Internal Strengthening Research Articles

Study on surface characteristics of 7050-T7451 aluminum alloy by ultrasonic surface rolling process

Ultrasonic surface rolling process (USRP) is an effective method to improve material surface quality, such as surface finish, microstructure, and stress state. Previously, USRP is usually used in comparably hard materials (e.g., instance steel and titanium alloys). In this paper, attention is focused on low hardness aluminum alloy which is widely used in the aviation industry. Aluminum alloy 7050-T7451 is used to investigate its surface characteristics in the ultrasonic rolling experiment. With the aid of surface optical profiler, X-ray stress analyzer, scanning electronic microscope (SEM), and energy-dispersive spectrometer (EDS), the differences of surface characteristics are explored in the USRP-treated area and that of the turning area. In addition, the influence of feed rate on surface integrity is also investigated. The results show that surface integrity is improved by USRP, and the best quality is obtained with the feed speed of 0.10 mm/r. Under the optimal experimental condition, surface roughness (Ra) is reduced to 0.059 μm, axial and tangential surface compressive residual stress is increased to −130.6 and −330.8 MPa, respectively, and surface microhardness is increased by 41.3 %. Metal flow traces, fusion of surface grain boundary, and the phenomenon of impurity phase diffusion are observed in the cross section of the treated specimen. The internal strengthening mechanism of the USRP-treated surface is probed.

Effect of Chopped Basalt Fiber on the Fresh and Hardened Properties of Fly Ash High Strength Concrete

In order to improve the mechanical properties of high strength concrete, HSC, several studies have been conducted using fly ash, FA. Researchers have made it possible to achieve 100-150MPa high strength concrete. Despite the popularity of this FAHSC, there is a major shortcoming in that it becomes more brittle, resulting in less than 0.1% tensile strain. The main objective of this work was to evaluate the fresh and hardened properties of FAHSC utilizing chopped basalt fiber stands, CBFS, as an internal strengthening addition material. This was achieved through a series of experimental works using a 20% replacement of cement by FA together with various contents of CBFS. Test results of concrete mixes in the fresh state showed no segregation, homogeneousness during the mixing period and workability ranging from 60 to 110 mm. Early and long terms of compressive strength did not show any improvement by using CBFS; in fact, it decreased. This was partially substituted by the effect of FA. Whereas, the split and flexural strengths of FASHC were significantly improved with increasing the content of CBFS as well as the percentage of the split and flexural tensile strength to the compressive strength. Also, test results showed a progressive increase in the areas under the stress-strain curves of the FAHSC strains after the CBFS addition. Therefore, the brittleness and toughness of the FAHSC were enhanced and the pattern of failure moved from brittle failure to ductile collapse using CBFS. It can be considered that the CBFS is a suitable strengthening material to produce ductile FAHSC.

Strengthening of Reinforced Concrete T-Beam with Web Opening.

This study examines shear capacity of strengthened reinforced concrete T-beams with web rectangular opening. Effect of opening orientation, presence of flange, different types of strengthening, and absence of shear reinforcement in strengthened beams are discussed and evaluated. The experimental work consisted of testing 13 beams under single point load. One of them considered as control beam without opening, while others are cast as beams with preplanned 100mm×200mm opening located at the web of the beam horizontally and vertically.
 The results of the beams indicated that the beams with horizontal openings show reduction in the ultimate shear capacity by about 17% while for vertical opening the reduction was about 27% compared to the control beam without opening .Moreover, the presence of the flange increased the shear capacity of the beams with horizontal and vertical openings by about 11% and 34.5% respectively. Also, the results indicated that the internal strengthening with inclined stirrups increased ultimate capacity by about 18% and 11% for horizontal and vertical openings compared to control T-beams with web opening respectively. The CFRP strips with spacing between them increased shear capacity by about 13.5% for horizontal opening but was not beneficial for vertical opening, also the CFRP strips for strengthening of opening made after construction were not beneficial for both types of opening and the capacity was decreased by about 11.5% and 10.1% for horizontal and vertical opening respectively. Strengthened beams with CFRP strips without spacing between them strengthened the bottom chord of the opening furthermore and they were best scheme of strengthening beam with vertical opening and increased shear capacity by about 12% for both types of opening.

