Management of postpartum haemorrhage reduction by the effective practices in the scope of midwife: a review

Increasing interest in the quality of healthcare has led to the focus of the maternal mortality and morbidity rate reduction. Maternal death is the death of a woman while pregnant or within 42 days of termination of pregnancy. This death could be from any cause related to pregnancy or its management. The primary Postpartum Haemorrhage (PPH) has occupied the highest factor leading to maternal mortality. PPH is the bleeding from the genital tract of 500 ml or more in the first 24 hours following the delivery of the baby. It is also significant to highlight that international medical studies have found that 69% of maternal deaths are avoidable. There is growing agreement among public health professionals that midwifery has an important contribution to provide high-quality maternal and new-born infant care. Poor quality leads to acute and chronic clinical and psychological morbidity. Therefore, new knowledge is needed to eliminate avoidable maternal and new-born mortality and morbidity. Consequently the objective of this study is to provide a review of the PPH causes and investigate and identify the role of skilled midwife in the PPH reduction. Specifically to identify extent level of breast feeding, skin to skin contact and active management of the third stage of labour on PPH. The contents of this paper provide ready-to-refer and ready-to-use information for the researchers working in the field PPH and midwife related practices

Comparison of direct shear and triaxial tests for measurement of shear strength of sand

1991 Spring.Includes bibliographic references (pages 103-104).To ascertain the shear strength parameters of soils for engineering purposes is fundamental to soil mechanics and basic for designing earth-bearing and earth-retaining structures. Direct shear and triaxial tests are the most popular laboratory methods to determine these parameters. The direct shear test is used widely because it is simple and quick. The test has several disadvantages, however. The non-uniform stress-strain behavior, the rotation of principal planes during the test, and the imposition of the failure plane are chief among them. The triaxial test was designed as a possible alternative that eliminates some of these disadvantages. Direct shear test results are always comparable to those of the triaxial test; the difference usually is negligible from a practical point of view. Researchers have tried to unfold the intricacies involved in the direct shear test especially the complicated stress-strain behavior that a soil experiences during this test. Data, however, are lacking that determine the difference and establish a correlation between the results of the two tests. This study compares the two tests for measurement of shear strength parameters of sand. Triaxial and direct shear tests were performed on silica sand under the same density and normal stress conditions. Five sets of triaxial tests and 20 direct shear tests each were performed using four different makes of direct shear machines. The results of the direct shear tests were compared with those of the triaxial tests considering the latter as benchmarks. The possible effect of the structural features of the direct shear equipment on results was briefly studied. The results showed that the shear strengths from direct shear tests are higher than those from the triaxial tests. All four direct shear machines gave cohesion values different from each other and higher than the benchmark value. The Soiltest and Wykeham Farrance machines gave almost the same friction angle that was higher than the benchmark value by 4 degrees. The friction angle value from the ELE machine was higher by 2.7 degrees while those from Clockhouse machine were lower by 4.5 degrees as compared to the benchmark value

Review of Multiaxial Testing for Very High Cycle Fatigue: From ‘Conventional’ To Ultrasonic Machines

Fatigue is one of the main causes for in service failure of mechanical components and structures. With the development of new materials, such as high strength aluminium or titanium alloys with different microstructures from steels, materials no longer have a fatigue limit in the classical sense, where it was accepted that they would have ‘infinite life’ from 10 million (107) cycles. The emergence of new materials used in critical mechanical parts, including parts obtained from metal additive manufacturing (AM), the need for weight reduction and the ambition to travel greater distances in shorter periods of time, have brought many challenges to design engineers, since they demand predictability of material properties and that they are readily available. Most fatigue testing today still uses uniaxial loads. However, it is generally recognised that multiaxial stresses occur in many full-scale structures, being rare the occurrence of pure uniaxial stress states. By combining both Ultrasonic Fatigue Testing with multiaxial testing through Single-Input-Multiple-Output Modal Analysis, the high costs of both equipment and time to conduct experiments have seen a massive improvement. It is nowadays possible to test materials under multiaxial loading conditions and for very high number of cycles in a fraction of the time compared to non-ultrasonic fatigue testing methods (days compared to months or years). This work presents the current status of ultrasonic fatigue testing machines working at a frequency of 20 kHz to date, with emphasis on multiaxial fatigue and very high cycle fatigue. Special attention will be put into the performance of multiaxial fatigue tests of classical cylindrical specimens under tension/torsion and flat cruciform specimens under in-plane bi-axial testing using low cost piezoelectric transducers. Together with the description of the testing machines and associated instrumentation, some experimental results of fatigue tests are presented in order to demonstrate how ultrasonic fatigue testing can be used to determine the behaviour of a steel alloy from a railway wheel at very high cycle fatigue regime when subjected to multiaxial tension/torsion loadings

