prestressed concrete bridge girders with strand splices and fabric-reinforced cementitious matrix systems, specifically for repair of structural damage to the underside of an overpass bridge girder due to an overheight vehicle collision. Collision damage to bridges can range from minor to catastrophic, potentially requiring repair or replacement of a bridge girder. This thesis investigates the performance of two different types of repair methods for flexural applications: strand splice repair, which is a traditional repair method that is often utilized, and fabric-reinforced cementitious matrix repair, which is a relatively new repair method. The overarching goal of this project was to provide guidance for assessment and potential repair of impact-damaged girders. Prestressed concrete girders were tested to failure in flexure in this research. After a control test to establish a baseline for comparison, five tests were performed involving damaging a girder, repairing it using one of the repair methods, and testing it to failure. These tests showed that both strand splice repairs and fabric-reinforced cementitious matrix repairs can adequately restore the strength of an impact-damaged girder when up to 10% of the prestressing strands are severed. Combined repairs can also be a viable option if more than 10% of the prestressing strands are severed, though as the damage gets more severe, girder replacement becomes a more attractive option. / Master of Science / This thesis investigates the structural repair of impact-damaged prestressed concrete bridge girders. Impact damage to these structural elements is most commonly an overheight vehicle colliding with the underside of an overpass bridge girder on a roadway. Damage to the structure can range from minor to catastrophic. Though more destructive impacts require replacement of the girder or entire bridge structure, repair of the damaged girder is possible in some cases. This thesis studies two different methods of repair of these impact-damaged girders: strand splices and fabric-reinforced cementitious matrix. Full-scale prestressed concrete girders were tested to failure in this research. A total of five tests were performed involving damaging a girder, repairing it using one of the repair methods, and testing it to failure. These tests showed that both repair methods can adequately restore the strength of an impact-damaged girder for minor to moderate structural damage. The overarching goal of this project was to provide guidance for assessment and potential repair of impact-damaged girders.

<div>In the past decade, high-strength reinforcement (fy > 60 ksi) has become more prevalent and more widely accepted. Building codes such as ACI 318-14 do not address the use of highstrength reinforcement for proper development and splicing of reinforcement. Furthermore, research on development of high-strength reinforcement is limited. The objective of the study is to develop a suitable expression for the development and splicing of high-strength reinforcement.</div><div>Of particular interest is evaluating the influence of splice length and confinement on bond strength as well as evaluating the effectiveness of high-strength transverse reinforcement on bond strength. The study tested 22 large-scale concrete beams reinforced with ASTM A615</div><div>Grade 100 deformed steel bars: 11 specimens without transverse reinforcement within the splice region (unconfined) and 11 specimens with transverse reinforcement within the splice region (confined). Splice lengths varied from 40 bar diameters to 120 bar diameters, which are some of the largest ever tested. The effect of the test variables which were systematically studied, found</div><div>that splice strength is nonlinearly related with splice length and can be represented by a power equation. Furthermore, it was found that high-strength transverse reinforcement does not improve bond strength compared with the use of Grade 60 transverse reinforcement. Considering the test results and review of historical test results, an analytical investigation was conducted which developed a simple expression for estimating the capacity of both unconfined</div><div>and confined beams. The results are compared with the current building code design expressions as well as other proposed bond strength equations. The research conducted here provides the basis for development of a design expression that will allow for the incorporation of highstrength reinforcement in future building codes.</div>

Beam splices are typically located at moment contraflexure points (where M=0). Most design specifications require these splices to develop a strength either to meet design forces or a minimum value set by specifications. The design forces are typically determined through elastic analysis, which does not include flexibility of splice connections. In this research, two types of splice connections, an extended end plate splice connection and a flange and web plate bolted splice connection, were tested and analyzed to investigate the effect of the partial strength splice connections on structural response. The splices were designed to resist 40% and 34% of connecting section capacities using current steel design codes, respectively. It has been observed from the experiments and FEM analysis results that splice connections designed under capacities of connecting steel members can result in changes in design moment diagrams obtained from analyses without splice connection simulation and can also significantly decrease the rigidity of the structure endangering serviceability. The differences in design moment diagrams can go up to 50 % of elastic analysis without connection flexibility. The vertical displacements can increase to 155% of values obtained from elastic analysis with no splice connection simulation. Therefore, connection flexibility becomes very important to define in analysis.

<p>Twelve large-scale reinforced concrete (RC) specimens were tested at Purdue University’s Bowen Laboratory to evaluate the deformability of structural walls with longitudinal lap splices at their bases. Eight specimens were tested under four-point bending and four specimens were tested as cantilevers under constant axial force and cyclic reversals of lateral displacement. All specimens failed abruptly by disintegration of the lap splice, irrespective of what loading method was used or what splice details were chosen. Previous work on lap splices has focused mainly on splice strength. But, in consideration of demands requiring structural toughness (e.g. blast, earthquake, differential settlement), deformability is arguably more important than strength. </p> <p>Approximations of wall drift-strain relationships are presented in combination with estimates of splice strength and deformability to provide lower-bound drift capacity estimates for RC walls with lap splices at their bases. Deformations in slender structural walls (with aspect ratios larger than 3) are controlled by flexure. Shear deformations must be considered for walls with smaller aspect ratios. For slender walls with lap splices comparable to those tested, the observations collected suggest that drift capacities can be as low as 0.5%. That is: splices with minimum concrete cover, minimum transverse reinforcement (0.25% transverse reinforcement ratio) terminating in hooks, and lap splice lengths selected to reach yielding in the spliced bars (approximately 60 bar diameters for splices of Grade-60 reinforcement) can fail as yield is reached or soon after. For splices of the same length, doubling the amount of hooked transverse reinforcement increases deformation capacity by nearly 50%. By maintaining the same transverse reinforcement ratio but confining splices with closed hoops (instead of hooks), deformation capacity nearly doubles. Increasing splice length increases the expected splice strength but also increases the strain required to reach the same drift ratio. </p> <p>Evidence from this and similar experimental programs suggests that lap splices with minimum cover and confined only by minimum transverse reinforcement terminating in hooks should not be used in critical sections of structural walls when toughness is required. To prevent abrupt failure during events that demand structural toughness, it is recommended that lap splices be shifted away from locations where yielding in structural walls is expected.</p>