The Mechanic Analysis and Construction Method on Damaged Beam of External Prestressing Reinforcement

In order to investigate the feasibility of reinforcement transformation schemes for actual engineering, Combined with the characteristics of the project, the reinforcement transformation designs of the roof beams is carried out, three kinds of reinforcement transformation design schemes are put forward, they are carbon fiber reinforced polymer strengthening, internal prestressing strengthening and external prestressing strengthening. The external prestressing reinforcement scheme is selected after comparing. Numerical simulation analysis of the reinforcement system is done by ANSYS software, and nonlinear finite element model of simply supported beam with crack is built, through analysis deformation, cracks and stress distribution of reinforced beam are obtained. The results show that the using function of beam is improved obviously. The rationality and feasibility of this reinforcement scheme is validated. These can provide references for reinforcement transformation of similar existing buildings.

La Vía Campesina: the birth and evolution of a transnational social movement

The origin and evolution of the transnational peasant movement La Vía Campesina is analysed through five evolutionary stages. In the 1980s the withdrawal of the state from rural areas simultaneously weakened corporativist and clientelist control over rural organisations, even as conditions worsened in the countryside. This gave rise to a new generation of more autonomous peasant organisations, who saw the origins of their similar problems as largely coming from beyond the national borders of weakened nation-states. A transnational social movement defending peasant life, La Vía Campesina emerged out of these autonomous organisations, first in Latin America, and then at a global scale, during the 1980s and early 1990s (phase 1). Subsequent stages saw leaders of peasant organisations take their place at the table in international debates (1992–1999, phase 2), muscling aside other actors who sought to speak on their behalf; take on a leadership role in global struggles (2000–2003, phase 3); and engage in internal strengthening (2004–2008, phase 4). More recently (late 2008–present, phase 5) the movement has taken on gender issues more squarely and defined itself more clearly in opposition to transnational corporations. Particular emphasis is given to La Vía Campesina's fight to gain legitimacy for the food sovereignty paradigm, to its internal structure, and to the ways in which the (re)construction of a shared peasant identity is a key glue that holds the struggle together despite widely different internal cultures, creating a true peasant internationalism.

Assimetria nas relações internacionais, propriedade industrial e medicamentos anti-aids

This paper analyzes the asymmetry in the international relations as refers to the recognition of industrial property rights in the pharmaceutical industry. It focuses on the impact of such relations upon the access to ARV medication, an issue of worldwide interest due to its connection with the development of the nations. Clashing interests and the position taken by some countries in their patent laws point to a scenario less favorable for the access of peripheral countries to anti-HIV/AIDS medication. On the other hand, it seems that the success of the Brazilian STD/AIDS program in negotiating ARV prices will open new possibilities. The solution may be the internal strengthening of the National States and the active role played by the Agencies of the United Nations System in defense of the collective human interests.

The study on strengthening of fluorophlogopite-based dental machinable ceramic

To study the strengthening of fluorophlogopite-based dental machinable ceramic through developing a new type of calcium-mica-based ceramic. Based on the analysis of the crystal structure of the fluorophlogopite ceramic of Dicor MGC, the structure of a new type of calcium-mica-based ceramic was designed and the corresponding composition of the new material was experimented. And the new glass-ceramic was obtained through the treatment of glass preparation and nucleation. Then crystal content of the glass ceramic was analyzed by X-ray diffraction analysis (XRD) and the 3-point bending strength of the new ceramic was recorded. A new type of calcium-mica-based glass ceramic was developed and had the 3-point bending strength of (210.2 +/- 14.7) MPa. Compared with the strength of fluorophlogopite-based dental machinable ceramic, such as Dicor MGC, which was reported in the range of 150 approximately 180 MPa within inclusive studies, the higher strength of the new ceramic was recorded. The fluorophlogopite-based dental machinable ceramic could be reinforced through internal strengthening.