Synthesis of Specimen Preparation and Curing Processes for Cold Recycled Asphalt Mixes

The process of cold recycling (CR) is becoming method of choice for pavement rehabilitation due to significantly added environmental and economic benefits. Understanding and standardization of specimen preparation and curing processes are critical to replicate field conditions in lab. This paper presents an extensive synthesis of various specimen preparation and curing processes for cold recycled asphalt mixes. Topics synthesized include RAP, emulsion/bitumen and aggregate preparation, mixing processes, pre- and post- compaction curing, compaction and mechanical testing. This paper was developed through efforts of cold recycling task group (TG6) of RILEM Technical Committee on Testing and Characterization of Sustainable Innovative Bituminous Materials and Systems (TC-SIB)

Ultrasonic vibration-assisted ball burnishing tool for a lathe characterized by acoustic emission and vibratory measurements

Article number 5746This paper focuses on a resonant system used to induce a low-amplitude movement and ultrasonic frequency to complement a ball burnishing process on a lathe. The system was characterized through the combination of different techniques. A full vibratory characterization of this process was undertaken with the purpose of demonstrating that the mechanical system—composed of the tool and the machine—does not present resonance phenomena during the execution of the operation that could lead to eventual failure. This dynamic analysis validates the adequateness of the tool when attached to an NC lathe, which is important to guarantee its future implementation in actual manufacturing contexts. A further aim was to confirm that the system succeeds in transmitting an oscillating signal throughout the material lattice. To this end, different static and dynamic techniques that measure different vibration ranges—including impact tests, acoustic emission measurement, and vibration measurement—were combined. An operational deflection shape model was also constructed. Results demonstrate that the only high frequency appearing in the process originated in the tool. The process was not affected by the presence of vibration assistance, nor by the burnishing preload or feed levels. Furthermore, the frequency of the assisting ultrasonic vibration was characterized and no signal due to possible damage in the material of the specimens was detected. These results demonstrate the suitability of the new tool in the vibration-assisted ball burnishing process.Feder (UE) 001-P-001822Ministerio de Ciencia, Innovación y Universidades (España) RTI2018-101653-B-I0

The effects of confining pressure on the post-yield deformation characteristics of rocks

PhD ThesisA research program into the dilatancy of Coal Measures and Coal Measures type rocks, deformed beyond the elastic rangep both up to, at and beyond the point of rupture, is outlined. Detailed descriptions of a 500 ton servo-controlled testing machine, and an apparatus for the laboratory measurement of volumetric strains in rock are given. The results of triaxial, compressive tests, conducted on specimens of seven rock types, compressed axially to strains in excess of ten percent, using this equipment, are presented. A review of the critical state model for soils is given, and a similar model for rocks is proposed, based on the experimental results obtained. The application of the measured volumetric changes of the rocks to the prediction of roadway closure, using yield zone analysis, is considered and the limitations of such analyses when considering stratified deposits discussed in conjunction with several case studies.The National Coal Board and Science Research Council

The effect of the static compaction on the mechanical and physical properties of asphalt concrete hot-mixes

The objective of this investigation was to study the effect of the static compaction effort upon the physical and mechanical properties of asphalt concrete hot mixes. To study the effect of the static compaction upon the physical properties of the asphalt mixes, six mixes were prepared using hard, well graded crushed limestone as an aggregate, blended with an 85-100 penetration grade asphalt cement. The control mix was prepared and tested in accordance with the Marshall method for mix design. The other five mixes were prepared and tested using the same procedures of Marshall except for compaction, where five different static pressures were applied. The effect of the static compaction upon the mechanical properties of the mixes was also studied. Test specimens 2.1 inches in diameter and 4.00 inches in height were compacted using different static compaction efforts. These specimens were tested in unconfined compression. Both of these studies indicated that a relationship exists between the static compaction effort and the physical and mechanical properties of the asphalt concrete mixes --Abstract, page ii

Characterization of physical and mechanical properties of rocks from Otanmäki, Finland