Community Based Organizations in HIV/AIDS Prevention, Patient. Care and Control in Ethiopia

The main objective of this review is to provide a preliminary evaluation of the suitability of community-based organizations (CBOs) to contribute to HIV/AIDS prevention, care/support and control programs in Ethiopia. In order to put CBOs and programs in the context of HIV transmission and spread, the role of the Multisectoral HIV/AIDS Strategy (2000-2004) and other government policies and programs in promoting an environment conducive for these organizations and initiatives are highlighted. The Ethiopian literature and recent news releases on CBOs were reviewed and findings examined in the context of recent government policies, community initiatives and prevailing infrastructure in health programs, socioeconomic and cultural constraints. Findings show that the Multisectoral HIV/AIDS Strategy, the current Health Policy, and plans to strengthen the weredas and kebeles facilitate the development of CBOs and programs and infrastructure through the HIV/AIDS Council, the Ministry of Health and various other governmental organizations. CBOs studied are at different stages of planning and implementing preventive and care/support programs but little is known about their progress, operations and effectiveness due to the recency of most programs and lack of monitoring and evaluation mechanisms. Although most CBOs are either still in the formative stage or in process of carrying out HIV/AIDS prevention programs on a limited scale, their self initiative, their knowledge of and acceptance by the community and their relative cost-effectiveness render them suitable as owners, advocates and participants in programs. Several organizations and health agents are operating in integrated primary health and HIV/AIDS prevention programs that have a multi-disease, multi-organizational and poverty-reduction focus and use appropriate and promising behavioral change communication methods that may contribute significantly to overcoming social stigma and reduce HIV exposure risk. The various CBOs can be partners in HIV/AIDS prevention, patient care/support and control programs. They may facilitate efforts to curb the spread of HIV through the expansion of awareness creation and prevention initiatives and also provide patient care and support. The kebele may act as forum for community initiatives and as a link between the community and outside institutions if they can overcome bureaucratic intransigence and create an enabling environment. Towards that objective, CBOs need both internal strengthening of programs and outside support for their sustainability, and persisting stigma and discrimination against living with HIV/AIDS persons need to be reduced. Among new strategies, integrated home-based care programs involving people living with HIV/AIDS (PLWHA), families and neighbors, and poverty alleviation with an integrated HIV/AIDS component promise to create an enabling environment and promote project ownership by communities, which facilitate program design, management and effectiveness. Recommendations are made for further research towards identifying, promoting, strengthening and upscaling CBOs and programs to the regional and national levels. [Ethiopian J. Health Dev. Vol.17 Special Issue 2003: 3-31]

Upgrading the performance of steel box piers subjected to earthquakes

Bridge pier failures during earthquakes usually start with the formation of plastic hinges. In order to enhance member efficiency in the post-buckling stage, the deterioration rate must be controlled and reduced. This paper presents experimental information on the cyclic behavior of steel box piers with added internal strengthening devices. Test results show that the strength and elastic stiffness of the upgraded members stay at levels equivalent to those of the original members, however, the energy dissipation capacities of such members are substantially increased and the rates of strength deterioration are significantly reduced. Relationships between performance enhancement of members and characteristics of strengthening devices are also reported.

Performance of thin-walled box columns strengthened with internal braces

Thin-walled box members are susceptible to local buckling threat because the wall plates possess large width/thickness ratios. In order to improve the performance of the member, the deterioration of section integrity must be minimized. In this paper, the authors proposed a simple and effective method to enhance the member's performance by adding internal strengthening braces. Test results of 13 specimens show that the cyclic behavior, particularly energy dissipation, of steel thin-walled box columns with strengthening braces was significantly improved. It was also found that internal braces significantly reduced deterioration in strength after local buckling over bare steel-box section alone. The relationship between performance enhancement of members and stiffness of internal braces is also reported.

Mechanical and Thermo-Mechanical Protection by Alumina Sol-Gel Coatings

ABSTRACTAlumina coatings made by the sol-gel process using aluminum sec butox-ide can be made with variable surface area and porosity by firing on dense alumina substrates in the firing range 700 to 1000 C. These coatings are found to have large (over 100 MPa) compressive stresses and to cause a small but significant strengthening of the substrates. Within this firing range the surface area decreases while both the internal stress and strengthening effect increase with increasing firing temperature. Wear rate values are high but decrease with increasing firing temperature.

On the Use of the Term “Suture” in Entomology

Any continuous or undivided sclerotized plate of the exoskeleton is known as a sclerite and when two sclerites are contiguous the line of junction or demarcation is commonly known as a suture. Sutures in this accepted sense are of three kinds. The most common is a depressed line at the bottom of a shallow furrow or sulcus which marks the position of an internal strengthening ridge. The ridge may be formed in tnro ways.