Abstract. Physical and mechanical properties of rocks are important parameters for geological engineering and design of engineering structures, be it in the civil and/or mining sector. Rock physical properties include density, porosity, etc., and Young’s modulus, Poisson’s ratio and rock strength include some mechanical properties of rocks. These properties can be obtained by laboratory tests. This study aims at characterizing selected rock physical and mechanical properties to assist in predicting rock mass behavior when used in engineering structures, to discuss key rock petrographical features that affect strength and compare the prediction capacities of multiple linear regression and artificial neural network (ANN) models. The study investigates selected physical and mechanical properties from two igneous rock types, gabbro and granite, from the Otanmäki area, central Finland. The test results were used for the ANN and multiple regression models. In the analyses, a total of 25 cases from the two rocks were tested for uniaxial compression strength (UCS), Young’s modulus, Poisson’s ratio, Brazilian tensile strength (BTS), density, porosity and water content. Samples were also analyzed for petrographic and chemical compositions. Results from the analyses indicate the importance of adhering to testing standards because of inconsistencies and wide variations observed between nonstandardized as opposed to standardized specimens, and the need for large database for reliable predictive models. It presents ANN techniques as having a good generalization capacity for multi-variable nonlinear prediction

Liquefaction and ring shear device

Liquefaction flow slides triggered by earthquakes or heavy rainfall in saturated granular soils have produced great damage in landslide-prone areas worldwide. A major aspect that needs more study is how the \u27residual strength\u27 remaining in the liquefied material evolves at the high strain levels imposed as the slide progresses. Strength of liquefied granular soils is usually studied in the lab by means of the triaxial test, since the strains required to trigger liquefaction are low, compared with those observed after it has been produced. More sophisticated devices are necessary in order to apply the high strains and shear strain rates that could replicate those of typical flowslides: In particular, these are required to investigate the behavior of the resistance of the flow, which is termed residual undrained strength (Sur). Preliminary tests by de Alba and Ballestero (2004) with a modified version of the triaxial cell suggested that the residual strength was not a constant number, but depended on the velocity at which the liquefied soil was being sheared (i.e., the shear strain rate). However, in order to be able to control the strains and the shear strain rates, a more sophisticated machine is necessary: the ring shear device (RSD). The RSD is designed to apply a horizontal shearing stress (cyclic or monotonic) to a ring-shaped granular soil sample. This permits the application of very large total strains and controlled strain rates to the specimen. An RSD was designed and built at the University of New Hampshire with National Science Foundation support. A testing program using the current version of the RSD was carried out using a fine uniform sand, Holliston sand . Results suggest that the residual strength is rate-dependent and that the data can be interpreted using the Herschel-Bulkley model. This model implies that shearing resistance increases with strain rate, but that the increase diminishes in an exponential fashion (i.e. flattens out) at high strain rates. Finally, data were compared with results from other RSD\u27s and with data obtained from liquefaction case histories Seed and Harder (1990); the latter provided a reasonable match with residual strengths from this study

Review of Multiaxial Testing for Very High Cycle Fatigue: From ‘Conventional’ to Ultrasonic Machines

© 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).Fatigue is one of the main causes for in service failure of mechanical components and structures. With the development of new materials, such as high strength aluminium or titanium alloys with different microstructures from steels, materials no longer have a fatigue limit in the classical sense, where it was accepted that they would have ‘infinite life’ from 10 million (107) cycles. The emergence of new materials used in critical mechanical parts, including parts obtained from metal additive manufacturing (AM), the need for weight reduction and the ambition to travel greater distances in shorter periods of time, have brought many challenges to design engineers, since they demand predictability of material properties and that they are readily available. Most fatigue testing today still uses uniaxial loads. However, it is generally recognised that multiaxial stresses occur in many full-scale structures, being rare the occurrence of pure uniaxial stress states. By combining both Ultrasonic Fatigue Testing with multiaxial testing through Single-Input-Multiple-Output Modal Analysis, the high costs of both equipment and time to conduct experiments have seen a massive improvement. It is presently possible to test materials under multiaxial loading conditions and for a very high number of cycles in a fraction of the time compared to non-ultrasonic fatigue testing methods (days compared to months or years). This work presents the current status of ultrasonic fatigue testing machines working at a frequency of 20 kHz to date, with emphasis on multiaxial fatigue and very high cycle fatigue. Special attention will be put into the performance of multiaxial fatigue tests of classical cylindrical specimens under tension/torsion and flat cruciform specimens under in-plane bi-axial testing using low cost piezoelectric transducers. Together with the description of the testing machines and associated instrumentation, some experimental results of fatigue tests are presented in order to demonstrate how ultrasonic fatigue testing can be used to determine the behaviour of a steel alloy from a railway wheel at very high cycle fatigue regime when subjected to multiaxial tension/torsion loadings.Peer reviewedFinal Published versio